Experimental research on co-infection of rabies virus and canine distemper virus in Vero cells

Objective To investigate the co-infection of rabies virus(RV)and canine distemper virus(CDV)in Vero cells and the influence of virus titer caused by co-infection,compare the sensitivity of different virus detection methods.Methods After the RV and CDV which was cultured alone and coinfected in Vero cells were diluted,the virus was inoculated Vero cells and cultured under 37 ℃ 5%CO2 atmosphere.After 5 d,the virus titer was detected by direct immunofluorescent assay(DFA),RT-PCR and real-time RT-PCR,the sensitivity of three virus detecion methods were also compared.Results The RV and CDV could infect and proliferate in Vero cells at the same time,TCID50 of CDV cultured alone was 10-5.8/0.05 ml,TCID50 of co-infection was 10-5.5/0.05 ml.The maximum dilution of positive infection detected by DFA,RT-PCR and real-time RT-PCR was 10-6,10-5 and 10-6.Conclusion Co-infection had little influence on virus titer.The sensibility of DFA,RT-PCR and real-time RT-PCR was equivalent.The virus titer detection of mixed vaccine including RV and CDV could be tested by DFA after the mixed vaccine was inoculated in Vero cells directly without neutralization of one virus.