Amino Acids Requirements for Reproduction of Arboviruses 1

Abstract

Discussion and Summary

In the present experiments, it was shown that the maturation of CHIK and DEN-1 viruses was markedly suppressed by the deprivation of glutamine and cystine, respectively. The difference of amino acid requirements may reflect a difference in the maturation process of the two kinds of viruses. Evidence have been presented, indicating that the maturation sites of group A and B arboviruses were characteristically different from each other (11, 14).

Some details of the mechanism(s) of the phenomena were investigated, especially those dealing with CHIK virus and glutamine. The inhibitory effect of deprivation was reversible; the virus yields were restored by putting the cells from deprived medium into normal medium and vice versa. Such restoration and suppression were particularly clear during the earlier stages of the virus infection. In the radioisotope incorporation experiments, it was shown that the deprivation was not directly related to the viral RNA or protein synthesis in the infected cells. In the electron microscopic examinations, the cells infected with virus and cultured with deprived medium did not reveal the “core particles” inevitably seen in the same cultures fed with normal medium. This finding suggests that the deficiency influences the step(s) prior to the appearance of the core particles. This may be compatible with the above-mentioned data indicating that the reversibility of the deficiency effect was more clearly demonstrated during the earlier stages of the virus infection than in the later stages.

It can be postulated therefore that the amino acid deprivation (L-glutamine in the case of CHIK virus) is possibly involved at certain stages for the assembly of viral structures to produce complete virions. Since, however, it was clearly shown that the glutamine did not compensate the low ionic strength effect already described, the viral maturations stages affected by amino acid deficiency and low ionic strength are probably different from each other.