Abstract
Congenital or neonatal infection of mice with lymphocytic choriomeningitis (LCM) virus results in a life-long virus carrier state (Traub, 1936; Hotchin, 1962). In a number of mouse strains, but not in all, this persistent infection may result in a slowly progressing disease. Generally the disease does not manifest itself before the animals are several months old (Hotchin, 1965). A chronic, non-cytopathogenic infection can also be established in mouse cells in vitro. After an initial high virus yield, infected cultures continuously produce virus at a variable but restricted rate, without impairment of cell growth (Lehmann-Grube, Slenczka & Tees, 1969).
The chronic virus carrier state of mice may result in altered susceptibility to infection with other viruses, e.g. eastern equine encephalomyelitis (Wagner & Snyder, 1962), Rauscher leukaemia virus (Young & Barski, 1966), polyoma virus (Hotchin, 1962); in other instances susceptibility may not be changed, e.g. yellow fever (Volkert, Larsen & Pfau, 1964) or ectromelia (Mims & Subrahmanyan, 1966).
* Supported by U.S.P.H.S. Training Grant No. GM 01248 from the National Institute of Medical Sciences (awarding unit).