Heterologous interference between Mayaro and Chikungunya viruses in Vero cells

Mayaro virus (MAYV) and Chikungunya virus (CHIKV) are arthritogenic alphaviruses with distinct natural vectors but common vertebrate hosts, whose concomitant circulation in Central and South America provides opportunities for mixed infections in humans. In view of this, we aimed to investigate the heterologous interference between these arboviruses during coinfections and superinfections in a primate cell line. Experimental infections with MAYV and CHIKV were performed singly, simultaneously or consecutively, and cytopathic effect, cell viability and virus load were assessed by phase contrast light microscopy, fluorimetry and reverse transcription-quantitative polymerase chain reaction, respectively. All infection schemes led to a strong cytopathic effect accompanied by an average reduction of almost 90 % in cell viability within 24 h post-infection. Although there was no statistically significant difference between the loads of both viruses in coinfections, a decrease in the individual virus load of more than 90 % when compared to their respective single infections was observed. Furthermore, superinfections resulted in widely significant differences in the amount of progeny formed for each virus, with a first-mover advantage regardless of the species. MAYV and CHIKV are subject to heterologous interference during coinfections and superinfections in primate cells, which could possibly impact disease outcome in humans.