High temperatures for extended periods, which do not allow animals to recover from heat stress, affect in particular those BLV-infected animals that carry a high proviral load. For this study, animals were discriminated between BLV (+) and BLV (-), and those belonging to the first group, were classified based on their proviral load. The expression of the inflammatory cytokine TNF-α and its receptors, which play an important role in disease progression, were quantified by qPCR in two different seasons. During the summer, average temperature was 19.8 °C, maximums higher than 30 °C were frequent. Instead, during the autumn, the average temperature was 12.63 °C, and temperatures never exceeded 27 °C. During this season, almost no periods of temperatures exceeded the comfort limit. Our results revealed that the expression levels of TNF-α and its receptors were downregulated in animals with high proviral load. This fact could affect their antiviral response and predispose to viral dissemination; over time, animals with a poorer immune system are prone to acquiring opportunistic diseases. Conversely, animals with LPL maintained their expression profile, with behavior comparable to non-infected animals. These findings should be considered by producers and researchers, given the problems that global warming is causing lately to the planet.
Keywords: BLV; Heat stress; Immune system; TNF-Alpha; TNF-Alpha receptors.
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