Equine coronavirus infection and replication in equine intestinal enteroids.

In this study, equine intestinal enteroids (EIEs) were generated from the duodenum, jejunum, and ileum and inoculated with equine coronavirus (ECoV) to investigate their suitability as in vitro models with which to study ECoV infection. Immunohistochemistry revealed that the EIEs were composed of various cell types expressed in vivo in the intestinal epithelium. Quantitative reverse-transcription PCR (qRT-PCR) and virus titration showed that ECoV had infected and replicated in the EIEs.

Performance of a microfluidic immunofluorescence assay kit for equine influenza virus antigen detection.

Equine influenza virus (EIV) infection is one of the most important respiratory diseases in the equine industry around the world. Rapid diagnosis, facilitated by point-of-care testing, is essential to implement movement restrictions and control disease outbreaks. This study evaluated a microfluidic immunofluorescence assay kit, which detects influenza virus and SARS-CoV-2 antigens in human specimens with a 12 min turnaround time, for its potential use in detecting EIV.

Prevalence of serum and salivary virus-neutralizing antibodies against equine coronavirus in four riding stables in Japan.

To assess the prevalence of equine coronavirus infection in riding horses, virus-neutralizing tests were performed on serum and saliva samples collected at four facilities in Japan. Seropositivity rates ranged from 79.2% to 94.

Comparison of 4 agar gel immunodiffusion kits for serologic detection of equine infectious anemia virus antibodies.

Using 85 sera collected from horses that had been experimentally infected with equine infectious anemia virus (EIAV) and 200 field sera collected from racehorses in Japan, we compared 4 agar gel immunodiffusion (AGID) kits for serologic detection of EIAV antibodies from Idexx, VMRD, IDvet, and the National Engineering Research Center of Veterinary Biologics, China (NECVB). The positive control lines were sufficiently clear in all kits for evaluation to be made, with slight differences in sharpness: NECVB was the sharpest, followed by VMRD, IDvet, and Idexx. The test results for all 285 samples agreed among the 4 kits, with 62 positives and 223 negatives.

Antigenic comparison of H3N8 equine influenza viruses belonging to Florida sublineage clade 1 between vaccine strains and North American strains isolated in 2021-2022.

Equine influenza virus strains of Florida sublineage clade 1 (Fc1) have been circulating in North America. In this study, virus neutralization assays were performed to evaluate antigenic differences between Fc1 vaccine strains and North American Fc1 strains isolated in 2021-2022, using equine antisera against A/equine/South Africa/4/2003 (a vaccine strain recommended by the World Organisation for Animal Health) and A/equine/Ibaraki/1/2007 (a Japanese vaccine strain). Antibody titers against four North American Fc1 strains isolated in 2021-2022 were comparable to those against the homologous vaccine strains.

Surveillance of Getah virus in mosquitoes and racehorses from 2016 to 2019 at a training center in Ibaraki Prefecture, Japan, a site of several previous Getah virus outbreaks.

Mosquitoes and EDTA-treated blood samples from febrile racehorses were investigated for Getah virus infection from 2016 to 2019 at the Miho Training Center, where several outbreaks of Getah virus have occurred. We collected 5557 mosquitoes and 331 blood samples from febrile horses in this study. The most frequently captured mosquito species was Culex tritaeniorhynchus (51.

Experimental challenge of horses after prime-boost immunization with a modified live equid alphaherpesvirus 1 vaccine administered by two different routes.

The immune response and protective efficacy of a modified equid alphaherpesvirus 1 (EHV-1) vaccine administered by two different routes were tested in horses. Horses that received intramuscular (IM) priming and an intranasal (IN) booster with a 28-day interval (IM-IN group [n = 6]), IN priming and IM booster (IN-IM group [n = 5]), or no vaccination (control group [n = 6]) were challenged with EHV-1 strain 10-I-224 28 days after the second vaccination. Both vaccinated groups had significantly higher serum virus-neutralizing titers than the control group, with increased levels of serum IgGa, IgGb, and IgA antibodies (p < 0.

Protective efficacy of a reverse genetics-derived inactivated vaccine against equine influenza virus in horses.

Updating vaccine strains is essential to control equine influenza. We evaluated the protective efficacy of an inactivated equine influenza vaccine derived from viruses generated by reverse genetics (RG) in horses in an experimental viral challenge study. Wild-type (WT) virus (A/equine/Tipperary/1/2019) and virus generated by RG (consisting of hemagglutinin and neuraminidase genes from A/equine/Tipperary/1/2019 and six other genes from high-growth A/Puerto Rico/8/34) were inactivated by formalin for vaccine use.

Serosurveillance of equine coronavirus infection among Thoroughbreds in Japan.

