Resumen El alfaherpesvirus equino 1 (EHV-1) produce enfermedad respiratoria, abortos, muerte perinatal y desórdenes neurológicos en miembros de la familia Equidae. Las glicoproteínas de la envoltura viral son los antígenos inmunodominantes que generan respuesta inmune en animales infectados. La infección natural y las vacunas disponibles proporcionan protección parcial y de corta duración contra la reinfección. En este trabajo se expresó la glicoproteína C viral utilizando un baculovirus recombinante y se analizó la capacidad de inducir inmunidad protectora en ratones BALB/c al ser desafiados con el virus. Se evaluaron diferentes rutas de administración y distintos adyuvantes. La glicoproteína C indujo una respuesta IgG específica en suero; sin embargo, no logró evitar la entrada del virus al pulmón ni la aparición de signos clínicos, los cuales fueron variables entre los diferentes grupos de ratones. En todos los grupos inmunizados se retrasó la entrada del virus al pulmón y, cuando se utilizaron adyuvantes, el título viral fue significativamente menor que en el grupo control, así como en el grupo inmunizado por vía intranasal. Se concluye que la glicoproteína C producida indujo protección parcial frente al desafío viral según el adyuvante y la vía de inmunización.

Abstract Equid alphaherpesvirus 1 (EHV-1) causes respiratory disease, abortions, perinatal death and neurological disorders in horses. Envelope glycoproteins are the most immunodominant antigens in infected animals. Natural infection and available vaccines provide partial and short-term protection against reinfection. In this study, EHV-1 glycoprotein C was expressed with a recombinant baculovirus and the ability to induce protective immunity in BALB/c mice challenged with the virus was analyzed. Different routes of administration and adjuvants were evaluated. Glycoprotein C induced a specific IgG response in serum. However, it failed to prevent entry of the virus into the lung or the appearance of clinical signs, which were variable among different treatment groups. Entry of the virus into the lung was delayed in all immunized groups. The viral titer was significantly lower when adjuvants were used, as well as in the intranasally immunized groups compared to the control group. Therefore, glycoprotein C induced partial protection against the challenge with the virus, depending on the adjuvant and the route of immunization.

ABSTRACT: Equine herpesvirus type 1 (EHV-1) is an important pathogen that causes abortion, neonatal disease, respiratory disorders, and neurological syndrome in equine populations worldwide. To evaluate EHV-1 as a cause of abortion and perinatal mortality in Brazil, tissue samples from 105 aborted equine fetuses, stillbirths, and foals up to one month of age were examined using virus isolation, immunohistochemistry (IHC), histopathology, and nested polymerase chain reaction (PCR). Two fetuses were positive for EHV-1 by PCR, one of which showed syncytia and eosinophilic intranuclear inclusion bodies in bronchial epithelia, but it was negative by virus isolation. The other showed no characteristic histological lesions, but it was positive by viral isolation. No sample was positive by IHC. The results presented low occurrence of EHV-1 in the studied population and suggested that the use of a combination of techniques increases the likelihood of an accurate diagnosis of EHV-1.

RESUMO: O herpes-vírus equino tipo 1 (HVE-1) é um importante agente patogênico causador de aborto, doença neonatal, distúrbios respiratórios e síndrome neurológica em populações de equinos em todo o mundo. Para avaliar a ocorrência do HVE-1 como agente causal de abortamento e mortalidade perinatal no Brasil, foram examinadas amostras de 105 fetos equinos abortados, natimortos e potros de até 1 mês de idade, utilizando as técnicas de isolamento viral, imuno-histoquímica (IHQ), histopatologia e reação em cadeia da polimerase aninhada (nested-PCR). Dois fetos foram positivos na análise de PCR, e um deles apresentou corpúsculos de inclusão viral eosinofílicos e sincícios no epitélio brônquico, porém foi negativo na análise de isolamento viral. O outro feto não apresentou lesões histológicas características de infecção herpética, mas foi positivo na análise de isolamento viral. Nenhuma amostra apresentou resultado positivo pela análise de IHQ. Os resultados demonstraram baixa ocorrência de HVE-1 na população estudada e que o uso de diferentes técnicas diagnósticas aumenta a probabilidade de um diagnóstico preciso para o HVE-1.