RESUMO
O presente estudo teve como objetivo determinar a prevalência de anticorpos contra os vírus da influenza (EIV), da arterite viral (EVAV) e herpesvírus (EHV) em eqüinos no Estado do Rio Grande do Sul (RS),
Palavras-chave: soroprevalência, epidemiologia, EIV, EVAV, EHV.
ABSTRACT
This study was aimed at investigating the prevalence of antibodies against, influenza virus (EIV), equine viral arteritis virus (EVAV), and herpesvirus (EHV) among horses in Rio Grande do Sul (RS) state, Brazil. Serum samples from horses of 65 counties of northern and northwestern RS, were tested by inhibition hemaglutination test (HI) for EIV and by virusneutralization test (VN) for EVAV and EHV antibodies. From 1506 samples, 986 (65.4%) had antibodies to EIV (titers ranging from 10 to 1280), 33 (2.2%) were positive to EVAV . Among the 65 counties, 55 (84.6%) presented at least one positive animal to EIV, 15 (23%) to EVAV, and 12 (18.5%)
RESUMO.-A mamilite causada pelo herpesvírus bovino tipo 2 (BoHV-2) possui importante repercussão sanitária em gado leiteiro de alguns países, mas a sua patogenia permanece pouco conhecida. Este trabalho descreve a reprodução e caracterização da mamilite aguda em ovelhas lactantes inoculadas com o BoHV-2 na pele do úbe-re e dos tetos. is an important disease in dairy herds yet its pathogenesis remains largely unknown. This report describes the reproduction and characterization of acute mammillitis in lactating ewes inoculated with BoHV-2 in the skin of the udder and teats. Five out of eight inoculated ewes developed large plaques, with focal necrosis, small vesicles and crust formation in the inoculated areas. The lesions were first observed on day 4 post-inoculation (pi), progressed in size and severity up to days 7-8pi and subsided progressively thereafter. Infectious virus was isolated from the lesions at days 7 and 8pi. Viral antigens and herpesvirus-like particles were demonstrated by electron microscopy in lesions examined at days 5, 6 and 10pi. Histological findings included epithelial necrosis, erosions and ulcers, and formation of syncytial cells. Intranuclear inclusions bodies in epithelial, syncytial and inflammatory cells and lymphoplasmacytic inflammatory infiltrate in the dermis were also observed. In a second experiment, seven out of ten lambs inoculated into the nostrils and muzzle developed nasal hyperemia and discharge, vesicles, and erosions in the nose. Infectious virus was isolated from lesions during up to three days and all lambs seroconverted to BoHV-2. Attempts to reactivate the latent infection by dexamethasone administration on day 40pi failed, since virus shedding, clinical recrudescence or seroconversion were not observed. The reproduction of acute infection and mammillitis resembling that occurring in cattle paves the way for the use of sheep to study several aspects of the biology of BoHV-2 infection.
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