Bovine respiratory syncytial virus (BRSV) is a major respiratory pathogen in cattle and is relevant to the livestock industry worldwide. BRSV is most severe in young calves and is often associated with stressful management events. The disease is responsible for economic losses due to lower productivity, morbidity, mortality, and prevention and treatment costs. As members of the same genus, bovine and human RSV share a high degree of homology and are similar in terms of their genomes, transmission, clinical signs, and epidemiology. This overlap presents an opportunity for One Health approaches and translational studies, with dual benefits; however, there is still a relative lack of studies focused on BRSV, and the continued search for improved prophylaxis highlights the need for a deeper understanding of its immunological features. BRSV employs different host-immunity-escaping mechanisms that interfere with effective long-term memory responses to current vaccines and natural infections. This review presents an updated description of BRSV’s immunity processes, such as the PRRs and signaling pathways involved in BRSV infection, aspects of its pathogeny, and the evading mechanisms developed by the virus to thwart the immune response.

Viruses are responsible for several diseases in animals and have also been linked to the drastic decrease in the number of bee hives worldwide. Considering the necessity to diagnose honey bee viruses, we developed and standardized two multiplex RT-PCRs. We evaluated the presence of six viruses described in Africanized Apis mellifera bees: Deformed wing virus (DWV), Sacbrood bee virus (SBV), Acute bee paralysis virus (ABPV), Israeli acute paralysis virus (IAPV), Black queen cell virus (BQCV), and Chronic bee paralysis virus (CBPV). Therefore, 164 samples of honey bees were collected in 27 apiaries of 12 municipalities in the states of Rio Grande do Sul and Santa Catarina, in southern Brazil. Among the 12 municipalities evaluated, five presented positive samples for BQCV, ABPV and DWV. Cases of co-infection by ABPV and BQCV and BQCV and DWV were observed in both states. In all apiaries with positive samples for viruses, Varroa destructor mite was reported or found. These results demonstrate the high occurrence of BQCV (36%) and the presence of ABPV (3%) and DWV (1%) in apiaries in Rio Grande do Sul, as well as in an apiary in Santa Catarina (75% BQCV and 12% DWV). The results confirm the circulation of these viruses in adult Africanized honey bees in southern Brazil, a factor that may be involved with the decline in the number of honey bees in this region of the country.

The search for natural resources with antiviral potential, as an alternative to synthetic drugs, has been growing and, in this sense, oregano presents itself as a potential candidate. However, the antiviral studies with oregano are still poorly explored. BoHV-1 stands out among veterinary pathogens, for its economic impact on cattle production. In this study, the antiviral and virucidal activity of polar extracts of Origanum vulgare was evaluated against BoHV-1. Infusion (INF10), decoction (DEC), and hydroalcoholic (HAE) extracts were tested to cytotoxic and antiviral assays on MDBK cells. Cytotoxic effects were analyzed through MTT assay and the antiviral activity was expressed as a percentage of inhibition (PI). BoHV-1 was incubated with O. vulgare extracts as virucidal assay. Concentrations ≤3.12 mg/ml (INF10) and ≤1.56 mg/ml (DEC/HAE) preserved the cell viability above 60%, and all extracts were safe (>96%) between 0.78 and 0.39 mg/ml. Regarding the antiviral activity, pre-treatment of all extracts highlighted in comparison to the post-treatment. The pre-treatment of infusion at 2 mg/ml highlighted due to the high cell viability (84.69%) and the elimination of the viral load. All extracts inactivated BoHV-1 from 2 hours of incubation (20 mg/ml), showing virucidal activity. These findings may be related to 4-hydroxybenzoic acid as prevalent in all extracts. These findings showed the in vitro antiviral and virucidal activity of oregano polar extracts against BoHV-1 and may be promising for the therapeutic use against herpesviruses infections.

