Interspecies interactions of arboviruses. I. Competition phenomenon in mixed populations of Japanese encephalitis and West Nile viruses.

Two phenomena, competition and independent reproduction, were observed on co-cultivation of Japanese encephalitis (JE) and West Nile (WN) viruses in permissive systems. Competition occurred in populations propagated in mouse brains and led to elimination of JE virus. Only clones of WN virus were isolated from these populations at the 1st-3rd passage level. No competition was observed in mixed infection of primary Syrian hamster kidney (SHK) cell culturess the population had the combined immunological phenotype JE+WN+, and contained discrete JE and WN virus clones and clones with duplex antigenic markers. Upon subcloning, the latter dissociated into JE and WN viruses. The competition phenomenon depended upon 3 factors: co-cultivation system, peculiarities of the virus strains, and virus dose. The capacity of WN virus strains to eliminate JE virus in mixed infection of mice varied.