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

     

New PA/1220/98-like variant of infectious bronchitis virus in Poland

ABSTRACT

The aim of the present study was to report the first detection of a new infectious bronchitis virus (IBV) variant in Polish commercial flocks which is completely different to any previously known in this region. In 2018, samples from Ross 308 breeding hens aged 35 weeks were delivered for IBV diagnosis. IBV presence was detected, but all attempts to amplify the S gene fragment were negative. The field material was analysed using the Illumina MiSeq platform and a 1073-nt fragment of the S1 coding region was obtained. The gCoV/ck/Poland/516/2018 strain shared only 52.7–58.1% nucleotide identity to any known genotype of IBV and shared the highest identity of 81.4% to the unique North American PA/1220/98 variant. Based on the obtained sequence, a specific molecular test was constructed and used for screening of chicken samples from 35 field cases delivered to our laboratory between 2018 and 2019 for IBV diagnosis. Application of this test enabled detection of another three chicken flocks as positive for this new strain. All positives were identified in commercial layers with egg production problems. To date, the virus has not been detected in broiler chickens. Taking into account the proposed criteria for the definition of a new IBV genotype or lineage, it seems that the detected viruses in Poland, together with the unique North American PA/1220/98 variant, may be classified as separate lineages/genotype in the new IBV classification.

RESEARCH HIGHLIGHTS

• The new IBV variant is distantly related to other known GI–GVII IBV genotypes/lineages.

• It affects long-lived birds causing egg production problems.

• The detected IBV and the unique North American PA/1220/98 variant are candidates for separate lineages in the new GVIII genotype.

     

Genotyping of Riemerella anatipestifer by ERIC-PCR and correlation with serotypes

Riemerella anatipestifer (RA) is a widely distributed bacterial pathogen of birds responsible for remarkable losses to poultry production, especially among waterfowl. We characterized the genomic diversity of 166 field isolates of RA, collected from geese and ducks, using enterobacterial repetitive intergenic consensus (ERIC)-polymerase chain reaction (PCR). The field strains and five reference strains showed 17 distinct patterns consisting of five to 12 bands ranging from approximately 150–1800bp. The majority of the strains belonged to two closely related ERIC-PCR types (A and B), while the other types contained only a few isolates each. There was no association between ERIC-PCR type and host species, place, or year of isolation; however the ERIC-PCR pattern was correlated with serotype for most isolates. The majority of serotype 1 strains (101/107) belonged to ERIC-PCR type A while the remaining six strains represented five different ERIC-PCR types (D, G, L, M, and O). Serotypes 1,7 and 7 corresponded to ERIC-PCR types B and C, respectively. Serotypes 2, 4, and 10 could be subdivided by ERIC-PCR revealing two to four patterns within each serotype. These results indicate that ERIC-PCR may be a suitable technique for the molecular identification of RA serotypes, and the detection of subtypes within certain serotypes may aid further epidemiological investigations.

RESEARCH HIGHLIGHTS

• ERIC-PCR analysis of field R. anatipestifer strains revealed 17 distinct patterns

• Most strains belonged to two closely related ERIC-PCR types

• Serotype 1 was the most prevalent serotype representing 64.5% of the strains

• ERIC-PCR may be suitable for molecular identification of R. anatipestifer serotypes

     

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.

     

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.

     

Molecular characterization of avian reovirus causing tenosynovitis outbreaks in broiler flocks,Iran

ABSTRACT

Avian reoviruses (ARVs) cause arthritis, tenosynovitis, retarded growth, and malabsorption syndrome. After a long time of effective prevention and low rates of viral arthritis/ tenosynovitis in Iran, outbreaks of tenosynovitis in broiler flocks have increased in recent years. Lameness, splay legs, high rate of cull birds, poor performance, uneven birds at harvest, and condemnation at processing cause huge economic losses. In this study, ARVs from the tendons of birds from 23 broiler flocks with marked tenosynovitis were characterized, and their genetic relationship was examined. Analysis of the amino acid sequence of Sigma C protein revealed that all ARVs detected in affected broiler flocks shared genetic homogeneity and this suggests that a single genotype is involved in recent outbreaks. This genotype, so-called “Ardehal strain”, is grouped in cluster I with vaccine strains. The amino acid sequence similarity between Ardehal and vaccine strains, including S1133, 1733, and 2408 was less than 80%. As the outbreaks have occurred in progenies of vaccinated flocks, it is proposed here that the difference between vaccine and field strains might contribute to the failure of currently available vaccines to induce protective immunity against Ardehal strain and this led to widespread viral tenosynovitis in Iran.     

