The Thai Journal of Veterinary Medicine


Bronchoalveolar cells collected by lung lavage 28 days post infection (DPI) of negative controls, Mycoplasma hyopneumoniae (M. hyo)-infected, Porcine Respiratory and Reproductive Syndrome virus (PRRSV)-infected and dual-infected pigs, were evaluated for various cytokine mRNA (IL1α, IL1β, IL6, IL8, IL10, IL12, and TNFα). Semiquantitative RT-PCR revealed that IL1β, IL6, IL10 and the IL12 mRNA expression was significantly increased in dual-infected pigs, compared with the negative controls. PRRSV-infected pigs had significantly increased levels of IL10 and IL12 mRNA. The increased IL10 gene expression that was observed in the dual infected pigs may play a role in the potentiation of PRRSV-induced pneumonia by M. hyo. These results suggest that increased mRNA levels of proinflammatory cytokine gene expression may be related to the increased severity of clinical disease and pneumonia, especially in the dual infected pigs and that the reciprocal regulation of IL10 and IL12 genes may explain, in part, the prolonged observed persistence of PRRSV infection in pigs that are simultaneously infected with M. hyo.

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