Fatal necrotic tracheitis by Aviadenovirus in captive Alagoas curassows (Pauxi mitu) extinct from the wild

Extinct from nature, captive young Alagoas curassows (Pauxi mitu) were found agonizing or dead with respiratory disease. Intranuclear inclusion bodies were found in the epithelia of the trachea, associated with marked necrotic tracheitis. An Aviadenovirus was isolated in chicken eggs and characterized genetically with 99% identity to the fowl Aviadenovirus A, as based on the hexon protein gene. This is the first report of respiratory disease caused by Aviadenovirus in any cracid species in Brazil, recommending for stricter biosecurity in the conservation premises.

RESEARCH HIGHLIGHTS

• Fatal tracheitis in curassows extinct from nature was associated with Aviadenovirus A.

• Seven-month-old Alagoas curassows (Aves: Cracidae) died with haemorrhagic tracheitis.

• Aviadenovirus A with 99% identity to fowl adenovirus 1 was detected in dead curassows.

• Fatal tracheitis by Aviadenovirus was described in Pauxi mitu (Aves: Cracidae).

     

Pathogenicity and genomic characterization of a novel avian orthoreovius variant isolated from a vaccinated broiler flock in China

Avian orthoreovirus (ARV) infections of broiler flocks cause arthritis/tenosynovitis syndrome and significant economic losses. ARV variants were detected in the USA and Canada. Viral arthritis/tenosynovitis syndrome has occurred frequently in China in recent years. In this study, a variant ARV strain associated with viral arthritis/tenosynovitis syndrome was isolated from broilers and designated as LY383. Genomic sequence and phylogenetic analysis of the σC nucleic acid and amino acid sequences revealed that the isolate was closely related to ARV field strains Reo/PA/Layer/01224B/14, Reo/PA/Broiler/1551/13, GA/14602/2014, GA/13569/2013 and GA/13542/2013, in cluster V, but distinct from most Chinese field strains or commercial vaccine strains. Experimental challenge showed that the isolate could cause arthritis/tenosynovitis syndrome in broilers, which possessed a high level of maternal antibodies induced by commercial ARV vaccines (S1133, 1733 and T98). Furthermore, viral nucleic acid could be detected in cloacal swabs of all challenged birds throughout the entire test from 5?dpi onward. These results suggest that a novel ARV genotype emerges and might become prevalent in broiler flocks in China.

RESEARCH HIGHLIGHTS

• A variant avian orthoreovirus was isolated from a vaccinated broiler flock in North China.

• The ARV field strain was distinct from previous China-origin ARV isolates and vaccine strains.

• The current commercial ARV vaccine could not provide effective protection of broilers against the field isolate infection.

• These findings indicated that variant ARV field strains might become frequent in broiler flocks in China and effective measures should be conducted to prevent and control the disease.

     

Antigenicity,pathogenicity and immunosuppressive effect caused by a South American isolate of infectious bursal disease virus belonging to the “distinct” genetic lineage

Infectious bursal disease virus (IBDV) is the causative agent of a highly contagious immunosuppressive disease affecting young chickens. The recently described “distinct IBDV” (dIBDV) genetic lineage encompasses a group of worldwide distributed strains that share conserved genetic characteristics in both genome segments making them unique within IBDV strains. Phenotypic characterization of these strains is scarce and limited to Asiatic and European strains collected more than 15 years ago. The present study aimed to assess the complete and comprehensive phenotypic characterization of a recently collected South American dIBDV strain (1/chicken/URY/1302/16). Genetic analyses of both partial genome segments confirmed that this strain belongs to the dIBDV genetic lineage and that it is not a reassortant. Antigenic analysis with monoclonal antibodies indicated that this strain has a particular antigenic profile, similar to that obtained in a dIBDV strain from Europe (80/GA), which differs from those previously found in the traditional classic, variant and very virulent strains. Chickens infected with the South American dIBDV strain showed subclinical infections but had a marked bursal atrophy. Further analysis using Newcastle disease virus-immunized chickens, previously infected with the South American and European dIBDV strains, demonstrated their severe immunosuppressive effect. These results indicate that dIBDV strains currently circulating in South America can severely impair the immune system of chickens, consequently affecting the local poultry industry. Our study provides new insights into the characteristics and variability of this global genetic lineage and is valuable to determine whether specific control measures are required for the dIBDV lineage.

Research Highlights

• A South American strain of the dIBDV lineage was phenotypically characterized.