Retrospective study on transmissible viral proventriculitis and chicken proventricular necrosis virus (CPNV) in the UK

ABSTRACT

Chicken proventricular necrosis virus (CPNV) is a recently described birnavirus, which has been proposed to be the cause of transmissible viral proventriculitis (TVP). The understanding of the epidemiology of both the virus and the disease is very limited. A retrospective investigation on TVP and CPNV in broiler chicken submissions from the UK from between 1994 and 2015 was performed with the aims of assessing the longitudinal temporal evolution of TVP and CPNV, and to review the histological proventricular lesions in the studied chickens. Ninety-nine of the 135 included submissions (73.3%) fulfilled the TVP-diagnostic criteria, while the remaining 36 submissions (26.7%) displayed only lymphocytic proventriculitis (LP). The first detection of CPNV by PCR dated from 2009. Results showed a rise in the number of both TVP and positive CPNV RT–PCR submissions from 2009 with a peak in 2013, suggesting that they may be an emerging or re-emerging disease and pathogen, respectively. Twenty-two out of the 99 submissions displaying TVP lesions (22%) and four out of the 36 (11%) submissions with LP gave positive CPNV RT–PCR results, further supporting the association between CPNV and TVP and confirming that CPNV is present in a low proportion of proventriculi that do not fulfil the TVP-diagnostic criteria. In addition, intranuclear inclusion bodies were observed in 22 of the submissions with TVP. The vast majority of these cases (21 of 22, 96%) gave negative CPNV RT–PCR results, raising the question of whether a virus other than CPNV is responsible for some of these TVP-affected cases.

RESEARCH HIGHLIGHTS

• TVP and CPNV have been present in British broilers since at least 1994 and 2009, respectively.

• TVP and CPNV seem to be an emerging and re-emerging disease and pathogen, respectively.

• CPNV was detected in proventriculi with both TVP and LP-lesions.

• Viruses other than CPNV may be responsible for some TVP-affected cases.

     

Highly virulent Marek’s disease virus strains affect T lymphocyte function and viability of splenocytes in commercial meat-type chickens

ABSTRACT

In previous studies, we have demonstrated that very virulent plus Marek’s disease viruses (vv+MDV) are highly immunosuppressive in commercial meat-type chickens. The specific objectives of this work were to evaluate if vv+MDV immunosuppression (MDV-IS) is induced by reduction of lymphocyte responsiveness and/or viability. Three experiments were conducted to (i) compare vv+MDV 686 with a partially attenuated 686-BAC; (ii) compare vv+MDV strains (648A and 686) with vMDV (GA) and vvMDV (Md5); and (iii) compare chickens vaccinated with Md5-BACΔMEQ and with CVI988?+?HVT. In each experiment, spleens were collected at 28–30 days post infection and lymphocytes were isolated and investigated in three ways: their proliferative response to Concanavalin A (ConA) was analysed by MTT proliferation assay; cell death, and expression of CD45 and MHC-I was studied by flow cytometry; and MHC-IA and β-2 microglobulin (B2M) expression was evaluated by real time RT-PCR. Splenocytes of chickens inoculated with vv+MDV were severely impaired to proliferate when exposed to ConA. Furthermore, vv+MDV induced severe splenocyte death that did not occur after infection with v or vvMDV strains. Vaccination with CVI988?+?HVT, and at less level with Md5-BACΔMEQ reduced these negative effects. This is in contrast to our previous results in which Md5-BACΔMEQ but not CVI988?+?HVT protected against MDV-IS suggesting that although cell death and decrease lymphocyte function seem to be related to MDV virulence and certainly will be associated with immunosuppression, they might not fully explain the previously reported MDV-IS.

RESEARCH HIGHLIGHTS

• vv+MDV induces extensive death in splenocytes in meat-type chickens 28–30?dpi.

• vv+MDV impairs lymphocyte function in meat-type chickens 28–30?dpi.

• Vaccination protects against splenocyte death and reduced lymphocyte function.

• Cell lysis and reduced lymphocyte function do not fully explain MDV-IS.

     

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.

     

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).

