Suppression of NK cell-mediated cytotoxicity and immunoenhancement of CD40 ligand against porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important pathogenics affecting swine industry worldwide. PRRSV is a single-stranded and positive sense RNA virus that belongs to the family of the Arteriviridae (genus Arterivirus). PRRSV has a restricted host and cell tropism, with porcine alveolar macrophages (PAMs) as important host cells. In 2006, most swine farms in China experienced a “high fever disease of swine” caused by new PRRSV variants, which led to great economic losses to Chinese swine industry, bring new challenge to the prevention and control of the disease. PRRSV is able to persist in pigs for several weeks to several months after initial infection. It appears to use several evasion strategies to circumvent both innate and adaptive immunity and the currently registered vaccines can not provide good protective efficiency in practice. Global efforts are made to better understanding host's immune response to PRRSV infection and develop better PRRSV vaccines