Mixed infection with simian virus 40 (SV40) and adenovirus 1 2 can occur in African green monkey kidney (AGMK) cells in vitro, and electron micrographs demonstrating both viruses within the nucleus of a single cell have been presented ( 1 ) . Variable degrees of partial exclusion were produced by altering the time interval between inoculation of SV40 and adenovirus 12, and approximately 40% of the cells contained both viruses when the adenovirus was inoculated 24 hours after SV40(1). Further studies of AGMK cultures infected with both viruses compared with cultures infected with adenovirus 12 only have shown that SV40 enhances the growth of the adenovirus. A similar enhancement of growth of adenovirus 5 has been found when AGMK cultures were infected with SV40 and adenovirus 5.Materials and methods. Cell Cultures: Primary AGMK cell cultures were obtained from Microbiological Associates, Inc., Bethesda, Md., and primary human embryo kidney cell cultures (HEK) from the Virology Research Resources Branch, National Cancer Institute, through the kindness of Drs. Robert E. Stevenson and Theodore Malinin. Roller tube cultures maintained in a medium composed of 2 % fetal bovine serum and 98% mixture 199 and incubated at 36.5"C were used in all experiments.Viruses: SV40 and adenovirus 12 strains were the same as those previously described (1). Adenovirus 5 was obtained from the American Type Culture Collection. SV40 was grown and titrated in AGMK cell cultures, and adenoviruses 12 and 5 were grown and titrated in HEK cultures. Viruses were titrated by serial 10-fold dilutions with 3 to 5 tubes per dilution. Titrations were observed for 2 1 days and titers were calculated by the Reed-Muench method.The amount of adenovirus in the AGMK cultures after infection with both SV40 and adenovirus 12 or adenovirus 5 was determined by titration in HEK cell cultures in which a typical adenovirus-type CPE was produced. Although Shein and Enders have shown that SV40 can produce an incomplete CPE in HEK cell cultures after more than 17 days (2), the cellular degeneration described by them did not resemble the CPE produced by adenovirus 12 and 5, and the inocula they used contained considerably more SV40 than could have been present in the terminal dilutions in our titrations.Experiments and results. In the first experiment, AGMK cell cultures infected with adenovirus 12 only were compared with similar cultures infected simultaneously with both SV40 and adenovirus 12 (Table I). After 48 hours' incubation, clusters of rounded refractile cells were observed in both the singly and doubly infected cultures although the changes were more extensive in the doubly infected cultures. Uninfected control cultures showed no changes. At 72 and 122 hours, the CPE had progressed in all infected tubes; however, it continued to be more severe and extensive in the doubly infected cultures.Electron microscopic studies at 72 and 122 hours showed a significant difference between the singly and doubly infected cultures. In the singly infected cultures, althou...

Bergey (1907) is generally credited with the fir'st isolation of Actinomyces from the normal human mouth. Since then there have been a few reports of the recovery from the normal oral cavity of organisms which appear to have been identical, or nearly so, with strains isolated from clinical actinomycosis (

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of green monkey kidney cells infected with adenovirus 12 and with adenovirus 12 plus simian virus 40. J. Bacteriol. 91:262-265. 1966.-Immunofluorescence studies of the viral antigens and tumor (T) antigens of adenovirus 12 and simian virus 40 (SV40) in green monkey kidney (GMK) cells infected with adenovirus 12 alone or in combination with the SV40 virus showed that the adenovirus 12 viral antigen was produced in detectable amounts only in the cells infected with both viruses. The adenovirus 12 T antigen, on the other hand, was formed in the GMK cells infected with the adenovirus 12 only. This antigen was formed as early as 18 hr after viral infection, and persisted for at least 48 hr after virus infection. There was a correlation between the appearance of the immunofluorescent T antigen in the nucleus and the electron microscope appearance of "nuclear stippling," which developed in the nuclei of GMK cells after infection with adenovirus 12 only, as well as after infection with both viruses.