Background: Equine coronavirus (ECoV) causes fever, lethargy, anorexia and gastrointestinal signs in horses. There has been limited information about the prevalence and seasonality of ECoV among Thoroughbreds in Japan.

Objectives: To understand the epidemiology and to evaluate the potential risk of ECoV infection to the horse industry in Japan.

Distribution of equine coronavirus RNA in the intestinal and respiratory tracts of experimentally infected horses.

Equine coronavirus (ECoV) causes pyrexia, anorexia, lethargy, and sometimes diarrhoea. Infected horses excrete the virus in their faeces, and ECoV is also detected in nasal samples from febrile horses. However, details about ECoV infection sites in the intestinal and respiratory tracts are lacking.

Antibody Responses to a Reverse Genetics-Derived Bivalent Inactivated Equine Influenza Vaccine in Thoroughbred Horses.

Updating vaccine strains is important to control equine influenza (EI). Previously, we reported that a monovalent inactivated EI vaccine derived from a virus generated by reverse genetics (RG) elicited immunogenicity in horses. In the present study, we compared antibody responses to a bivalent inactivated EI vaccine generated by RG and a commercially available bivalent inactivated EI (CO) vaccine derived from wild-type equine influenza viruses in Thoroughbred horses.

Persistence of virus-neutralizing antibodies in horses inoculated with two doses of a live equine herpesvirus type 1 vaccine with different vaccination intervals.

The antibody response in horses inoculated with 2 doses of a live equine herpesvirus type 1 vaccine with different vaccination intervals (1 to 3 months) was evaluated with regard to the persistence of virus-neutralizing (VN) antibodies. The durations for which the geometric mean VN titers were maintained significantly higher than those before the first vaccination (P<0.05) were up to 5 months in horses that received the vaccination with a 1-month interval (n=17) and 7 months for those that received it with a 2-month (n=17) or 3-month interval (n=14 or 17).

Decreased Virus-Neutralizing Antibodies Against Equine Herpesvirus type 1 In Nasal Secretions of Horses After 12-hour Transportation.

This study evaluated the effects of 12-hour transportation on immune responses to equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4). Possible replication of EHV-1 and EHV-4 was monitored by real-time PCR of nasal swabs and peripheral blood mononuclear cells (PBMCs), and changes in systemic and mucosal antibodies were investigated. Six healthy Thoroughbreds with transport experience were transported in commercial trucks, repeating the same three-hour route four times.

Outbreak of equine coronavirus infection among riding horses in Tokyo, Japan.

In 2020, an outbreak of equine coronavirus (ECoV) infection occurred among 41 horses at a riding stable in Tokyo, Japan. This stable had 16 Thoroughbreds and 25 horses of other breeds, including Andalusians, ponies and miniature horses. Fifteen horses (37 %) showed mild clinical signs such as fever, lethargy, anorexia and diarrhoea, and they recovered within 3 days of onset.

Antigenic differences between equine influenza virus vaccine strains and Florida sublineage clade 1 strains isolated in Europe in 2019.

From late 2018 to 2019, equine influenza virus (EIV) strains of Florida sublineage clade 1 (Fc1), which had until then been circulating mainly in the United States, suddenly spread across Europe causing many outbreaks, and Florida sublineage clade 2 (Fc2) strains, which had been circulating mainly in Europe, have not been detected in Europe since 2018. Since 2010, the World Organisation for Animal Health (OIE) has recommended that EIV vaccines contain an Fc1 strain that is like A/equine/South Africa/4/2003 or A/equine/Ohio/2003. Accordingly, Japanese vaccines contain A/equine/Ibaraki/1/2007 as the Fc1 strain.

Evaluation of Antibody Response in Horses After Vaccination With an Inactivated Getah Virus Vaccine Using an Accelerated Immunization Schedule.

Antibody response in horses after accelerated-schedule Getah virus vaccination was evaluated for its potential adoption during outbreaks. One-year-old Thoroughbred horses received two doses of priming vaccinations following an accelerated schedule (accelerated group: 14-day interval, n = 30) or the conventional schedule (control group: 28-day interval, n = 30). At Day 14, both groups showed similar seropositive rates (66.

Growth properties and immunogenicity of a virus generated by reverse genetics for an inactivated equine influenza vaccine.

Background: Keeping vaccine strains up to date is the key to controlling equine influenza (EI). Viruses generated by reverse genetics (RG) are likely to be effective for quickly updating a vaccine strain.

Objectives: To evaluate the growth properties of an RG virus in embryonated chicken eggs, and to evaluate antibody responses to a formalin-inactivated vaccine derived from the RG virus in Thoroughbred horses.

