HoBi‐Like Virus RNA Detected in Foetuses Following Challenge of Pregnant Cows that had Previously Given Birth to Calves Persistently Infected with Bovine Viral Diarrhoea Virus

The ability of ruminant pestivirus including bovine viral diarrhoea virus (BVDV) and the related emerging pestivirus, HoBi‐like virus, to establish persistent infection (PI) following foetal infection is central to keeping these viruses in circulation. Non‐PI dams carrying BVDV PI calves develop high levels of immunity due constantly viral exposure. A study to determine whether the immunity developed following the generation of a BVDV PI is enough to prevent HoBi‐like virus infection of a subsequent foetus was performed. This study consisted of nine pregnant cows, four had birthed BVDV‐1 PI calves in a previous pregnancy, three cows had birthed BVDV‐2 PIs and two had birthed pestivirus negative calves. From this, six pregnant cows were challenged with HoBi‐like virus about day 85 of gestation (four BVDV‐1 and two BVDV‐2 cows) and three non‐challenged cows (negative control). At the day of challenge, the serum neutralizing titres against the homologous BVDV strains of the first inoculation ranged from 1148 to 5793. At day 6 post‐challenge, HoBi‐like RNA was detected in the serum of all four BVDV‐1 cows but not in the two BVDV‐2 cows. The foetuses harvested from five of the exposed dams (three BVDV‐1 and two BVDV‐2 cows) at day 30 post‐challenge were positive for HoBi‐like virus RNA. The sixth cow, BVDV‐1 cow #541, while pregnant at the time of exposure, had no foetus 30 days after exposure. Foetuses from HoBi‐like virus exposed dams were significantly smaller and lighter than control foetuses. HoBi‐like RNA was detected in samples of all challenged foetuses. The identification of viral RNA in the serum of 4 cows at day 6 post‐challenge, as well viral RNA detection in all foetuses 30 days post‐inoculation, indicates that the foetuses of dams with high antibodies titres against BVDV‐1 or BVDV‐2 would not be protected from challenge with a HoBi‐like virus.     

Pathogenicity of porcine reproductive and respiratory syndrome virus (ORF5 RFLP 1‐7‐4 viruses) in China

Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus that causes reproductive failure in sows and respiratory problems in piglets. PRRSV infection leads to substantial pig mortality and causing huge economic losses so that disease outbreaks caused by the new PRRSV strain from other regions have caused great concern in China. In this study, we analysed the pathogenicity of the novel ORF5 RFLP 1‐7‐4‐like PRRSV strain, named PRRSV‐ZDXYL‐China‐2018‐1 in pigs. The viral challenge test showed that PRRSV‐ZDXYL‐China‐2018‐1 infection can cause persistent fever, moderate dyspnoea, serum viraemia and interstitial pneumonia in piglets. The levels of viral loads in serum and PRRSV‐specific antigen were also detected in lung tissues were used one‐step Taq‐Man RT‐qPCR and Immunohistochemistry, respectively. At 28dpi, the level of specific antibodies was increased among infected piglets. Importantly, the new virus appeared be a moderately virulent isolate with pathogenicity compared to HP‐PRRSV strain LQ (JXA1‐like strain). Histological examination revealed severe monocyte haemorrhage and interstitial pneumonia associated with monocyte infiltration in the lung tissue of pigs infected with PRRSV‐ZDXYL‐China‐2018‐1 and LQ‐JXA1 strains. Immunohistochemistry (IHC) results showed positive brown‐red epithelial cells and macrophages in pig lungs. Therefore, it is critical to establish an effective strategy to control the spread of PRRSV in China.     

Serological relationship between a novel ovine pestivirus and classical swine fever virus

The genus Pestivirus comprises globally distributed members of the family Flaviviridae, which cause severe losses in livestock. The most common species of the genus are bovine viral diarrhoea virus type 1 (BVDV‐1) and type 2 (BVDV‐2), classical swine fever virus (CSFV) and border disease virus (BDV). Recently, a novel ovine pestivirus was repeatedly detected in aborted lamb foetuses on a farm located in the Brescia Province (Italy). Complete genome characterization of this isolate showed that it was highly divergent from known pestivirus species and that it was genetically closely related to CSFV. The aim of this study was to determine the serological relatedness between the identified novel pestivirus and BVDV, BDV and CSFV selected strains for which homologous serum was available, by antigenic characterization performed using cross‐neutralization assays. The serological relatedness was expressed as the coefficient of antigenic similarity (R). Both field and specific antisera raised against the ovine pestivirus neutralized the CSFV reference strain Diepholz with titres significantly higher than those specific for the BDV and BVDV strains. Furthermore, the calculated R values clearly indicated that the novel ovine pestivirus is antigenically more related to CSFV than to ruminant pestiviruses, in agreement with the results of the genomic analysis. This would have severe consequences on CSFV serology in the event of a switch to porcine hosts with implications for CSFV surveillance and porcine health management.     