• The strain produced subclinical infections with a marked bursal atrophy.

• Infected chickens were severely immunosuppressed.

• The dIBDV strains are antigenically divergent from other IBDV lineages.

     

MinION sequencing to genotype US strains of infectious laryngotracheitis virus

Over the last decade the US broiler industry has fought long-lasting outbreaks of infectious laryngotracheitis (ILTV). Previously, nine genotypes (I-IX) of ILTVs have been recognized using the polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method with three viral alleles (gB, gM and UL47/gG). In this study, the genotyping system was simplified to six genotypes by amplicon sequencing and examining discriminating single nucleotide polymorphisms (SNPs) within these open reading frames. Using phylogenomic analysis of 27 full genomes of ILTV, a single allele (ORF A/ORF B) was identified containing SNPs that could differentiate ILTVs into genotypes congruent with the phylogenetic partitioning. The allelic variations allowed for the cataloging of the 27 strains into 5 genotypes: vaccinal TCO, vaccinal CEO, virulent CEO-like, virulent US and virulent US backyard flocks from 1980 to 1990, correlating with the PCR-RFLP genotypes I/ II/ III (TCO), IV (CEO), V (virulent CEO-like), VI (virulent US) and VII/VIII/IX (virulent US backyard flock isolates). With the unique capabilities of third generation sequencing, we investigated the application of Oxford Nanopore MinION technology for rapid sequencing of the amplicons generated in the single-allele assay. This technology was an improvement over Sanger-based sequencing of the single allele amplicons due to a booster amplification step in the MinION sequencing protocol. Overall, there was a 90% correlation between the genotyping results of the single-allele assay and the multi-allele assay. Surveillance of emerging ILTV strains could greatly benefit from real-time amplicon sequencing using the single-allele assay and MinION sequencing.

RESEARCH HIGHLIGHTS

• A multi-allelic assay identified nine ILTV genotypes circulating in the US

• Single-allele genotyping is congruent with whole genome phylogenetic partitioning

• US ILTV strains can be grouped into five genotypes using the single-allele assay

• The single-allele assay can be done using MinION sequencing of barcoded amplicons

     

Anatomopathological changes,quantification and distribution of Libyostrongylus spp. in regions of the proventriculus and ventriculus of naturally- and experimentally-infected ostriches

Nematodes of the genus Libyostrongylus parasitize ostriches, causing high mortality rates. These nematodes are found in the proventriculus and ventriculus of ostriches, but little is known about their distribution and the possible anatomopathological changes they cause in the various regions of these organs. This paper describes the distribution and quantification of Libyostrongylus and pathological changes found in regions of the proventriculus and ventriculus of ostriches with high and low levels of both natural and experimental infection. Ostriches were necropsied and tissue samples from the distinct regions of both organs were analysed based on nematode counts and histopathology after staining with haematoxylin and eosin, Masson’s trichrome or Alcian blue/PAS. The cranial and glandular regions of the proventriculus were the most parasitized. The ventriculus contained more nematodes in the caudal region. No macro- or microscopic pathological changes were observed in either of these organs of experimentally-infected birds. However, naturally-infected birds with high levels of infection presented proventriculus with macroscopic lesions and heterophilic infiltrates surrounding nematodes. In the glandular region of this organ, nematodes were located in the adenomeres of the secretory ducts, causing altered architecture and erosions and ulcerative lesions with damaged epithelium. Nematode eggs were found in the koilin layer of the middle and caudal regions of the ventriculus only of these birds. The pH of the regions assessed by Alcian blue/PAS staining changed from acidic in the proventriculus to more alkaline in the caudal region of the ventriculus. These data add knowledge to the biology of Libyostrongylus.

RESEARCH HIGHLIGHTS

• The most parasitized areas were the cranial and glandular regions of the proventriculus.

• Naturally-infected birds with high levels of infection presented macro lesions in the proventriculus and damaged epithelium.

• Nematode eggs were found in the ventriculus.

• The proventriculus had an acidic pH, which turned alkaline towards the ventriculus.

