Bovine alphaherpesvirus 1 and 5 in semen from bulls presenting genital lesions under field conditions in Brazil

ABSTRACT Bovine alphaherpesviruses 1 and 5 (BoHV-1/5) are main pathogens of respiratory, reproductive and neurological diseases in cattle. The aim of this study was to investigate the frequency of neutralizing antibodies against BoHV-1/5 in serum samples and to detect viral DNA in semen of bulls from beef cattle farms located in RS. A total of 372 serum and semen sample from bulls were collected in eighteen farms. Serum samples were submitted to virus neutralization (VN) assay, while semen samples were used to detect BoHV-1 and BoHV-5 DNA by PCR. VN results showed that BoHV-1/5 antibodies were detected in bulls of 66.7% (12/18) of the farms, 295 (79.5%) BoHV positive bulls, 287 for BoHV-1 and 234 for BoHV-; at 43 vaccinated bulls 72.1% (31/43) showing serology negative. BoHV-1/5 DNA was detected in the semen of three bulls; one of the them presenting BoHV-1, one out three presenting BoHV-5 and one BoHV-1/5.co-infection All BoHV DNA positive samples came from animals presenting posthitis and other genital lesions at sampling. Results showed a high seroprevalence of BoHV-1/5 antibodies in bulls as well as strong evidence that these viruses are actively circulating in the cattle farms. A remarkable finding is that in the presence of clinically evident lesions in the genital tract, both BoHV-1 and 5 may found in semen.

摘要 牛α疱疹病毒1型和5型（BoHV-1/5）是引发牛呼吸道、生殖系统及神经系统疾病的主要病原体。本研究旨在调查来自南里奥格兰德州（RS）肉牛场的公牛血清样本中抗BoHV-1/5的中和抗体阳性率，并检测其精液中的病毒DNA。研究共从18个肉牛场采集了372份公牛血清与精液样本。血清样本采用病毒中和（VN）试验进行检测，精液样本则通过聚合酶链式反应（PCR）检测BoHV-1和BoHV-5的DNA。病毒中和试验结果显示，66.7%（12/18）的被检场公牛中检出了BoHV-1/5抗体；共295头（79.5%）公牛呈BoHV阳性，其中287头为BoHV-1阳性，234头为BoHV-5阳性。在43头已接种疫苗的公牛中，72.1%（31/43）的血清学检测结果为阴性。本研究在3头公牛的精液中检出了BoHV-1/5 DNA：1头为BoHV-1单一感染，1头为BoHV-5单一感染，剩余1头为BoHV-1/5共感染。所有BoHV DNA阳性样本均来自采样时表现出包皮炎及其他生殖器病变的受试动物。本研究结果表明，公牛体内BoHV-1/5抗体的血清阳性率较高，且有强有力的证据显示这些病毒在当地肉牛场中正处于活跃传播状态。一项值得关注的发现是，当受试公牛生殖道出现临床可见病变时，其精液中可同时检出BoHV-1和BoHV-5。