Inter‐serotype reassortment among epizootic haemorrhagic disease viruses in the United States

First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.     

Serological and molecular epidemiology of foot‐and‐mouth disease viruses in agro‐pastoralist livestock herds in the kachia grazing reserve,Nigeria

The Kachia Grazing Reserve (KGR) is located in Kaduna state in north‐western Nigeria and consists of 6 contiguous blocks housing 744 defined households (HH), all engaged in livestock keeping. It is considered as a homogenous epidemiological unit and a defined study area. In 2012, all cattle and sheep of 40 selected HH were sampled to determine sero‐prevalence of antibodies to foot‐and‐mouth disease virus (FMDV) and of FMDV. The overall sero‐prevalence of antibodies to the non‐structural 3ABC protein (NSP‐3ABC ELISA) was 28.9% (380/1,315) (30.6% cattle; 16.3% sheep), and in 4.5% (62/1,380) (5% cattle; 0.6% sheep) of the examined sera FMD viral RNA could be detected by real‐time RT‐PCR (rRT‐PCR). Additionally, in 2012 and 2014 serum, epithelium and probang samples were collected from cattle in reported FMD outbreaks and the causative FMDVs were molecularly characterized. Approximately half (28/59) of the outbreak sera reacted positive in NSP‐3ABC ELISA, and 88% (52/59) of the outbreak sera contained detectable viral RNA. Overall, antibodies against five FMDV serotypes (O, A, SAT1, SAT2 and SAT3) were detected by solid phase competitive ELISA with combinations of two or more serotypes being common. Of the 21 FMDVs that could be isolated 19 were sequenced and 18 were confirmed as SAT2 (lineage VII) while one was characterized as serotype O (EA‐3 topotype). Phylogenetic analysis revealed a close relationship between Nigerian FMDV strains and strains in this region and even with strains in North‐Africa. Our findings indicate that FMD constitutes an endemic health problem to cattle rearing in the agro‐pastoralist community in the KGR and that the KGR is not a closed epidemiological unit. Insight into the local FMDV epidemiology and in the circulating FMDV serotypes/strains is of support to the relevant authorities in Nigeria when considering the need for an FMD control policy to improve animal production in grazing reserves.     

Beyond Rabies: Are Free‐Ranging Skunks (Mephitis mephitis) in British Columbia Reservoirs of Emerging Infection?

Wild animal reservoirs are an important source of emerging and zoonotic infection. Skunks (Mephitis mephitis) are a reservoir of skunk strain rabies virus in Canada, with the exception of some areas including the province of British Columbia (BC). Beyond rabies, the reservoir status of skunks for emerging and zoonotic pathogens in BC is unknown. From March 2011 to February 2015, 50 free‐ranging skunks were necropsied and tested for 4 pathogens: influenza A, Aleutian disease virus (ADV), Leptospira spp. and Salmonella spp. Two skunks (4%) with respiratory disease caused by influenza A (H1N1) pdm09 were detected during the human flu season suggesting that skunks may represent a target population for reverse zoonosis of this strain of influenza A virus. High prevalence of ADV infection was detected (43/50, 86%). Two of the infected skunks exhibited Aleutian disease (AD) suggesting that skunks act as both a reservoir and a target population for the virus. Most studies of ADV have focused on the potential for infection of free‐ranging species living near mink farms. Our study suggests that urban skunks may be a primary host for the virus independent of domestic mink. Whether skunks act as a reservoir of ADV infection for other peridomestic species will depend on host specificity of the viral strains. Leptospira interrogans was detected in 18% (9/49) of the skunks. Identification of the serovar(s) detected is needed to determine any public health risk of leptospirosis following exposure to infected skunks. Salmonella spp. was isolated from three of 43 skunks (7%), specifically S. Typhimurium, S. Muenchen and S. Enteritidis. These serotypes cause disease in humans, but the low prevalence of infection suggests there is a low risk for zoonotic transmission.     

