Effects of storage on eastern equine encephalitis virus.

Abstract

A 4-month study on the influence of certain factors upon eastern equine encephalitis virus in stored mosquitoes and brain tissue revealed the following: (1) Killing of EEE-infected mosquitoes by brief exposure to ether or chloroform fumes had no ill effects upon the virus they contained. (2) A constant temperature of −70°C or −20°C was found best for preserving EEE virus in intact, infected mosquitoes. Several hours at room temperature caused loss of viability of most of the virus present, as did fluctuations 2 to 5 times weekly from 0°C to −20°C. Fluctuations in temperature below the freezing point also caused some drop in virus titer. (3) Carbon dioxide gas in an open type dry ice chest had no apparent deleterious effect upon EEE virus in infected, intact mosquitoes, intact mouse brain tissue, or mosquito and mouse brain suspensions in distilled water, buffered saline, 0.1% bovine albumin, or 30% normal horse serum. (4) Distilled water was an unsuitable diluent for suspensions of EEE-infected mosquitoes. Buffered saline and 0.1% bovine albumin both gave better, but still rather poor results. Thirty per cent normal horse serum proved superior, since with it no drop in virus titer was observed. (5) All the above diluents gave satisfactory results in 10% EEE-infected mouse brain suspensions during the 4-month test period.