Identification and amplification of Japanese encephalitis virus and Getah virus propagated from a single porcine serum sample: a case of coinfection

We detected two viruses, Japanese encephalitis virus (JEV)/Kochi/01/2005 and Getah virus (GETV)/Kochi/01/2005 in the same culture supernatant obtained by inoculation of Vero cells with a swine serum sample and subsequent passaging of the supernatant in Vero cells. Phylogenetic analysis using the nucleotide sequences of the complete genome and the E2 region of GETV indicated that GETV/Kochi/01/2005 is most similar to a Mongolian strain. In contrast, a partial sequence of the nsP1 protein coding region of GETV/Kochi/01/2005 showed that it was similar to Japanese strains isolated in the 1980s. Alignment of the nucleotide sequence of the E region of JEV showed that JEV/Kochi/01/2005 has the highest similarity to a Japanese strain. We also examined the changes in the amount of JEV/Kochi/01/2005 and GETV/Kochi/01/2005 present after passaging in Vero cells. The RNA copy number and infectious titer of JEV/Kochi/01/2005 decreased, whereas those of GETV/Kochi/01/2005 increased, following repeated passages in Vero cells. Our results provide evidence for coinfection with JEV and GETV in the Kochi/01/2005 pig. This is the first report of incidental confection with JEV and GETV in a domestic animal.