Insights into the evolution of the new variant rabbit haemorrhagic disease virus (GI.2) and the identification of novel recombinant strains

Rabbit haemorrhagic disease (RHD ) is a viral disease that affects the European rabbit. RHD was detected in 1984 in China and rapidly disseminated worldwide causing a severe decline in wild rabbit populations. The aetiological agent, rabbit haemorrhagic disease virus (RHDV ), is an RNA virus of the family Caliciviridae , genus Lagovirus . Pathogenic (G1‐G6 or variants GI .1a‐GI .1d) and non‐pathogenic strains (GI .4) have been characterized. In 2010, a new variant of RHDV , RHDV 2/RHDV b/GI .2, was detected in France. GI .2 arrived to the Iberian Peninsula in 2011, and several recombination events were reported. Here, we sequenced full genomes of 19 samples collected in Portugal between 2014 and 2016. New GI .2 recombinant strains were detected, including triple recombinants. These recombinants possess a non‐structural protein p16 related to a non‐pathogenic strain. Evolutionary analyses were conducted on GI .2 VP 60 sequences. Estimated time to the most recent common ancestor (tMRCA ) suggests an emergence of GI .2 in July 2008, not distant from its first detection in 2010. This is the first study on GI .2 evolution and highlights the need of continued monitoring and characterization of complete genome sequences when studying lagoviruses’ evolution.     

Development of Real‐Time RT‐PCR Assays for Detection and Typing of Epizootic Haemorrhagic Disease Virus

Epizootic haemorrhagic disease virus (EHDV) is an emerging arboviral pathogen of wild and domestic ruminants worldwide. It is closely related to bluetongue virus (BTV) and is transmitted by adult females of competent Culicoides vector species. The EHDV genome consists of ten linear double‐stranded (ds)RNA segments, encoding five non‐structural and seven structural proteins. Genome‐segment reassortment contributes to a high level of genetic variation in individual virus strains, particularly in the areas where multiple and distinct virus lineages co‐circulate. In spite of the relatively close relationship between BTV and EHDV herd‐immunity to BTV does not appear to protect against the introduction and infection of animals by EHDV. Although EHDV can cause up to 80% morbidity in affected animals, vaccination with the homologous EHDV serotype is protective. Outer‐capsid protein VP2, encoded by Seg‐2, is the most variable of the EHDV proteins and determines both the specificity of reactions with neutralizing antibodies and consequently the identity of the eight EHDV serotypes. In contrast, VP6 (the viral helicase), encoded by Seg‐9, is highly conserved, representing a virus species/serogroup‐specific antigen. We report the development and evaluation of quantitative (q)RT‐PCR assays targeting EHDV Seg‐9 that can detect all EHDV strains (regardless of geographic origin/topotype/serotype), as well as type‐specific assays targeting Seg‐2 of the eight EHDV serotypes. The assays were evaluated using orbivirus isolates from the ‘Orbivirus reference collection’ (ORC) at The Pirbright Institute and were shown to be EHDV pan‐reactive or type‐specific. They can be used for rapid, sensitive and reliable detection and identification (typing) of EHDV RNA from infected blood, tissue samples, homogenized Culicoides, or tissue culture supernatant. None of the assays detected RNA from closely related but heterologous orbiviruses, or from uninfected host animals or cell cultures. The techniques presented could be used for both surveillance and vaccine matching (serotype identification) as part of control strategies for incursions in wild and domestic animal species.     

Evaluation of an IGM‐specific ELISA for early detection of bluetongue virus infections in domestic ruminants sera

Competitive‐ELISA (c‐ELISA) is the most widely used serological test for the detection of Bluetongue virus (BTV) viral protein 7 (VP7) antibodies (Ab). However, these BTV c‐ELISAs cannot to distinguish between IgG and IgM. IgM Ab are generated shortly after the primary immune response against an infectious agent, indicating a recent infection or exposure to antigens, such as after vaccination. Because the BTV genome or anti‐VP7 Ab can be detected in ruminant blood months after infection, BTV diagnostic tools cannot discriminate between recent and old infections. In this study, we evaluated an IgM‐capture ELISA prototype to detect ruminant anti‐BTV VP7 IgM on 1,650 serum samples from cattle, sheep, or goats. Animals were BTV‐naive, infected, or/and vaccinated with BTV‐1, ‐2, ‐4, ‐8, ‐9, ‐16, or ‐27, and we also included 30 sera from cattle infected with the Epizootic haemorrhagic disease virus (EHDV) serotype 6. Results demonstrated that this ELISA kit is specific and can detect the presence of IgM with satisfactory diagnostic specificity and sensitivity from 1 to 5 weeks after BTV infection in domestic ruminants (for goats and cattle; for sheep, at least up to 24 days). The peak of anti‐VP7 IgM was reached when the level of infectious viruses and BTV RNA in blood were the highest. The possibility of detecting BTV‐RNA in IgM‐positive sera allows the amplification and sequencing of the partial RNA segment 2 (encoding the serotype specific to VP2) to determine the causative BTV serotype/strain. Therefore, BTV IgM ELISA can detect the introduction of BTV (or EHDV) in an area with BTV‐seropositive domestic animals regardless of their serological BTV status. This approach may also be of particular interest for retrospective epidemiological studies on frozen serum samples.     