     

Vaccination of chickens with the 34 kDa carboxy-terminus of Bpmp72 reduces colonization with Brachyspira pilosicoli following experimental infection

The anaerobic intestinal spirochaete Brachyspira pilosicoli colonizes the large intestine of a variety of species of mammals and birds, and may result in colitis, diarrhoea and reductions in growth rate. Naturally occurring infections in chickens are largely confined to adult laying and breeding birds. In this study, the 34 kD carboxy-terminus of the prominent outer membrane protein Bmp72 of B. pilosicoli was expressed as a histidine-tagged recombinant protein and used to immunize two groups (B and C) of 15 individually housed layer chickens. Vaccination was with either 100?μg (B) or 1?mg (C) protein emulsified with Freund’s incomplete adjuvant delivered into the pectoral muscles, followed three weeks later by 1?mg of protein in phosphate buffered saline delivered via crop tube. Two weeks later these and 15 non-vaccinated positive control birds (group A) housed in the same room were challenged via crop tube with B. pilosicoli avian strain CPS1. B. pilosicoli was detected in the faeces of all control birds and in 14 of the vaccinated birds in each vaccinated group at some point over the 30-day period following challenge. Colonization was delayed and the duration of excretion was significantly reduced (P?=?0.0001) in both groups of vaccinated birds compared to the non-vaccinated control birds. Fewer immunized birds had abnormal caecal contents at post mortem examination compared to non-vaccinated birds, but the difference was not statistically significant. This study indicates that recombinant Bmp72 C-terminus has potential to be developed for use as a vaccine component to provide protection against B. pilosicoli infections.

RESEARCH HIGHLIGHTS

• Laying chickens were immunized with recombinant Brachyspira pilosicoli membrane protein Bpmp72.

• Immunized birds had a highly significant reduction in the duration of colonization.

• Fewer immunized than control birds had abnormal caecal contents after infection.

• Bpmp72 showed potential for use as a novel vaccine component for B. pilosicoli.

     

Pathology of clade 2.3.2.1 avian influenza virus (H5N1) infection in quails and ducks in Bangladesh

We performed pathological and molecular virological investigation of three outbreaks of highly pathogenic avian influenza (HPAI) in a quail farm and two duck farms of Mymensingh and Netrokona districts of Bangladesh in 2011. HPAI viruses of subtype H5N1 were detected from all three outbreaks and phylogenetic analysis of HA gene sequence placed the viruses into clade 2.3.2.1. The outbreak in the quail farm was characterized by acute death with 100% mortality within two days. Marked haemorrhages and congestion with necrotic and inflammatory lesions in the respiratory tract, liver, pancreas and kidneys were the major gross and histopathological lesions. In the case of ducks, nervous signs were the remarkable clinical manifestations and the mortality was around 10%. No significant gross lesions were observed at necropsy. Non-purulent encephalitis with gliosis and neuronal degeneration was observed on histopathological examination. By immunohistochemistry, viral antigen could be detected in different organs of both quails and ducks. This study records varying clinical and pathological manifestations of HPAI in ducks and quails following natural infection with the same strain of the virus.

RESEARCH HIGHLIGHTS

• HPAIV of clade 2.3.2.1 was detected from clinical outbreaks in quails and ducks

• Sudden death with severe haemorrhages in various organs was found in quails

• Pronounced nervous signs with non-purulent encephalitis were observed in ducks

• Viral antigen could be localized in different organs by immunohistochemistry

     

Changes in gut bacterial communities in canaries infected by Macrorhabdus ornithogaster

Macrorhabdus ornithogaster is an opportunistic yeast that colonizes the gastric mucosa of many avian species. Until now, no studies have focused on the influence of a gastric infection on the balance of the intestinal microbiota of birds. In this study, 44 faecal samples from individual canaries, with and without M. ornithogaster infection, were analysed. The detection of the yeast was evaluated by 18S rRNA PCR. In order to evaluate the impact of the Macrorhabdus infection on the bacterial communities, culture-independent methods, by the use of amplicon-based sequencing as well as 16S rRNA-DGGE, were adopted. The different health status of animals affected the relative abundance of the main OTUs, with a greater diversification of the gut microbiota in healthy animals compared to the infected. In particular, Lactococcus, Pseudomonas, Acinetobacter, Lachnospiraceae, Propionibacterium and Weissella were found to be characteristic of uninfected animals (FDR?<?0.05), while Lactobacillus and Candidatus Arthromitus were characteristic of infected animals (FDR?<?0.05). Both these taxa have been reported as immunostimulatory, involved in immunological disorders. In infected animals the inferred metagenome assessed by PICRUST clearly showed a positive correlation between the presence of M. ornithogaster and KEGG genes related to ether lipid metabolism, already reported to be immunostimulatory by activation of macrophages and to play a pathophysiological role in several immunological disorders. Finally, our results show an interaction between infection of the digestive tract and intestinal microbiota of pet birds and provide insight into the changing of the complex enteric bacterial community.

