Caracterização clinicopatológica da mamilite aguda em ovelhas lactantes infectadas experimentalmente com o herpesvírus bovino 2

Diphenyl diselenide and cidofovir present anti-viral activity against Bovine Alphaherpesvirus 2 in vitro and in a sheep model

Bovine alphaherpesvirus 2 (BoHV-2) - the agent of bovine herpetic mamillitis (BHM) - is related to Human alphaherpesviruses 1 and 2 (HHV-1, HHV-2) and, as such, has been proposed as a model for vaccine and drug testing. We herein investigated the anti-viral activity in vitro against BoHV-2 of three anti-herpetic drugs: Cidofovir (CDV), Fanciclovir (FAM), Foscarnet (PFA), and diphenyl disselenide (Ph₂Se₂)_, a compound that has showed activity against HHV-2. Plaque reduction assays (PRA) revealed a significant reduction in viral plaques (p < 0.05) in cells treated with Ph₂Se₂ (79.7% reduction) or CDV (62.8%). FAM treatment resulted in a slight decrease in plaque number (22.9%, p < 0.05); PFA showed no activity. The effects of Ph₂Se₂ and CDV, alone or in combination, were investigated in ewes inoculated with BoHV-2 transdermally and submitted to daily topic treatment. Virus inoculated ewes developed lesions progressing through the stages of hyperemia, large papules or depressed dark areas, followed by scab formation. Treatment with Ph₂Se₂ resulted in reduction in clinical score from day 10 pi onwards (P < 0.05), shortening of clinical course and reduction in duration of virus shedding (P < 0.05) compared to untreated controls. Combined treatment (Ph₂Se₂ + CDV) and CDV alone, also led to clinical improvement (P < 0.05), yet less pronounced and delayed. These results are promising towards the use of Ph₂Se₂, alone or in combination with anti-herpetic drugs, in the treatment of udder and teat lesions produced by BoHV-2 in dairy cows.

A molecular survey using a validated real-time PCR assay finds no evidence of bovine alphaherpesvirus 2 in samples from animals with suspected vesicular disease in Brazil between 2014 and 2017

Bovine alphaherpesvirus 2 (BoHV-2) is the etiologic agent of bovine mammillitis (BM) and pseudo-lumpy skin disease. BM is also important because its clinical presentation can be confused with foot-and-mouth disease (FMD), making it necessary to establish differential diagnoses and perform additional laboratory tests. The objective of this work was to use a validated real-time PCR assay to test for the presence of BoHV-2 in samples from cattle and buffalo with suspected vesicular disease in Brazil. The method could detect the virus at a concentration of 0.5 fg/μL and had 99.4% amplification efficiency, a repeatability error of only 4.1%, and good reproducibility with other reagents. No evidence of BoHV-2 causing vesicular disease in cattle and buffalo was found in this work. This study was able to validate a new methodology for detection of BoHV-2 and evaluate its usefulness for investigating outbreaks of vesicular disease Brazil. The importance of BoHV-2 in cases involving other clinical signs should still be studied using the qPCR developed in this work.

Clinical, hematological and biochemical parameters of dairy cows experimentally infected with Vaccinia virus

Vaccinia virus (VACV) is the etiological agent of bovine vaccinia (BV), an important zoonosis that affects dairy cattle. There are many aspects of the disease that remain unknown, and aiming to answer some of these questions, the clinical, hematological, and biochemical parameters of VACV experimentally infected cows were evaluated. In the first part of the study, lactating cows were infected with VACV-GP2 strain. In the second part, animals previously infected with VACV-GP2 were divided into two treatment groups: Group 1, immunosuppressed cows; and Group 2, re-infected cows. In this study, BV could be experimentally reproduced, with similar lesions as observed in natural infections. Moreover, a short incubation period and local lymphadenopathy were also observed. VACV could be detected by PCR and isolated from scabs taken from teat lesions of all inoculated and re-inoculated animals. Lymphocytosis and neutrophilia were observed in all animals from the first part of the experiment, and lymphopenia and relative neutrophilia were observed in the immunosuppressed animals. Detection of viral DNA in oral mucosa lesions suggests that viral reactivation might occur in immunosuppressed animals. Moreover, clinical disease with teat lesions may occur in previously VACV-infected cows under the experimental conditions of the present study.

Acute and latent infection by bovine herpesvirus type 2 in a guinea pig model

Bovine herpetic mammillits is a self-limiting cutaneous disease of the udder and teats of cows associated with bovine herpesvirus 2 (BoHV-2) whose pathogenesis is poorly understood. This article describes the use of guinea pigs (Cavia porcellus) to study the pathogenesis of BoHV-2 infection. Twelve weanling female guinea pigs inoculated subcutaneously with BoHV-2 in the genitalia and teats developed local hyperemia, edema, vesicles, ulcers and scabs. Infectious virus was recovered between days 3 and 7 post-infection (pi) from the genital area (9/12) and teats (1/12); and all inoculated animals seroconverted (virus-neutralizing titers of 16-128). Histological examination of lesions revealed lymphoplasmacytic perivascular infiltrates and intranuclear inclusion bodies in keratinocytes. PCR examination of tissues collected at day 35 pi detected latent viral DNA predominantly in lumbosacral spinal segments. In another experiment, eight females inoculated with BoHV-2 in the genitalia and treated with dexamethasone (Dx) at day 35 pi developed mild to moderate local signs, yet no virus could be recovered from lesions. PCR examination of spinal segments from these animals confirmed the presence of latent viral DNA. These results demonstrate that guinea pigs are susceptible to BoHV-2 infection and therefore may be used to study selected aspects of BoHV-2 biology.

Distribution of latent bovine herpesvirus 2 DNA in tissues of experimentally infected sheep

The biology of latent infection by bovine herpesvirus 2 (BoHV-2), the agent of mammillitis in cows, remains largely unknown. We herein report attempts to reactivate the latent infection and investigated the sites of BoHV-2 latency in experimentally infected sheep. Ewes inoculated with BoHV-2 in the udder's skin shed virus for up to five days, developed mammillitis and seroconverted. However, attempts to reactivate latent infection by dexamethasone administration at day 40 pi failed. Nevertheless, viral DNA--and not infectious virus--was detected by PCR in several nerve ganglia and/or regional lymph nodes (LNs) of all animals at day 40 post-reactivation. Likewise, lambs previously inoculated with BoHV-2 in the nose harbored latent viral DNA in trigeminal ganglia, tonsils and regional LNs. These results demonstrate that BoHV-2 establishes latent infection in nerve ganglia and in regional lymphoid tissues, yet virus reactivation is not easily achieved by standard protocols used.