IMMUNE RELATED GENES EXPRESSION ANALYSIS IN KOI FISH AFTER VACCINATED WITH KOI HERPES VIRUS DNA VACCINES

Abstract

Vaccination is a practical step in preventing diseases caused by koi herpes virus (KHV) in koi fish (Cyprinus carpio haematopterus). We have developed two DNA vaccines for KHV named as GP-25 and GP-11 from two local isolates coded as ORF25 and ORF81, respectively. Although both vaccines have been reported to increase survival rates, the evaluation of koi fish immune responses at the molecular level has not been done post-vaccinations. The aim of this research was to determine the effects of koi herpesvirus DNA vaccine on the immune-modulation of koi fish at mRNA level. This recent research used the best vaccine doses of both vaccines determined from our previous study: 7.5 and 12.5 µg per 100 g fish of GP-11, and 12.5 µg per 100 g fish of GP-25. The immune gene expression was analyzed using the RT-qPCR method from the fish liver at 0, 1, 7, 14, and 28 days post-vaccination (dpv). The results showed that, in the vaccinated fish, the immune genes viz. tumor necrosis factor a (TNFa), interleukin-1b (IL1b), interferon-g (IFNg), Mx1, immunoglobulin Mu chain (IgM), and major histocompatibility complex (MHC) class I and class II were induced to significant extents. The higher dose vaccination using the GP-11 vaccine showed higher immune gene expression than that of the lower dose. Furthermore, the GP-25 vaccine had induced lower immune responses than the GP-11 vaccine when using the same dose of vaccination, but relatively the same when the half-dose of GP-11 vaccine was used. In conclusion, the GP-11 and GP-25 vaccine provided the immune-modulatory effects on the koi fish immune response after vaccination.