PERSISTENT INFECTION OF HUMAN CONJUNCTIVA CELL CULTURES BY MYXOVIRUS PARAINFLUENZA 3

Abstract

A human conjunctiva cell line persistently infected with the SF-4 strain of Myxovirus parainfluenza 3 (PIV-3) was studied.Normal cultures inoculated at a multiplicity of infection of 10 exhibited no cytopathic changes provided the cultures were kept in growth medium, while the use of maintenance medium did result in culture destruction. Since neither antibodies nor inhibitors were demonstrable in the growth medium, it was concluded that the maintenance of the carrier state was dependent, at least in part, on active cell growth and metabolism.During 76 subpassages, fluorescent antibody (FA), hemadsorption, inclusion staining, and cell-cloning procedures indicated infection of 61 to 97% of the cells.The carrier exhibited moderate resistance to superinfection with polio virus and ECHO 6 virus, but showed no resistance to vesicular stomatitis virus, Herpesvirus hominis, or Guaroa virus. Interferon was not demonstrated.Subpassage of a carrier culture for 5 months in antibody-containing growth medium produced a gradual decrease in the proportion of infected cells, although a "cure" was not effected. This gradual decrease of infected cells suggested an intracellular transfer of the virus during mitosis which was confirmed by FA and cloning procedures.