• HIGHLIGHTS

• Macrorabdus ornithogaster is a gastric yeast that colonizes a wide range of birds.

• Differences were found between infected and healthy animals in gut microbiota.

• Candidatus Arthromitus was closely associated with infected birds.

• M. ornithogaster can affect intestinal microbiota composition of canaries.

     

Protection afforded by avian influenza vaccination programmes consisting of a novel RNA particle and an inactivated avian influenza vaccine against a highly pathogenic avian influenza virus challenge in layer chickens up to 18 weeks post-vaccination

The efficacies of an oil adjuvanted-inactivated reverse genetics-derived H5 avian influenza virus (AIV) vaccine and an alphavirus replicon RNA particle (RP) AIV vaccine were evaluated in commercial Leghorn chickens. Challenge utilized A/turkey/MN/12582/2015, an isolate representing the U.S. H5N2 Clade 2.3.4.4 responsible for the 2015 highly pathogenic avian influenza (HPAI) epornitic in commercial poultry the United States. As part of a long-term, 36-week study, chickens were challenged at seven weeks of age after receiving a single vaccination, at 18 weeks of age following a vaccine prime-single boost, and at 36 weeks of age after a prime- double-boost. All vaccine programmes reduced virus oropharyngeal and cloacal shedding and mortality compared to the non-vaccinated control birds; however, chickens receiving at least one administration of the RP vaccine generally had diminished viral shedding especially from the cloacal swabbings. A detectable serum antibody response and protection were observed through 18 weeks post-vaccination. Our data suggest that, in conjunction with a comprehensive eradication, enhanced biosecurity and controlled marketing plan, vaccination programmes of commercial layer chickens with novel RP vaccines may represent an important tool for preventing HPAI-related mortalities and decreasing viral load during a catastrophic influenza outbreak.

RESEARCH HIGHLIGHTS

• Immunization of poultry following a vaccination schedule consisting of inactivated and RNA particle vaccines offered significant protection against lethal disease following HPAIV challenge.

• Virus shedding was significantly (P?<?0.05) reduced in chickens vaccinated with either inactivated and/or recombinant vaccines.

• Serum antibody titres were not a reliable indicator of protection.

• An inactivated vaccine containing 384 HAU of the homologous antigen was unable to induce complete protection.

     

Dose-dependent differential resistance of inbred chicken lines to avian pathogenic Escherichia coli challenge

Avian pathogenic E. coli (APEC) cause severe respiratory and systemic disease. To address the genetic and immunological basis of resistance, inbred chicken lines were used to establish a model of differential resistance to APEC, using strain O1 of serotype O1:K1:H7. Inbred lines 7₂, 15I and C.B12 and the outbred line Novogen Brown were inoculated via the airsac with a high dose (10⁷ colony-forming units, CFU) or low dose (10⁵ CFU) of APEC O1. Clinical signs, colibacillosis lesion score and bacterial colonization of tissues after high dose challenge were significantly higher in line 15I and C.B12 birds. The majority of the 15I and C.B12 birds succumbed to the infection by 14?h post-infection, whilst none of the line 7₂ and the Novogen Brown birds developed clinical signs. No difference was observed after low dose challenge. In a repeat study, inbred lines 7₂ and 15I were inoculated with low, intermediate or high doses of APEC O1 ranging from 10⁵ to 10⁷ CFU. The colonization of lung was highest in line 15I after high dose challenge and birds developed clinical signs; however, colonization of blood and spleen, clinical signs and lesion score were not different between lines. No difference was observed after intermediate or low dose challenge. Ex vivo, the phagocytic and bactericidal activity of lung leukocytes from line 7₂ and 15I birds did not differ. Our data suggest that although differential resistance of inbred lines 7₂, 15I and C.B12 to APEC O1 challenge is apparent, it is dependent on the infectious dose.

• Research Highlights

• Lines 15I and C.B12 are more susceptible than line 7₂ to a high dose of APEC O1.

• Differential resistance is dose-dependent in lines 15I and 7₂.

• Phagocytic and bactericidal activity is similar and dose independent.

