DNA of bovine herpesvirus type 1 in the trigeminal ganglia of latently infected calves.
ABSTRACT Twelve calves infected with bovine herpesvirus type 1 (BHV-1) were killed when in a latent state of infection. Latency was verified 30 days after virus inoculation of the calves by seroconversion, absence of virus shedding, and in 2 calves, by recrudescence of the infection after they were treated with dexamethasone. By in situ hybridization techniques and autoradiography, DNA of BHV-1 was detected in 13 of 23 trigeminal ganglia of latently infected calves. Viral DNA was restricted to the nucleus of nerve cells. Single neurons harboring BHV-1 DNA were observed in 4.9% of the sections (n = 325) of the trigeminal ganglia. The results obtained correspond to those known from herpes simplex virus infections in mice. The implications for the virus-host relationship are discussed.
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ABSTRACT: Epidemiological data describing bovine herpesvirus 1 (BoHV-1) infection in Brazilian cattle herds are scarce. A cross-sectional study was conducted in the state of Paraná between December 2001 and July 2002 with the objective of estimating the apparent prevalence of BoHV-1-seropositive herds and animals and identifying the potential risk factors for infection in farms with breeding animals in the state of Paraná in Southern Brazil. The state was divided into seven regions based on the livestock production dynamics of the different areas. Sampling was performed in two stages. Initially, herds were randomly selected, followed by a random selection of animals within the selected herds. Blood samples were collected from 14 803 females, aged ≥24 months, from 2018 BoHV-1 non-vaccinated herds. Serum samples were tested for antibodies against BoHV-1 using an indirect enzyme-linked immunosorbent assay (ELISA). The apparent prevalence of seropositivity in the herds and animals in Paraná was 71.3% (95% CI: 69.3-73.3) and 59.0% (95% CI: 56.2-61.8), respectively. Multiple logistic regression analysis revealed that risk factors associated with the presence of the infection were as follows: beef herds [OR = 1.58 (1.12-2.23)], natural service [OR = 1.48 (1.02-2.14)], purchase of animals [OR = 1.90 (1.52-2.37)], pasture rental [OR = 2.24 (1.51-3.33)], existence of calving pens [OR = 1.56 (1.20-2.03)] and records of abortion in the last 12 months [OR = 1.45 (1.08-1.95)]. These results indicate that BoHV-1 infection is widespread in the state of Paraná.Transboundary and Emerging Diseases 02/2012; · 2.10 Impact Factor
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ABSTRACT: Bovine herpervirus type 1 (BHV-1) is widespread in beef and dairy herds, causing great economic losses in cattle breeding. Infections caused by BHV-1 involving the respiratory, genital, reproductive and nervous systems can determine a wide variety of clinical manifestations wich are common on the other infectious and parasitic diseases. Several methodologies have been developed for laboratory diagnosis of BHV-1. Traditional serological techniques are unable to diferentiate animals exposed to the virus strains in the vaccine from those seropositives by natural exposure to the field strains. Thus the diagnosis can only be conclusive by detecting BHV-1 directly in clinical samples. Virus isolation has the disadvantage of requering viability in the viral particle, which in many situations may reduce the sensitivity and specificity of the technique. The immunoperoxidase and immunofluorescent techniques, although they do not require the infectiousness of the virus, can be seriously compromised if the structural integrity of the viral particle is not maintained. Currently the polymerase chain reaction assay is being universally adopted in the diagnosis of many virus, including BHV-1. This methodology has the advantage of not requiring the viral particle viability while providing high sensitivity and specificity and fast results. O herpesvírus bovino tipo 1 (BHV-1) encontra-se amplamente disseminado em rebanhos de corte e leite, determinando grandes prejuízos econômicos à exploração pecuária. A infecção pelo BHV-1 pode comprometer os tratos respiratório, genital, reprodutivo e nervoso e ocasionar uma ampla variedade de manifestações clínicas que são comuns a outras doenças infecto-parasitárias, inviabilizando o diagnóstico clínico conclusivo. Várias metodologias foram desenvolvidas para a realização do diagnóstico laboratorial do BHV-1. Contudo, as técnicas sorológicas tradicionais são incapazes de diferenciar a soroconversão originada pela infecção natural daquela devido à vacinação. Com isto, o diagnóstico conclusivo somente é possível pela identificação do BHV-1 diretamente em amostras clínicas. O isolamento viral em cultivo celular apresenta como desvantagem a necessidade da viabilidade da partícula viral, o que em muitas situações pode ocasionar uma redução na sensibilidade e especificidade da técnica. As técnicas de imunoperoxidase e imunofluorescência, apesar de não exigirem a infecciosidade do vírus, podem ser seriamente comprometidas caso a integridade estrutural da partícula não seja mantida. Atualmente a técnica da reação em cadeia pela polimerase está sendo universalmente adotada no diagnóstico de diversas viroses, inclusive do BHV-1. Esta metodologia apresenta como principais vantagens a não exigência da viabilidade da partícula viral, alta sensibilidade / especificidade e rapidez na obtenção dos resultados.Semina : Ciências Agrárias. 01/2009;
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ABSTRACT: Calves were vaccinated intranasally (IN) or intravenously (IV) with a thymidine kinase-negative (tk-) BHV-1 mutant. Vaccinated calves developed neutralizing antibodies but did not show clinical signs of infectious bovine rhinotracheitis (IBR). Vaccination also prevented clinical signs of IBR disease following IN challenge exposure of the calves to parental Los Angeles (LA) and USDA Cooper strains of tk+ BHV-1. Nasal swabs were collected for 10 days after the vaccination and the challenge exposures to monitor BHV-1 multiplication. At both 91 and 121 days post vaccination (PV), calves were also stressed for 5 days with dexamethasone (DEX) to induce reactivation of BHV-1 and nasal swabs were obtained. tk- BHV-1 multiplied in the nasal mucosa of IN vaccinated calves and was also recovered after DEX treatment. Likewise, tk- BHV-1 was isolated from the buffy coat fraction of IV vaccinated calves, but not from nasal swabs. tk- BHV-1 vaccination reduced the multiplication of tk+ BHV-1 in the nasal mucosa, but did not completely prevent development of a persistent infection by the challenge virus. The phenotypes of viruses isolated from the nasal swabs and buffy coats were analyzed by enzyme assays of extracts from virus-infected cells and by plaque autoradiography. These assays showed that tk- BHV-1 can persist for at least 3 months in vaccinated calves and may also be transmitted from vaccinated to control calves without reverting in vivo to tk+. The results demonstrate that the tk- BHV mutant is attenuated and efficacious as a vaccine.Archives of Virology 02/1985; 86(1-2):63-83. · 2.03 Impact Factor