     

Co-infections of chickens with avian influenza virus H9N2 and Moroccan Italy 02 infectious bronchitis virus: effect on pathogenesis and protection conferred by different vaccination programmes

ABSTRACT

Since the emergence of low pathogenic avian influenza (LPAI) H9N2 viruses in Morocco in 2016, severe respiratory problems have been encountered in the field. Infectious bronchitis virus (IBV) is often detected together with H9N2, suggesting disease exacerbation in cases of co-infections. This hypothesis was therefore tested and confirmed in laboratory conditions using specific-pathogen-free chickens. Most common field vaccine programmes were then tested to compare their efficacies against these two co-infecting agents. IBV γCoV/chicken/Morocco/I38/2014 (Mor-IT02) and LPAI virus A/chicken/Morocco/SF1/2016 (Mor-H9N2) were thus inoculated to commercial chickens. We showed that vaccination with two heterologous IBV vaccines (H120 at day one and 4/91 at day 14 of age) reduced the severity of clinical signs as well as macroscopic lesions after simultaneous experimental challenge. In addition, LPAI H9N2 vaccination was more efficient at day 7 than at day 1 in limiting disease post simultaneous challenge.

RESEARCH HIGHLIGHTS

• Simultaneous challenge with IBV and AIV H9N2 induced higher pathogenicity in SPF birds than inoculation with IBV or AIV H9N2 alone.

• Recommended vaccination programme in commercial broilers to counter Mor-IT02 IBV and LPAIV H9N2 simultaneous infections: IB live vaccine H120 (d1), AIV H9N2 inactivated vaccine (d7), IB live vaccine 4-91 (d14).

     

Effects of a feed additive blend on broilers challenged with heat stress

ABSTRACT

We evaluated a blend of medium-chain fatty acids (MCFA), organic acids, and a polyphenol antioxidant on gut integrity. Eighty Ross Broilers were exposed to 20–22°C (control – normothermic) or to 35–39.5°C (heat stress) for eight hours a day for a period of 1 or 5 days. Birds were fed a standard diet, or a diet supplemented with the test blend. Thereafter, birds were euthanized, and intestinal sections were excised for morphological, morphometric and gene expression analyses. Blood samples were collected for glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GSH-Px) activity and trolox equivalent antioxidant capacity (TEAC) determination. Heart and liver tissues were used to quantify the expression of heat shock proteins 60 and 70 (HSP60 and HSP70, respectively) and inhibitor of kappa light chain gene enhancer in B cells alpha (IKBA). The jejunum was the most sensitive intestinal section, where heat stress modulated the expression of HSP70, of the inflammatory markers IKBA, interleukin 8 (IL-8), interferon gamma (IFNγ), and toll-like receptor 4 (TLR4). Moreover, expression of tight junctions (CLDN1, ZO1 and ZO2) and nutrient transporters (PEPT1 and EAAT3) was modulated especially in the jejunum. In conclusion, the feed additive blend protected intestines during heat stress from the decrease in villus height and crypt depth, and from the increase in villus width. Especially in the jejunum, heat stress played an important role by modulating oxidative stress and inflammation, impairing gut integrity and nutrient transport, and such deleterious effects were alleviated by the feed additive blend.

RESEARCH HIGHLIGHTS

• Jejunum is the most sensitive intestinal segment during heat stress.

• Heat stress affects the expression of tight junctions and nutrient transporters.

• Feed management helps to alleviate the disturbances caused by heat stress.

• A blend of MCFA, organic acids and a polyphenol protects broilers under heat stress.

     

Individual and stable autoantibody repertoires in healthy individuals

In the era towards precision medicine, we here present the individual specific autoantibody signatures of 193 healthy individuals. The self-reactive IgG signatures are stable over time in a way that each individual profile is recognized in longitudinal sampling. The IgG autoantibody reactivity towards an antigen array comprising 335 protein fragments, representing 204 human proteins with potential relevance to autoimmune disorders, was measured in longitudinal plasma samples from 193 healthy individuals. This analysis resulted in unique autoantibody barcodes for each individual that were maintained over one year’s time. The reactivity profiles, or signatures, are person specific in regards to the number of reactivities and antigen specificity. Two independent data sets were consistent in that each healthy individual displayed reactivity towards 0–16 antigens, with a median of six. Subsequently, four selected individuals were profiled on in-house produced high-density protein arrays containing 23,000 protein fragments representing 14,000 unique protein coding genes. Based on a unique, broad and deep longitudinal profiling of autoantibody reactivities, our results demonstrate a unique autoreactive profile in each analyzed healthy individual. The need and interest for broad-ranged and high-resolution molecular profiling of healthy individuals is rising. We have here generated and assessed an initial perspective on the global distribution of the self-reactive IgG repertoire in healthy individuals, by investigating 193 well-characterized healthy individuals.