     

Physiological,biochemical and histopathological changes associated with heatstroke in the galah (Eolophus roseicapilla) and rock dove (Columba livia)

The pathophysiology of heat illnesses in birds has not been well characterized. In this study, we describe the changes in heart rate, respiratory rate, blood biochemistry and histopathological findings in galahs and rock doves after heat exposure under standardized conditions designed to induce heatstroke. Birds in the heat-exposed group were exposed to environmental heat stress and compared to control birds. Both groups of birds were under general anaesthesia throughout the experiment and serial blood collections were performed for biochemical analyses, while organs were collected at the end of the experiment for histopathology. No electromyography traces consistent with the onset of heat cramps were observed in any of the birds. Biochemical changes suggestive of skeletal muscle and hepatocellular injury, including hyperkalaemia and increased serum muscle and hepatic enzyme activities, were often observed in heat-exposed galahs and rock doves at the onset of heatstroke. Microscopic analyses did not reveal any significant cardiac changes, although some lungs had signs of acute congestion. Some heat-exposed rock doves had microscopic changes indicative of necrosis in the pectoral muscle. There were significant hepatic changes in some heat-exposed galahs, but not in rock doves. This suggests that there may be species differences amongst birds in the organs most affected by heatstroke. The observed species differences in the physiological, biochemical and histopathological changes indicate that bird species should be studied separately for clinical syndromes such as heatstroke.

RESEARCH HIGHLIGHTS

• Biochemical changes suggestive of skeletal muscle and hepatocellular injury in heat-exposed galahs and rock doves at the onset of heatstroke

• No electromyography traces consistent with the onset of heat cramps were observed

• Some heat-exposed rock doves had indications of necrosis in the pectoral muscle

• There were significant hepatic changes in some heat-exposed galahs

     

Detection of Histomonas meleagridis DNA in dust samples obtained from apparently healthy meat turkey flocks without effect on performance

Environmental dust samples obtained from 65 turkey flocks in France, of which six suffered from histomonosis whereas the rest remained apparent healthy until the end of production, were tested for the presence of Histomonas meleagridis DNA by recently developed real-time PCR based on the 18S rRNA locus. In order to determine the genotype of detected histomonads, positive samples were further subjected to conventional 18S PCR and sequencing. Additionally, production data of all tested flocks, such as average daily gain, feed conversion ratio and production index, were statistically evaluated and compared to see the effect of positive dust samples in apparently healthy flocks. Histomonad DNA was detected in the dust obtained from all six clinically affected and, surprisingly, in nine apparent healthy flocks. Sequencing of the 18S rRNA gene resulted in only one DNA sample homologous to H. meleagridis whereas 11 others revealed the presence of several other flagellates. Average daily gain and production index were negatively affected in flocks with clinical histomonosis, resulting in significant difference in comparison with the data obtained from clinically healthy flocks independent of the presence of histomonad DNA in the dust. Overall, there was no significant difference following statistical analysis of production parameters between the two last mentioned groups of tested flocks. Altogether, this is the first investigation demonstrating the presence of H. meleagridis DNA in environmental dust samples obtained from clinically unaffected turkey flocks. However, this finding could not be correlated with impact on production based on analysis and comparison of selected production data.

RESEARCH HIGHLIGHTS

• Environmental dust obtained from clinically healthy turkey flocks, in addition to dust from flocks affected by histomonosis, was found positive for the presence of Histomonas meleagridis DNA.

• Histomonas-positive dust samples in clinically unaffected flocks did not have a negative effect on production parameters.

• The results demonstrate a wider spread of H. meleagridis DNA in flocks of commercial meat turkeys than previously thought.

     

Comparison of the short-term and long-term efficacies of the Mycoplasma gallisepticum vaccines ts-11 and 6/85

In order to compare the short-term efficacies of the live attenuated Mycoplasma gallisepticum (MG) vaccine strains ts-11 and 6/85, four groups of SPF chickens were vaccinated with each of the vaccines using eye drop and aerosol inoculations, and were subsequently challenged with a wild-type MG strain. When administered by the recommended routes (eye drop for ts-11 and fine aerosol for 6/85), both vaccines induced substantial and comparable levels of protection against airsacculitis and tracheitis caused by wild-type MG. The long-term efficacies of the two vaccines administered by the recommended route were also assessed. Serum antibody responses and colonization of the vaccines in the upper respiratory system were monitored at different time points after vaccination, and protective efficacies of the vaccines were evaluated at 36 weeks post vaccination as above. Systemic antibody response following ts-11 eye drop vaccination was initially strong but reduced gradually over time while, in contrast, that to 6/85 spray vaccination was initially weak but increased over time. Kinetics of the antibody response to the vaccines appeared to be correlated with the number of birds harbouring each vaccine in their upper respiratory system throughout the sampling timepoints. Regardless of the levels of serum antibodies or number of birds harbouring the vaccine, both vaccines induced substantial and comparable levels of protection against airsacculitis and tracheitis caused by wild-type MG. Therefore, kinetics of systemic antibody response and persistence in the upper respiratory system varies between vaccine strains; however, the levels of protection may not, at least up to 36 weeks post vaccination.