Detection of border disease virus in Mexican cattle

The genus Pestivirus within Flaviviridae is comprised of four recognized species, namely, bovine viral diarrhoea virus 1 (BVDV ‐1), bovine viral diarrhoea virus 2 (BVDV ‐2), border disease virus (BDV ) and classical swine fever virus (CSFV ). BDV , while primarily infecting sheep and goats, has also been reported in cattle and wild animals. Infections of sheep and goats result in economic loss due to abortions and the birth of persistently infected animals that have poor production and reduced life expectancy. In this study, we report the detection of BDV in cattle serum collected as part of pestivirus surveillance programme from six regions of Mexico, where a 67.1% of BVDV seroprevalence was calculated previously. Phylogenetic analyses based on comparison of the 5′UTR region typed the Mexican strains as BDV ‐1. Border disease (BD ) is listed as an exotic disease in Mexico, and the origin of BDV found in these cattle is unclear. This is the first identification of BDV in Mexican cattle.     

Endemic outbreaks due to the re‐emergence of classical swine fever after accidental introduction of modified live LOM vaccine on Jeju Island,South Korea

After the unintentional vaccination of the LOM vaccine strain in 2014, classical swine fever virus (CSFV) reemerged in naïve pig herds on Jeju Island, South Korea, which had been a CSF‐free region with a non‐vaccination policy for a decade. Since the re‐emergence, endemic outbreaks of CSFV have occurred in the island, causing enormous damage to provincial pig farms. The present study reports the complete genome sequences and molecular characterization of the LOM‐derived field CSFV strains responsible for the current outbreaks on Jeju Island. The emergent Jeju LOM‐derived isolates shared 98.9%–99.7% and 98.7%–99.0% nucleotide sequence identity at the E‐gene and whole‐genome levels compared to the LOM vaccine strain respectively. Genetic and phylogenetic analyses indicated that the CSFV field isolates were closest to the LOM strains, but appeared to have undergone substantial evolution. The total number of nucleotide and amino acid differences between the LOM vaccine strain and LOM‐derived field isolates ranged from 111 and 28 to 148 and 42. These variations were found to be widely distributed throughout the genome and particularly accumulated in non‐structural proteins, which might be associated with the potential for LOM to revert to its original low pathogenic form and subsequent horizontal transmission in Jeju swine herds. These data improve our knowledge regarding safety of the LOM vaccine and inherent risk of reversion to natural virulence in host animals.     

A strain‐specific multiplex RT‐PCR for Australian rabbit haemorrhagic disease viruses uncovers a new recombinant virus variant in rabbits and hares

Rabbit haemorrhagic disease virus (RHDV , or GI .1) is a calicivirus in the genus Lagovirus that has been widely utilized in Australia as a biological control agent for the management of overabundant wild European rabbit (Oryctolagus cuniculus ) populations since 1996. Recently, two exotic incursions of pathogenic lagoviruses have been reported in Australia; GI .1a‐Aus, previously called RHDV a‐Aus, is a GI .1a virus detected in January 2014, and the novel lagovirus GI .2 (previously known as RHDV 2). Furthermore, an additional GI .1a strain, GI .1a‐K5 (also known as 08Q712), was released nationwide in March 2017 as a supplementary tool for wild rabbit management. To discriminate between these lagoviruses, a highly sensitive strain‐specific multiplex RT ‐PCR assay was developed, which allows fast, cost‐effective and sensitive detection of the four pathogenic lagoviruses currently known to be circulating in Australia. In addition, we developed a universal RT ‐qPCR assay to be used in conjunction with the multiplex assay that broadly detects all four viruses and facilitates quantification of viral RNA load in samples. These assays enable rapid detection, identification and quantification of pathogenic lagoviruses in the Australian context. Using these assays, a novel recombinant lagovirus was detected in rabbit tissue samples, which contained the non‐structural genes of GI .1a‐Aus and the structural genes of GI .2. This variant was also recovered from the liver of a European brown hare (Lepus europaeus ). The impact of this novel recombinant on Australian wild lagomorph populations and its competitiveness in relation to circulating field strains, particularly GI .2, requires further studies.     