Antibody Responses Against Equine Influenza Virus Induced by Concurrent and by Consecutive Use of an Inactivated Equine Influenza Virus Vaccine and a Modified Live Equine Herpesvirus Type 1 Vaccine in Thoroughbred Racehorses.

An inactivated equine influenza virus (EIV) vaccine and a live equine herpesvirus type 1 (EHV-1) vaccine are usually administered concurrently to Thoroughbred racehorses in Japan. The objective of this study was to evaluate whether concurrent administration of an inactivated EIV vaccine and a live EHV-1 vaccine in Thoroughbred racehorses influences the antibody response against EIV. We compared the antibody response against EIV in horses administered both vaccines on the same day (Group A; n = 27) and the response in horses administered an inactivated EIV vaccine first and then a live EHV-1 vaccine 1-2 weeks later (Group B; n = 20).

Evaluation of cobas Influenza A/B & RSV Test for Diagnosis of Equine Influenza.

A rapid and sensitive diagnostic method is needed to help prevent the spread of equine influenza virus. The cobas Influenza A/B & RSV test for the cobas Liat system (Roche Diagnostics) is based on real-time reverse transcription polymerase chain reaction and is designed to broadly detect influenza A virus RNA within 20 minutes. It detected a broad range of equine influenza virus strains, and detected equine influenza virus RNA from nasal swabs of infected horses at the same level as real-time reverse transcription polymerase chain reaction, although it returned some invalid results (7.

Isolation and characterization of a rare group A rotavirus G13P[18] strain from a diarrhoeic foal in Japan.

A rare genotype G13P[18] group A rotavirus (RVA/Horse-tc/JPN/MK9/2019/G13P[18]) was isolated from a diarrhoeic foal for the first time in 28 years. The genotype constellation of the virus was assigned to G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11 and was the same as that of the first isolated strain, RVA/Horse-tc/GBR/L338/1991/G13P[18]. Phylogenetic analysis suggests that the virus is related to RVA/Horse-tc/GBR/L338/1991/G13P[18] and is distant from typical equine rotaviruses of the G3P[12] and G14P[12] genotypes.

Establishment of an enzyme-linked immunosorbent assay for Getah virus infection in horses using a 20-mer synthetic peptide for the E2 glycoprotein as an antigen.

An enzyme-linked immunosorbent assay (ELISA) using a synthetic peptide for the E2 glycoprotein was developed for the serodiagnosis of Getah virus infection in horses. To identify an immunogenic epitope, a series of 20-mer peptides (n = 22) for the E2 protein was screened with pooled sera from horses infected with Getah virus. Peptide P11 (PTEEEIDMHTPPDIPDITLL) showed the strongest reaction.

Mutated influenza A virus exhibiting reduced susceptibility to baloxavir marboxil from an experimentally infected horse.

Baloxavir marboxil (BXM), an inhibitor of the cap-dependent endonuclease of the influenza virus polymerase acidic protein (PA), exerts an antiviral effect against influenza A virus. It has been available in Japan since March 2018. This study evaluated the antiviral efficacy of BXM against equine influenza A virus (EIV) by an experimental challenge study using horses.

Epizootiological investigation of equine herpesvirus type 1 infection among Japanese racehorses before and after the replacement of an inactivated vaccine with a modified live vaccine.

Background: Equine herpesvirus type 1 (EHV-1) infection is a major cause of pyrexias in winter among Japanese racehorses. In 2014-2015, the Japan Racing Association (JRA) changed the EHV-1 vaccine from an inactivated vaccine to a live vaccine (both produced by Nisseiken). To evaluate the effect of changing the vaccines, the capacities of these vaccines to induce virus-neutralizing (VN) antibodies were compared, and an epizootiological investigation of EHV-1 was performed at the JRA Ritto Training Center during epizootic periods from 2010-2011 to 2016-2017.

A single amino acid change in hemagglutinin reduces the cross-reactivity of antiserum against an equine influenza vaccine strain.

Equine influenza virus is an important pathogen for the horse industry because of its economic impact, and vaccination is a key control measure. Our previous work suggested that a mutation at position 144 in the hemagglutinin of Florida sublineage clade 2 viruses reduces the cross-neutralizing activity of antiserum against a former vaccine strain. To confirm this suggestion, here, we generated viruses by reverse genetics.

Development of an enzyme-linked immunosorbent assay for Getah virus infection in horses using recombinant E2 protein as an antigen.

Getah virus causes fever, skin eruptions, and limb edema in horses. For a high-throughput and time-saving method for serodiagnosis, we explored immunogenic antigens of Getah virus, and established an enzyme-linked immunosorbent assay (ELISA) using a recombinant protein. Western blot analysis using sera from infected horses showed strong reaction with viral antigens around 46 kDa corresponding to E1 or E2 glycoproteins.