RESEARCH HIGHLIGHTS

• The kinetics of systemic antibody response and persistence of the vaccine in the upper respiratory system varies between vaccine strains ts-11 and 6/85.

• The levels of protection induced by the two vaccines against virulent MG strain challenge are comparable when they are administered by the route recommended by their manufacturers.

     

Biological characteristics and immunological properties in Muscovy ducks of H5N6 virus-like particles composed of HA-TM/HA-TMH3 and M1

Highly pathogenic avian influenza viruses (HPAIVs), including H5N6 strains, pose threats to the health of humans and poultry. Waterfowl play a crucial role as a reservoir of HPAIVs. Since current influenza vaccines induce poor antibody titres in waterfowl, there is an urgent need to develop an efficient vaccine against H5N6 infection. In this study, we constructed two H5N6 virus-like particles (VLPs) composed of matrix-1 (M1) and haemagglutinin of wildtype (HA-TM) or haemagglutinin with transmembrane domain replacement (HA-TM_H3) (designated as H5N6 VLPs-TM and H5N6 VLPs-TM_H3). Biological characteristics of the composed H5N6 VLPs were compared including localization, expression, contents of HA trimers, thermal stability, morphology and immunogenicity in Muscovy ducks. Our results indicate that the H5N6 VLPs-TM_H3 contained more HA trimers and presented better thermal stability. Moreover, Muscovy ducks immunized with H5N6 VLPs-TM_H3 produced higher titres of HI antibody and IFN-γ compared with those immunized with the same dose of H5N6 VLP-TM, thus providing a promising approach for the development of influenza virus vaccines for waterfowl.

RESEARCH HIGHLIGHTS

• H5N6 VLPs-TM_H3 had more HA trimers and resisted higher temperature than H5N6 VLPs-TM

• H5N6 VLPs-TM_H3 induced higher titre of HI than H5N6 VLPs-TM in Muscovy ducks

     

Comparative pathogenicity of two subtypes (hepatitis-type and pancreatitis-type) of duck hepatitis A virus type 1 in experimentally infected Muscovy ducklings

Duck hepatitis A virus type 1 (DHAV-1) causes acute hepatitis with high morbidity and mortality in ducklings of the genera Cairina and Anas and is characterized by ecchymotic haemorrhage and necrosis of the liver surface. Since September 2011, a new subtype of DHAV-1 (named pancreatitis-type DHAV-1) has been isolated. This new subtype is characterized by yellowish or haemorrhagic pancreatitis, but with no significant pathological changes in the liver. To further investigate the difference in pathogenicity between hepatitis-type DHAV-1 and pancreatitis-type DHAV-1, we infected Muscovy ducklings with a hepatitis-type DHAV-1 strain, FZ86, or a pancreatitis-type DHAV-1 strain, MPZJ1206, and then compared the resulting gross lesions, histopathological changes, viral distribution and cellular apoptosis in the liver and pancreas of Muscovy ducklings. The results suggested that FZ86 induced a more efficient viral propagation in the liver than MPZJ1206, and the gross and histopathological lesions were also limited to the liver. However, MPZJ1206 induced more effective viral replication in the pancreas than FZ86. The MPZJ1206-infected Muscovy ducklings showed an obviously yellowed and haemorrhagic pancreas, but with no significant pathological changes in the liver. Furthermore, FZ86 induced notable hepatocyte apoptosis and increased the expression of caspase-3 in the liver, whereas MPZJ1206 caused apoptosis in a large number of acinar epithelial cells and elevated the expression of caspase-3 in the pancreas. Taken together, these results demonstrated that pancreatitis-type DHAV-1 has many new pathogenic features which distinguish it from the hepatitis-type DHAV-1.

RESEARCH HIGHLIGHTS

• Pancreatitis-type DHAV-1 (MPZJ1206) was characterized by pancreatic haemorrhage and yellow discolouration, but with no obvious haemorrhage and necrosis in the liver.

