EFFECT OF REDUCING AGENTS ON THE VIABILITY OF EQUINE ENCEPHALOMYELITIS VIRUS (EASTERN TYPE)

Abstract

The present communication deals with the effect of reducing agents (cysteine hydrochloride, sodium thioglycollate, and sodium formaldehyde sulphoxylate) on the viability of equine encephalomyelitis virus (Eastern type). Cysteine hydrochloride was found to be a valuable reagent in in vitro studies of equine encephalomyelitis virus, because it greatly retards loss of infectivity of the virus under experimental conditions. It was observed that a virus suspension containing cysteine hydrochloride (1:1000) remained infective after exposure to 37 °C. for 14 days, although the guinea-pig titre was reduced from 1:108 to 1:102. The same reduction in the titre of virus suspended in buffered 0.85% sodium chloride solution occurred after exposure to 37 °C. for 120 hr. only, and in unbuffered 0.85% sodium chloride after 24 hr. exposure. Further, equine encephalomyelitis virus, in the presence of cysteine hydrochloride, retains its infectivity without demonstrable loss, over a pH range between 4.8 and 8.2 for 48 hr. at 37 °C. The titre of equine encephalomyelitis virus is maintained at 37 °C. for 48 hr. in a rather wide range of Eh, created with the aid of cysteine hydrochloride, at least in the range between − 0.151 and + 0.02 volts. On the other hand, addition of sodium formaldehyde sulphoxylate or sodium thioglycollate to a suspension of equine encephalomyelitis virus does not retard loss of infectivity of the virus. These reagents, therefore, are not suitable for the conservation of infectivity of the virus in vitro.