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An in vitro assay for K-papovavirus of mice
Abstract:
Primary cultures of mouse embryo cells were inoculated with K virus, a murine papovavirus, and were examined for cytopathic effect (CPE) of for the development of fluorescent antibody staining specific for K virus V antigen. CPE was not observed. However, numerous cells in infected cultures exhibited positive nuclear fluorescence, and the presence of papovavirus virions was demonstrated by electron microscopy. Extracts from infected cultures produced typical K virus pneumonia in newborn mice. Inoculation of cultures with serial dilutions of virus demonstrated that these cells provide a fluorescent antibody assay for K virus equal in sensitivity to animal inoculation methods. Although specific K virus fluorescence was also detected in cultures of fetal mouse endocardial cells, livers, placentas, and brains, positive cells were much less abundant in these cultures than in cultures of mouse embryo cells. The mouse embryo culture assay described in the present paper represents the first method of measuring K virus infectivity in vitro.
Insights
Researchers developed a new in vitro assay for K virus, a murine papovavirus. Mouse embryo cell cultures showed positive nuclear fluorescence, enabling sensitive detection of K virus infectivity.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- K virus is a murine papovavirus known to cause disease in newborn mice.
- Previous methods for detecting K virus relied on animal inoculation, lacking in vitro sensitivity.
- Understanding K virus infectivity is crucial for studying its pathogenesis and developing control strategies.
Purpose of the Study:
- To establish a sensitive in vitro assay for quantifying K virus infectivity.
- To characterize the cytopathic effect and antigen expression of K virus in primary cell cultures.
- To compare the sensitivity of the new in vitro assay with traditional animal inoculation methods.
Main Methods:
- Primary mouse embryo cell cultures were inoculated with K virus.
- Infected cultures were examined for cytopathic effect (CPE) and K virus V antigen using fluorescent antibody staining.
- Viral presence was confirmed by electron microscopy.
- Infectivity was assessed by serial dilution and comparison with newborn mouse inoculation.
Main Results:
- No cytopathic effect (CPE) was observed in infected mouse embryo cell cultures.
- Positive nuclear fluorescence specific for K virus V antigen was detected in numerous infected cells.
- Electron microscopy confirmed the presence of papovavirus virions.
- Extracts from infected cultures induced K virus pneumonia in newborn mice.
- The fluorescent antibody assay in mouse embryo cell cultures demonstrated sensitivity comparable to animal inoculation.
- While K virus fluorescence was observed in other fetal mouse cell types, it was most abundant in embryo cells.
Conclusions:
- Mouse embryo cell cultures provide the first sensitive in vitro method for measuring K virus infectivity.
- The established fluorescent antibody assay offers a viable alternative to animal inoculation for K virus detection.
- This in vitro assay facilitates further research into K virus replication and pathogenesis.