• Pancreatitis-type DHAV-1 (MPZJ1206) exhibits many new pathogenic features which distinguish it from the hepatitis-type DHAV-1 (FZ86).

     

Phenotypic characteristics of Riemerella anatipestifer and similar micro‐organisms from various hosts

A total of 199 Riemerella anatipestifer (RA) and RA‐like field strains isolated culturally from birds of 12 different species and from pigs were characterized using classical phenotypic and chemotaxonomic tests. The RA reference strain ATCC 11845 was included in the study.

On the basis of the classical phenotypic characteristics studied and the numerical analysis of the whole‐cell fatty acid patterns, the RA reference strain and 123 field isolates were assigned to the indole negative (IN) variant and 10 isolates to the indole positive (IP) variant of the species RA. The IN strains were isolated not only from poultry and free‐living wild ducks, but also from pigs, guillemots and from a budgerigar and a herring gull. All the IP isolates were isolated from domestic ducks. One field strain from a chicken and one from a black‐headed gull, which were distinguished from RA mainly by the negative a‐glucosidase reaction and production of yellow pigment respectively, showed fatty acid methyl ester profiles chemotaxometrically different from those of RA.

Another 64 field strains isolated from domesticated ducks, geese and muscovy ducks with signs and lesions very similar to those caused by RA were phenotypically and chemotaxometrically clearly different from RA and could not be classified to any of the known species. This possible bacterial pathogen is therefore given the preliminary designation of Riemerella‐like (RA‐L) taxon 1502.     

UBASH3A gene polymorphisms and expression profile in rheumatoid arthritis

Objectives: Recent evidence has demonstrated that UBASH3A play a pivotal role in multiple autoimmune diseases. In this study, we explored the association between UBASH3A gene single-nucleotide polymorphisms (SNPs) and rheumatoid arthritis (RA) in a Chinese Han population. We also comparatively evaluated the UBASH3A expression profile in peripheral blood mononuclear cells (PBMCs) from patients with RA and healthy controls.

Methods: Four UBASH3A polymorphisms (rs1893592, rs11203203, rs2277798, and rs3788013) were studied in 553 patients with RA and 587 controls in a Chinese population. Genotyping was performed using the Fluidigm 192.24 Dynamic Array Integrated Fluidic Circuit (IFC). For gene expression study, UBASH3A mRNA levels of 30 RA patients and 31 healthy individuals were assessed by real-time quantitative polymerase chain reaction (RT-qPCR). Data were analyzed by SPSS 19.0 software.

Results: A significant association between rs1893592 polymorphism and RA was found under all genetic models (all p<.05). We also discovered a significant association between rs3788013 polymorphism and RA in the allele and genotype distributions, as well as the recessive model (all p<.05). Moreover, we found the genotype distribution and allele frequency of rs1893592 were significantly associated with RF phenotype in the RA patients (χ²?=?6.786, p=.034; χ²?=?4.534, p=.033; respectively). We also found the genotype distribution and allele frequency of rs2277798 were significantly associated with anti-CCP phenotype in the RA patients (χ²?=?7.873, p=.020; χ²?=?4.473, p=.034; respectively). However, we did not detect any significant associations between rs11203203 and RA susceptibility and autoantibody profiles (all p>.05). The mRNA expression of UBASH3A was increased in PBMCs of patients with RA when compared to healthy controls (p=.001).

Conclusions: Our observations suggested that the dysregulation of UBASH3A might be associated with the pathogenesis of RA, and UBASH3A gene polymorphisms (rs1893592 and rs3788013) might contribute to RA susceptibility in Chinese Han population.     

How can Dermanyssus gallinae (De Geer 1778) (Acari: Anactinotrichida: Dermanyssidae) walk upwards on slippery surfaces?

ABSTRACT

Scanning electron microscopy observations of the distal leg region of the poultry red mite Dermanyssus gallinae (De Geer 1778) identified the presence of a compound ambulacrum, the part of the leg that contacts the substratum when the mite walks. The ambulacrum is comprised of a praetarsus (the ambulacrum stalk), a pulvillus and two claws. The pulvillus is a weakly sclerotized structure that can be partly expanded or retracted in the praetarsus. When expanded, the pulvillus shows a cushion-like shape which can, as a result of its soft surface, function as a sucker, thus allowing D. gallinae to adhere to a smooth surface. When traversing an irregular surface, or clinging to a soft surface, the mite retracts the pulvillus and uses only its strongly sclerotized movable claws. These observed morphological adaptations explain the ability of D. gallinae to climb upwards on a slippery surface, resist an air flux, walk on smooth and rigid feathers of its avian hosts, and cling to the bird’s or human's soft skin. This knowledge is important to better understand the attachment mechanism of this species to its host and to the substratum on which it moves, and also to provide insight into the circumstances under which it is able to move.