In this study, the toxic effects of melittin on Madin-Darby Bovine Kidney cells (MDBK) were analyzed with respect to mitochondrial functionality by reduction of MTT and flow cytometry, apoptosis potential, necrosis, oxygen reactive species (ROS) production, lipid peroxidation, and DNA fragmentation using flow cytometry and cell membrane destabilization by confocal microscopy. The toxicity presented dose-dependent characteristics and mitochondrial activity was inhibited by up to 78.24 ±3.59% (P<0.01, n = 6) in MDBK cells exposed to melittin (10μg/mL). Flow cytometry analysis revealed that melittin at 2μg/mL had the highest necrosis rate (P<0.05) for the cells. The lipoperoxidation of the membranes was also higher at 2μg/mL of melittin (P<0.05), which was further confirmed by the microphotographs obtained by confocal microscopy. The highest ROS production occurred when the cells were exposed to 2.5μg/mL melittin (P<0.05), and this concentration also increased DNA fragmentation (P<0.05). There was a significative and positive correlation between the lipoperoxidation of membranes with ROS (R=0.4158), mitochondrial functionality (R=0.4149), and apoptosis (R=0.4978). Thus, the oxidative stress generated by melittin culminates in the elevation of intracellular ROS that initiates a cascade of toxic events in MDBK cells.

O sistema imune presente nas mucosas representa a barreira inicial frente à infecção por diversos patógenos que utilizam estas superfícies como porta de entrada no organismo hospedeiro, como é o caso dos Alphaherpesvirus bovino 1 (BoHV-1) e Alphaherpesvirus bovino 5 (BoHV-5). Estes vírus infectam os sistemas reprodutivo e respiratório de bovinos e são responsáveis por casos de Rinotraqueíte Infecciosa Bovina, Vulvovaginite Pustular Infecciosa e Balanopostite Pustular Infecciosa, assim como Meningoencefalite Herpética Bovina, respectivamente. A infecção pelos BoHVs ocorre nas cavidades revestidas por células epiteliais de mucosa, principalmente nasal e genital, sendo o ponto inicial de replicação, seguindo-se a disseminação local, viremia eventual e disseminação neuronal, até o estabelecimento da latência. A cooperação dos mecanismos de defesa confere proteção através do sistema integrado de mucosas por meio da ativação dos sítios efetores e especialmente produção de diferentes isotipos de imunoglobulinas, como a SIgA, realiza neutralização nas superfícies mucosas, e a IgG, que desempenha neutralização na mucosa e sistemicamente. A indução da imunidade nas superfícies mucosas através do uso de vacinas torna-se de extrema importância para a prevenção da adsorção do vírus à célula e infecção pelos microrganismos patogênicos e depende, especialmente, do imunógeno, via de imunização e substância adjuvante empregada nas formulações. Esta revisão teve como objetivo abordar os principais aspectos relacionados à infecção pelo BoHV-1 e BoHV-5, assim como os tipos de resposta relacionadas ao sistema imune de mucosas frente a estes vírus e, ainda, estudos relacionados à utilização das vias mucosas para administração de vacinas em diferentes espécies animais.

As superfícies mucosas representam uma importante porta de entrada para microrganismos que podem ser prejudiciais à saúde. A resposta imune humoral tem uma importante ação na defesa dessas superfícies, pois é capaz de prevenir a entrada de patógenos no organismo. Vacinas com aplicação local têm sido utilizadas com o objetivo de estimular uma resposta imune eficiente nas mucosas, uma vez que as vacinas convencionais, para aplicação parenteral, tendem a estimular uma resposta predominantemente sistêmica. Vacinas que utilizam a mucosa como via de inoculação são capazes de gerar uma resposta imune diretamente na mucosa de aplicação e mucosa correspondente, uma vez que o sistema mucoso é integrado, o que representa uma vantagem importante na escolha da via de inoculação. Este artigo tem como objetivo ilustrar alguns conceitos relacionados à imunidade mucosa em geral, bem como reunir informações sobre o que tem sido estudado em relação às vias de administração de vacinas nas mucosas, imunomoduladores e sistemas de liberação de antígenos.