Trachoma Viruses Isolated in the United States 2. Assay of Egg Infectivity and Stability

Abstract

Except for the seasonal insusceptibility of eggs during the late summer or fall, reliable and reproducible infectivity assays were performed on three representative strains of trachoma virus isolated in the United States. In general the linear inverse relationship between amount of virus and time of death applied to these trachoma viruses, as to other members of the psittacosis-LGV group. One strain (ASGH) tended to kill eggs 1 day earlier than another strain (BOUR) at all inoculum levels. The strains were ether labile and rapidly lost infectivity at 37 C or above, but were fairly stable at - 40 C for several months, or when lyophilized. Sodium desoxycholate interfered far more with staining properties of the virus than with infectivity.