Bluetongue Virus RNA Detection by Real‐Time RT‐PCR in Post‐Vaccination Samples from Cattle

Bluetongue virus serotype 8 (BTV‐8) was responsible for a large outbreak among European ruminant populations in 2006–2009. In spring 2008, a massive vaccination campaign was undertaken, leading to the progressive disappearance of the virus. During surveillance programmes in Western Europe in 2010–2011, a low but significant number of animals were found weakly positive using BTV‐specific real‐time RT‐PCR, raising questions about a possible low level of virus circulation. An interference of the BTV‐8 inactivated vaccine on the result of the real‐time RT‐PCR was also hypothesized. Several studies specifically addressed the potential association between a recent vaccination and BTV‐8 RNA detection in the blood of sheep. Results were contradictory and cattles were not investigated. To enlighten this point, a large study was performed to determine the risks of detection of bluetongue vaccine‐associated RNA in the blood and spleen of cattle using real‐time RT‐PCR. Overall, the results presented clearly demonstrate that vaccine viral RNA can reach the blood circulation in sufficient amounts to be detected by real‐time RT‐PCR in cattle. This BTV‐8 vaccine RNA carriage appears as short lasting.     

Sequences of Genes Encoding Type‐Specific and Group‐Specific Antigens of an Indian Isolate of Bluetongue Virus Serotype 10 (BTV‐10) and Implications for their Origin

Bluetongue, a transboundary disease, is endemic in several tropical countries and is caused by bluetongue virus (BTV). The origin and movement of BTV can be predicted by comparing nucleotide sequences of its segmented RNA genome. Such analyses have been useful in evaluating the source of the virus responsible for recent incursion of BTV into previously unreported areas. Besides several serotypes, genetically related BTV strains circulate in each endemic area, but such clusters of strains have been reported to be distinct from one geographical region to another. We obtained partial or complete sequences of the open reading frames encoded by VP2, VP6, VP7, NS1 and NS2 genes of a BTV‐10 isolate of India and compared them with other BTV‐10 sequences available in public database. Sequences of all the five genes showed >99% identity to BTV‐10 prototype, vaccine strain and vaccine‐like virus isolates from the USA. Our results suggest that Indian BTV‐10 virus analysed in this study possibly originated from the United States.     

First experimental proof of Rotavirus A (RVA) genotype G18P[17] inducing the clinical presentation of ‘young pigeon disease syndrome’ (YPDS) in domestic pigeons (Columba livia)

Young pigeon disease syndrome (YPDS) is characterized as a seasonally occurring, acute and primarily enteric medical condition of mainly juvenile domestic pigeons (Columba livia) with highly variable mortality reaching more than 50%. Although the syndrome has been known in Europe for almost three decades, its aetiology remains largely obscure. Recently, a previously unknown pigeon‐associated clade of Rotavirus A (RVA) genotype G18P[17] was detected in Europe and Australia in association with fatal diseases resembling YPDS. Here we show for the first time, that peroral inoculation of healthy juvenile homing pigeons with two genetically different cell culture isolates of RVA G18P[17] (10^6.3 foci‐forming units per bird) induces an acute and self‐limiting YPDS‐like disease in all infected birds. Clinical signs included regurgitation, diarrhoea, congested crops, anorexia and weight loss, as described for naturally RVA‐infected pigeons. In agreement with the original outbreaks, RVA isolate DR‐7 induced more pronounced clinical signs as compared to isolate DR‐5, indicating strain‐dependent virulence factors to contribute to variable disease outcomes observed in the field. All inoculated birds developed rotavirus‐reactive antibodies starting at seven days after inoculation. High levels of viral RNA and infectious virus were detectable in cloacal swabs and faecal samples already three days after inoculation. While shedding of infectious virus subsided within few days, moderate viral RNA levels were still detectable in cloacal swabs, faeces, and tissue samples at the end of the experiment three weeks after inoculation. Histopathological analysis at this time point revealed inflammatory lesions in spleens and livers of pigeons from both infected groups. In summary, we fulfilled Henle‐Koch's postulates and confirmed RVA G18P[17] as a primary cause of YPDS‐like diseases in domestic pigeons. By establishing an infection model, we provide a crucial tool for future research, such as identification of transmission routes and establishing vaccination regimes.     

