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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). The vaccination program with the 2-month interval was the most effective in maintaining VN antibodies for a long duration with the smallest gap of antibody decline between the first and second vaccinations., (©2021 The Japanese Society of Equine Science.)

Aim: To estimate the frequency of infection with equine herpesvirus type-1 (EHV-1) among horses from the central North Island of New Zealand, including the frequency of detection of the D 752 genotype. Methods: Samples of retropharyngeal lymph nodes (RLN) and submandibular lymph nodes (SLN) were dissected from the heads of 63 horses that were humanely killed for various unrelated reasons between March and November 2015. DNA extracted from these tissues was subjected to enrichment for EHV-1 sequences by hybridisation with biotin-labelled EHV-1 specific probe, followed by recovery of EHV-1 sequences on streptavidin-coated magnetic beads. Enriched samples were tested for the presence of EHV-1 using nested quantitative real-time PCR. The EHV-1 amplicons were sequenced to determine the genotype of the virus. Results: The median age of the horses was 6 (min 2, max 30) years, and 47/63 (75%) were Thoroughbreds. EHV-1 DNA was detected in RLN samples from 6/63 (10%) horses, and three of these horses were also positive for EHV-1 DNA in SLN. The remaining horses were negative for EHV-1 DNA in both RLN and SLN samples. The N 752 genotype was detected in all positive samples and the D 752 genotype was not detected in any of the samples. Conclusions: EHV-1 continues to circulate among horses in New Zealand. The frequency of latent EHV-1 infection among sampled horses may have been underestimated due to the sensitivity limit of the assay or because of the limited anatomical sites sampled in the study. Lack of detection of the D 752 genotype suggests that infection with this genotype is not common in horses in New Zealand. Clinical Relevance: If live animals are tested for EHV-1 using SLN biopsy it should be kept in mind that negative results do not rule out the presence of latent EHV-1 infection at other sites inaccessible for testing. The RLN appear to be the preferred sample for detection of EHV-1 DNA in horses following recent euthanasia.

The herpesviruses infections in equides are caused by five different serotypes of viruses, belonging to family Herpesviridae. The goal of this study was to conduct a seroepidemiological investigation of equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) in horses and donkeys raised in two provinces and their villages in northeastern Turkey. A total of 666 samples from 423 horses and 243 donkeys that were not immunized against these infections were tested with ELISA. While 52.48% of tested horse sera was found to carry specific antibodies to EHV-1, 83.69% of these serums were found to carry specific antibodies to EHV-4. 51. Eighty-five percent of analyzed donkey samples tested positive for EHV-1 and 64.20% of these samples tested positive for EHV-4 antibodies. When the horse and donkey samples were evaluated together, 52.25% were seropositive for EHV-1 and 76.58% were seropositive for EHV-4. This study showed that EHV-1 and EHV-4 infections are quite common in the horses and donkeys being raised in the areas where the study was carried out. In addition, since the area where the study was carried out in the borders of Armenia and Georgia, the high level of seropositive results for these infections leads to the conclusion that we should consider the risk of diseases spreading to neighboring countries. This is the first study to serologically identify EHV-1 and EHV-4 infections in donkeys raised in Turkey.