RESEARCH HIGHLIGHTS

• The ambulacrum is the distal part of the leg touching the substratum

• D. gallinae’s ambulacrum consists of a praetarsus, a pulvillus and two claws

• The weakly sclerotized pulvillus can be part expanded/retracted in the praetarsus

• The expanded pulvillus functions as a sucker to adhere to smooth surfaces

• The claws are used to walk on an irregular surface or cling to a soft surface

     

Cross-species transmission of poultry pathogens in backyard farms: ducks as carriers of chicken viruses

ABSTRACT

In backyard farms of Lao People’s Democratic Republic, mixed-species rearing of poultry is a breeding-ground for cross-species transmission. Here, the epidemiology of viruses circulating among backyard poultry in Vientiane Province was assessed to guide future control strategies. Oral/tracheal and cloacal swabs, collected from 605 poultry (308 ducks, 297 chickens) between 2011 and 2015, were screened by PCR for Newcastle disease virus (NDV), coronavirus (CoV) and chicken anaemia virus (CAV). Chicken sera were screened for anti-NDV antibodies by ELISA. Statistical and phylogenetic analyses revealed transmission patterns and relationships.

Closely related strains co-circulated in chickens and ducks. While CoV RNA was detected in oral/tracheal swabs of 9.3% of the chickens and 2.4% of the ducks, rates were higher in faecal swabs of both species (27.3% and 48.2%). RNA of infectious bronchitis virus (IBV) and duck CoV was found in faecal swabs of chickens (19.7% and 7.1%) and ducks (4.1% and 44.1%). Moreover, DNA of the generally chicken-specific CAV was detected in oral/tracheal swabs of chickens (18.1%) and, sporadically, of ducks (2.4%). Despite serological evidence of NDV circulation or vaccination (86.9%), NDV RNA was not detected. We found a high prevalence and indication for cross-species transmission of different CoV strains in backyard poultry. Interestingly, ducks served as biological, or at least mechanical, carriers of viral strains closely related not only to IBV, but also to CAV. Bird containment and poultry species separation could be first steps to avoid cross-species transmission and emergence of novel strains with broad host range and enhanced pathogenicity.

RESEARCH HIGHLIGHTS

• High rates of avian viruses were detected by PCR in backyard poultry from Lao PDR.

• Diverse coronavirus and chicken anemia virus strains co-circulated.

• Phylogenetic analyses suggested virus transmission between chickens and ducks.

• Serological evidence of Newcastle disease was found, but viral RNA was not detected.

     

Dermanysuss gallinae attacks humans. Mind the gap!

ABSTRACT

Dermanyssus gallinae is a haematophagous ectoparasite primarily known as a pest of domestic and wild birds. It occasionally feeds on a range of mammals, and, more importantly, is of growing concern in human medicine. This review highlights mite attacks on people working with poultry, and updates the increasing incidence of dermanyssosis in urban environments in Europe. Although several cases of dermanyssosis have been documented, there are a number of reasons why diagnosis of D. gallinae infestations in humans is likely to be underestimated. Firstly, medical specialists are not well aware of D. gallinae infestations in humans. There is also a lack of collaboration with specialists from other disciplines. The problem is compounded by misdiagnoses and by the lack of diagnostic tools. We review the literature on human dermanyssosis cases in Europe, and also provide information on the epidemiology, clinical, histo-pathological and immunological aspects of dermanyssosis. We stress the need for improved recognition of this challenging infestation in humans, and provide straightforward recommendations for health practitioners, starting with collection of the correct anamnestic information and including appropriate management methods for case recognition and resolution. Finally, we indicate the most urgent areas to be addressed by future research.

RESEARCH HIGHLIGHTS

• Dermanyssus gallinae is of growing concern in human medicine.

• Most physicians are not well aware of dermanyssosis in humans.

• Bio-epidemiological and clinical aspects of this ectoparasitosis are highlighted.

• Practical key actions for diagnosis and correct management of infestation in humans are provided.