Orthopoxvírus vaccínia na região norte do estado de Minas Gerais: avaliação da circulação e medidas para minimizar o seu impacto na economia leiteira da região

• Ano de defesa: 2024
• Autor(a) principal: Kamila Lorene Soares Rocha
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais
• Palavras-chave em Português: Microbiologia; Vaccinia virus; Infecções por Poxvinidae; Biologia Molecular; Sorologia; Queijo; Vírus vaccínia, ortopoxvírus, vaccínia bovina, biologia molecular, sorologia, queijo artesanal.
• Link de acesso: https://hdl.handle.net/1843/84940

ABSTRACT Vaccinia virus (VACV) belongs to the genus Orthopoxvirus and the Poxiviridae family. The Poxviridae family has a virus genetically and morphologically complex, able to infect a wide spectrum of domestic and wild hosts. VACV is the etiological agent of bovine vaccinia (VB), characterized as an occupational zoonosis. This zoonosis affects cattle, causing lesions commonly seen on teats and udders. Due to the location of the lesions, VACV mainly spreads during the milking process, whether manual or mechanical. Studies have sought to correlate environmental characteristics of dairy farms and management practices with the risk of exposure of dairy cows to VACV. The silent circulation virus in rural properties has been observed, even without the presence of clinical signs in animals. In addition, in humans, beyond the systemic symptoms, VACV causes vesicular-pustular lesions generally found on the hands and fingers. This infection usually happens after direct contact with infected dairy cattle, or through alternative routes of exposure such as contact with raw milk in cheese production and even consumption of these products. In this way, the objective of this study was to evaluate the circulation of VACV in the Serro region, considered one of the most important cheese producers in the state, and to provide support to rural producers regarding the flow of dairy production in the absence and presence of outbreaks. Furthermore, was evaluated the circulation of VACV in non-human primates in Minas Gerais state in northern region, aiming to map the virus circulation in this wild animals group. The first study part was accomplished on four rural properties in the Serro’s region, producers of artisanal cheese, one of which had a history of a VB outbreak previously. Semi-structured questionnaires were applied to verify possible factors that may favor exposure to VACV in the milk and artisanal cheese production. From this, research was carried out the investigation of the entire cheese chain, with subsequent monitoring of these stages, so that from then on, suggest methodological improvements during animal management through lectures and distribution of educational material to producers participating in the project. In this study, it was possible to observe a seroprevalence for OPXV of 71.42% in individuals not vaccinated for smallpox, demonstrating that in rural environments in endemic areas, individuals are exposed to VACV through alternative routes and not only through direct contact with infected cattle. In addition, in relation to the analyzes of cheese, milk and feces of cattle and horses carried out in the study, these presented negative results for the detection of VACV through the real-time PCR technique, thus demonstrating that, during the study, the rural Properties did not present the active circulation of VACV. Moreover, the visible lesions absence in cattle also corroborates these results. However, in all groups of domestic animals analyzed, high levels of positivity for anti-OPXV neutralizing antibodies were found, 80% in dogs, 97.89% in cattle and 100% in horses, indicating a previous silent circulation. Regarding the VACV circulation in non-human primates in the northern region of the state, 51 neotropical primates belonging to three species were evaluated in 11 counties. As a result, two animals belonging to the sampled group showed seropositivity for OPXV based on the PRNT technique, demonstrating previous exposure to the virus. In conclusion, by better understanding the VACV circulation as well as its possible infection routes, is target to minimize the VACV virus impact on the dairy economy in Serro region, through the knowledge dissemination about the virus, and good practices in the dairy flow production, from milking until the final product. In this way, it would be possible to reduce the risk of virus spreading through the raw milk and cheese consumption.