Virus In Human Cells Research Articles

Evidence for genetic recombination between endogenous and exogenous mouse RNA type C viruses.

Abstract Two viruses isolated following prolonged growth of serologically distinct mouse type C RNA viruses in human cells have previously been shown to have acquired common envelope properties distinct from those of either parental virus. Virus neutralization tests show that the viruses selected in human cells possess envelope antigens identical to those of endogenous mouse type C viruses of cells in which the parental viruses had been propagated. In contrast, the p12 polypeptide of each virus selected in human cells is antigenically indistinguishable from that of its respective parental virus and different from those of known endogenous mouse type C viruses. Molecular hybridization indicates significant differences in the genetic sequences of one virus and its parent, excluding the possibility that it arose from a point mutation. These findings indicate that the viruses selected in human cells represent genetic recombinants between exogenous and endogenous mouse type C viruses.

The formation and nature of foci induced by a modified sarcoma virus in human cells.

Murine sarcoma virus (MSV), which in its natural state is enveloped in a murine leukaemia virus coat, can, under select conditions of aggregation with feline leukaemia virus (FelLV), be made to infect and transform cat embryo cells (Fischinger & O'Connor, 1969). The product of such an infection is a new FelLV pseudotype of sarcoma-MSV (FelLV) which replicates to a high titre in cat cells, possesses a new host range, and is neutralized by FelLV antisera (Fischinger & O'Connor, 1969; Sibal et al. 1970). The infectious capacity of MSV (FelLV) is not limited to cat cells but is also manifest by a morphological transformation of cultured human, dog and pig cells (O'Connor & Fischinger, 1970; Chapman, Fischinger & O'Connor, 1970). The MSV infection of mouse cells is defective in the sense that both focus formation and progeny virus replication are only initiated by an infection of a cell with both MSV and murine leukaemia virus (Hartley & Rowe, 1966; Bassin et al. 1968; O'Connor & Fischinger, 1968).

Common genetic alterations of RNA tumour viruses grown in human cells.

Growth of serologically distinct murine RNA tumour viruses in human cells results in the acquisition of common viral surface antigens that are genetically stable. The altered viruses are able to replicate much more efficiently than the parent viruses in human cells. These findings can best be interpreted on the basis of recombination of viral and human genetic information.

Transformation and virus growth by murine sarcoma viruses in human cells.

IN the study of neoplastic transformation of human cells in culture, the quantitative systems so far described have used only the DNA-containing tumour viruses SV40 (ref. 1) and adenovirus type 12 (ref. 2). Various factors, both genetic3 and environmental4, influence the efficiency of transformation with these viruses. We describe here a quantitative transformation system using an RNA-containing tumour virus, murine sarcoma virus (MSV)5. The transformation of human cells by MSV is inefficient, but in optimal conditions (logarithmically growing cells and certain highly susceptible cell strains) both cell transformation and virus growth can be demonstrated.

An Active Interferon Inducer Obtained from Hemophilus Influenzae Type B

Abstract An extract was prepared from Hemophilus influenzae type b which induced significant interferon production both in vitro (human skin fibroblasts) and in vivo (mice). When compared to the endotoxin of Salmonella enteritidis the H. influenzae extract was 10 times more active in inducing interferon in human cells, 10,000 times more active in inducing cellular resistance to vesicular stomatitis virus in human cells and 300 to 1000 times less toxic in inducing lethality in mice and dermotoxicity in rabbits. The antiviral activity of the extract was not affected by ribonuclease, deoxyribonuclease or trypsin but was partially reduced by incubation at 25°C or 37°C. The chemical structure of the active substance of the H. influenzae extract has yet to be defined.

Abortive infection of human cell cultures by a canine adenovirus.

SummaryThe abortive infection of human amnion cells by infectious canine hepatitis virus (ICHV) was studied. Within 48 hr after inoculation, large quantities of complement fixing (CF) antigen were produced, although infectious virus yields were small. Serial passage of ICHV in human cells, with harvests every 48 hr, resulted in a rapid decrease in infectious virus, but a relatively slow decrease in CF antigen production. If the amount of input infectious virus is taken as a reference, calculations indicate that the ratio of CF antigen per infectious unit increased with each serial passage. This phenomenon was most noticeable after the first serial passage in human cells, or when low multiplicities of infection with ICHV were used. Viral antigens and infectious virus recovered from human cell cultures were found to be the result of de novo synthesis. The mechanism of the phenomenon of the nonparallel production of viral antigens and infectious virus in human cells is unknown, but possible explanations are ...

Inhibition of Sindbis virus plaque formation by extracts of Escherichia coli.

Vilcek, Jan (New York University School of Medicine, New York, N.Y.), and John H. Freer. Inhibition of Sindbis virus plaque formation by extracts of Escherichia coli. J. Bacteriol. 92:1716-1722. 1966.-Extracts prepared from washed cells of Escherichia coli B by sonic treatment and subsequent filtration through a 0.45-mu membrane filter significantly inhibited plaque formation with Sindbis virus in cultures or primary chick embryo cells up to a dilution of 1:20,000. The inhibitor acted on the cells rather than directly on the virus. The inhibiting substance was nondialyzable. Treatment of crude extracts with nucleases, trypsin, chymotrypsin, pepsin, or ether had no effect on the activity. Treatment with pronase destroyed the virus-inhibiting effect. Extracts prepared from two strains of E. coli B and one strain of E. coli K-12 all showed inhibitory activity against Sindbis virus. The inhibitor was present in the cytoplasmic fraction of bacteria. It was also active against Sindbis virus in human cells and showed some activity against vesicular stomatitis and vaccinia viruses in different types of cells. Interferon was not shown to be involved in the inhibition, although actinomycin D partially reversed the inhibitory activity of the extracts.

AMINO ACID REQUIREMENTS OF HERPES SIMPLEX VIRUS IN HUMAN CELLS.

Tankersley, Robert W., Jr. (Medical College of Virginia, Richmond). Amino acid requirements of herpes simplex virus in human cells. J. Bacteriol. 87:609-613. 1964.-Progressive infection of human cells minimally infected with herpes simplex virus requires 11 of the amino acids of Eagle's medium, and glutamine. Lysine is not required, but rather exerts a partially inhibitory effect upon virus multiplication. Infected cells deprived of arginine support neither cytopathogenic effects nor virus replication; when arginine is replaced, a prompt and extensive infection follows. The effect of nutritional deficiencies on virus infection is discussed.

Propagation of Bunyamwera. West Nile, Ilheus, and Br I viruses in human cells in tissue culture.

Summary1. Bunyamwera virus was grown in roller-slide tissue cultures of human lymph nodes (fibroblastic type cells). Propagation of virus was demonstrated by increases in virus titers in short-term virus growth studies, by long persistence of virus in tissue cultures as contrasted with rapid disappearance in cell-free preparations, and by persistence of virus after serial passages had diluted the original virus inoculum far beyond its minimal infective dilution. 2. Similar but less extensive studies demonstrated the propagation in human fibroblast tissue cultures of West Nile, Egypt 101, Ilheus, and Br I viruses. 3. Bunyamwera virus showed changes interpreted as an adaptation phenomenon during serial passages in tissue cultures. These changes were reversed by serial intracerebral passage in mice. 4. None of these viruses caused appreciable cytopathol-ogy under these experimental conditions, even after prolonged growth in tissue culture. 5. Bunyamwera, Egypt 101, and Ilheus viruses were also grown in tissu...