Interferon-gamma and interleukin-4 expression during Fasciola gigantica primary infection in crossbred bovine calves as determined by real -time PCR.

Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) expression in crossbred (Bos taurusxBos indicus) bovine calves during primary infection with Fasciola gigantica was measured. Ten crossbred calves of 1-year age were divided into two groups of five calves each, group I uninfected control and group II calves orally infected with a dose of 1000 metacercariae of F. gigantica. The two cytokines were measured 10, 30 and 75 days post-infection (PI) by real-time polymerase chain reaction (RT-PCR) with the double stranded DNA-binding dye SYBR Green. IL-4 was present in detectable levels in peripheral blood mononuclear cells (PBMCs) of infected animals at 10, 30 and 75 days PI but no IFN-gamma was detected in PBMCs of infected animals at 10 and 30 days PI. However, at 75 days PI, IFN-gamma in two infected animals was present in detectable level. Eosinophil count increased from 2nd fortnight after infection and the increased level persisted till the termination of experiment. Present study indicated that T-cell response during F. gigantica infection was Th2-type during earlier phase of infection, which may be polarized in chronic infection to that of a Th0-type.