Exposure of free‐ranging capybaras (Hydrochoerus hydrochaeris) to the vaccinia virus

The aim of this study was to evaluate the possibility of free‐ranging animals/hunting dogs as sources of infection in the vaccinia virus (VACV) transmission chain. Serological, cell culture and molecular assays were conducted in 56 free‐ranging animals and 22 hunting dogs. ELISA/neutralizing assays showed that two (2.5%) capybaras (Hydrochoerus hydrochaeris) had anti‐OPV positive antibodies, while all samples tested negative through PCR/cell culture. After being hit by cars on roads, capybaras that exhibited neither clinical signs nor any association with bovine outbreaks had neutralizing antibodies against the Orthopoxvirus, as detected through plaque‐reduction neutralizing tests and ELISA. Evidence exists regarding peridomestic capybaras acting as a source of the virus and serving as a link between wild and urban environments, thus contributing to viral maintenance.     

Early Detection of Foot‐And‐Mouth Disease Virus from Infected Cattle Using A Dry Filter Air Sampling System

Foot‐and‐mouth disease (FMD) is a highly contagious livestock disease of high economic impact. Early detection of FMD virus (FMDV) is fundamental for rapid outbreak control. Air sampling collection has been demonstrated as a useful technique for detection of FMDV RNA in infected animals, related to the aerogenous nature of the virus. In the current study, air from rooms housing individual (n = 17) or two groups (n = 4) of cattle experimentally infected with FDMV A24 Cruzeiro of different virulence levels was sampled to assess the feasibility of applying air sampling as a non‐invasive, screening tool to identify sources of FMDV infection. Detection of FMDV RNA in air was compared with first detection of clinical signs and FMDV RNA levels in serum and oral fluid. FMDV RNA was detected in room air samples 1–3 days prior (seven animals) or on the same day (four animals) as the appearance of clinical signs in 11 of 12 individually housed cattle. Only in one case clinical signs preceded detection in air samples by one day. Overall, viral RNA in oral fluid or serum preceded detection in air samples by 1–2 days. Six individually housed animals inoculated with attenuated strains did not show clinical signs, but virus was detected in air in one of these cases 3 days prior to first detection in oral fluid. In groups of four cattle housed together, air detection always preceded appearance of clinical signs by 1–2 days and coincided more often with viral shedding in oral fluid than virus in blood. These data confirm that air sampling is an effective non‐invasive screening method for detecting FMDV infection in confined to enclosed spaces (e.g. auction barns, milking parlours). This technology could be a useful tool as part of a surveillance strategy during FMD prevention, control or eradication efforts.     

Identification of six novel capsular polysaccharide loci (NCL) from Streptococcus suis multidrug resistant non‐typeable strains and the pathogenic characteristic of strains carrying new NCLs

Streptococcus suis is a major swine pathogen and an important zoonotic agent worldwide. At least nine serotypes can infect human so far. Although 29 serotypes (1–19, 21, 23–25, 27–31 and 1/2) strains are considered as authentic S. suis, a novel variant serotype Chz and strains carrying 20 novel capsular polysaccharide loci (NCL) have been identified recently. However, information about pathogenic and antimicrobial resistance characteristics of strains carrying NCLs is still unavailable. In this study, we identified six new NCLs (designated as NCL21‐26) from 35 non‐typeable S. suis strains by agglutination tests and whole genome sequencing analysis. Further analysis of the genetic context of NCL25 and NCL26 showed a mosaic structure of the capsular polysaccharide loci. NCL25 exhibited considerable similarity to that of serotypes 10 and 11, and NCL26 shared similarity to that of serotype 9 and NCL4. Antimicrobial susceptibility testing demonstrated that strains carrying NCL21‐26 were all resistant to clindamycin, lincomycin, erythromycin, tilmicosin and tetracycline. Animal infection experiments showed that the virulence of NCL26 strain NJ1112 isolated from a disease pig was similar to that of S. suis serotype 2 virulent strain SC070731 in both zebrafish and mouse infection models, highlighting the necessity for surveillance of strains belonging to NCL26. We also developed a multiplex PCR assay to detect NCL21‐26 strains. Our findings expand the views of genetic diversity of S. suis capsular polysaccharide loci and S. suis pathogenic characteristic.