INFECTION OF MCH CHINESE HAMSTER CELLS WITH HERPES SIMPLEX VIRUS: RELATION OF CELL KILLING TO TIME OF DIVISION

Persistent Herpes Simplex Virus Infection In Vitro with Cycles of Cell Destruction and Regrowth

Hampar, Berge (National Institute of Dental Research, Bethesda, Md.), and Mary Lou Copeland. Persistent herpes simplex virus infection in vitro with cycles of cell destruction and regrowth. J. Bacteriol. 90:205-212. 1965.-The susceptibility of two Chinese hamster cell lines to herpes simplex virus (HSV) was studied from the time of their initiation through successive subcultures. The cells' susceptibility to the cytocidal effects of HSV decreased as the number of cell passages increased. During the early cell passages, the decrease in cell susceptibility to HSV was characterized by an increased time after infection for complete cell destruction to occur, with a concomitant increase in the period when virus could be recovered from supernatant fluids. This was followed by a number of cell passages during which persistent HSV infections were established. The persistent infections were characterized by (i) cycles of virus synthesis and cell destruction followed by regrowth of the cells, (ii) initiation and maintenance under conditions optimal for cell growth in the absence of antibody, (iii) the cells' ability to be passaged while still maintaining their cycling patterns, (iv) a relationship between virus synthesis and cell proliferation, and (v) inability of long-term treatment with antibody to "cure" the persistent infections. The unique characteristics of this HSV infection were compared with other persistent in vitro viral infections.

Persistent cyclic herpes simplex virus infection in vitro. 3. Asynchrony in the progression of infection and cell regrowth

Hampar, Berge (National Institute of Dental Research, Bethesda, Md.). Persistent cyclic herpes simplex virus infection in vitro. III. Asynchrony in the progression of infection and cell regrowth. J. Bacteriol. 91:1965-1970. 1966.-The progression of virus-induced cytopathic effects (CPE) and virus synthesis was studied in localized areas of Chinese hamster cell cultures persistently infected with herpes simplex virus (HSV). CPE was initially evidenced by the presence of small multinucleated giant cells, followed by expanding plaquelike lesions with an occasional uninfected cell remaining within the infected areas. Cell detachment rapidly followed the appearance of viral antigen in infected cells. The surviving cells which proliferated to re-establish the cell sheet arose from two sources. The first was from viable cells which remained attached after expansion of localized areas of CPE, and the second was from reattachment of viable cells in the medium. CPE in localized areas was initiated at various times during the cycle irrespective of the virus titer in the medium. Cell regrowth in some areas and CPE in other areas occurred simultaneously throughout the cycle in an asynchronous fashion. Consequently, during periods of rising virus titers, most areas showed CPE while few areas displayed cell regrowth. As the virus titers declined, more areas showed cell regrowth and fewer areas displayed new cycles of CPE. CPE in localized areas was not initiated until cell regrowth had occurred. It is proposed that the proliferating cells were temporarily resistant to HSV infection, and that this resistance was ultimately lost in their progeny cells.