• Highlights

• A unique longitudinal profiling of autoantibody repertoires in healthy individuals

• Autoantibody profiles are highly individual and stable over time

• All individuals display IgG binding to human protein fragments

• The specificity of disease associated autoantigens needs to be thoroughly characterized

• The identification of a small set of highly reactive autoantigens

• Importance of stringent antigen and sample specific cut-offs for defining reactivity

     

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

     

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.

     

Synergistic effect of a combination of nicarbazin and monensin against coccidiosis in the chicken caused by Eimeria spp.

ABSTRACT

A clinical study was made into the abilities of nicarbazin and monensin and a nicarbazin?+?monensin combination to control Eimeria acervulina, E. maxima, and E. tenella in chickens. When included in the feed, at concentrations of 40?ppm nicarbazin or 40?ppm monensin, these products showed partial efficacy evaluated by daily weight gain (DWG) but no activity judged by daily feed intake (DFI) or feed conversion ratio (FCR). By contrast, the combination of 40?ppm nicarbazin?+?40?ppm monensin provided complete control of infection judged by greater DWG and DFI, and lower FCR. Monensin at a concentration of 40?ppm was ineffective in preventing lesions caused by all three species. Nicarbazin at a concentration of 40?ppm was unable to suppress lesions of E. acervulina and E. maxima but was able to suppress lesions caused by E. tenella. Nicarbazin 40?ppm?+?monensin 40?ppm suppressed lesions of all three species.

RESEARCH HIGHLIGHTS

• Nicarbazin or monensin at 40 ppm gave only partial control of Eimeria spp.

• A combination of 40 ppm nicarbazin + 40 ppm monensin controlled DWG, DFI and FCR.

• Nicarbazin or monensin at 40 ppm did not suppress all Eimeria spp. lesions.

• Nicarbazin 40 ppm + monensin 40 ppm suppressed lesions of all three species.

     

Experimental model of oral transmissible AA amyloidosis in quails

ABSTRACT

In poultry and zoo birds, mass outbreaks of amyloid A (AA) amyloidosis are often reported, and horizontal transmission is considered as one of the causes. However, oral transmission of avian AA amyloidosis in nature has been unclear. In order to clarify the horizontal transmission of avian AA amyloidosis, basic research using an appropriate oral transmission model is necessary. In this study, we developed an oral transmission model of AA amyloidosis using quails, and assessed the oral transmission efficiency of AA amyloidosis in quails and mice. Young quails, adult quails, and young mice received inflammatory stimulation with lipopolysaccharide; simultaneously, homogeneous amyloid fibrils were orally or intravenously administered. By histological examination, induction of amyloidosis by oral or intravenous administration of amyloid was confirmed in all species. Furthermore, both quail and murine AA amyloidosis were orally transmitted in a dose-dependent manner. These results support the possibility of horizontal transmission of avian AA amyloidosis in nature. This model will be able to contribute to the elucidation of spontaneous horizontal transmission of avian AA amyloidosis in the future.

RESEARCH HIGHLIGHTS

• Quail AA amyloidosis was orally transmitted in a dose-dependent manner.

• Oral transmission was less efficient than intravenous transmission.

• In-cage horizontal transmission did not occur during 4-week cohabitation.

• Amyloid deposition in tissues of quail was grossly visible.

     

Biological control as an alternative to synthetic fungicides for the management of grey and blue mould diseases of table grapes: a review

Abstract

Grey and blue mould diseases are among the most important diseases of grapes worldwide. They are causing extensive decay in postharvest grapes. Chemical fungicides remain the primary treatment for managing these diseases. However, consumer’s interest in organic produce, restrictions on chemical use by some countries, and concerns about human and environmental safety have driven research to identify safe and effective alternatives. Among several alternative approaches, the use of biological control agents (BCAs) is getting more acceptance and has been comprehensively studied. This review summarizes the use of BCAs as a postharvest treatment to control the postharvest grey and blue mould of grapes. The review also emphasizes the economic importance of these two major postharvest diseases of grapes. In addition, other non-chemical postharvest treatments, the advantage of an integrated approach and finally problems, challenges, and future trends of the BCAs are described. Several yeasts that have a promising result to control grey and blue mould disease of grapes are thoroughly reviewed. The current market share of BCAs and their future directions on commercialization are also suggested in this review.

• Biocontrols can be a potential control method for postharvest diseases of fruits and vegetables in place of chemical fungicides.

• Antagonistic yeasts have high ability to suppress fungal growth.

• Integrated approach utilizes a combination approaches, which often results in a synergistic effect to control the diseases.

• USA and Europe are currently the largest markets for biocontrol products.

     

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.