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Demonstration of cytomegalovirus and retrovirus pseudotypes in cultured guinea pig cells
M B Lerner-Tung1, J Y Crouch, G D Hsiung
1Yale University School of Medicine, Department of Laboratory Medicine, New Haven, Connecticut 06510.
Abstract:
A mixed viral infection with a cytomegalovirus and a retrovirus in cultured guinea pig embryo (GPE) cells was investigated. The expression of an endogenous guinea pig retrovirus (GPRV) in cultured guinea pig cells was induced by a medium containing 5-bromo-2'-deoxyuridine and dexamethasone. When the induced GPE cells were superinfected with a guinea pig cytomegalovirus (GPCMV), pseudotype virions were observed. Morphological characterization of both viruses and their locations within infected cells was achieved by examination of thin sections of infected cells with transmission electron microscopy. Immunolabeling with colloidal gold particles, 5 or 15 nm in size, permitted the identification of each virus type using GPCMV- or GPRV-specific polyclonal antibodies and the detection of a population of GPCMV and GPRV particles which expressed antigens of both viruses on their envelopes. Enhanced reverse transcriptase activity of GPRV and reduced infectivity titers of GPCMV was noted in dually infected cultures. These data suggest that interaction between GPCMV and GPRV had occurred in dually infected GPE cells and that expression of GPRV was enhanced.
Insights
This study investigated mixed viral infections in guinea pig cells, finding that guinea pig cytomegalovirus (GPCMV) and guinea pig retrovirus (GPRV) interact. Dual infection enhanced GPRV expression and affected GPCMV infectivity.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Endogenous retroviruses can be activated in host cells.
- Cytomegaloviruses are known to infect various cell types.
Purpose of the Study:
- To investigate the interaction between guinea pig cytomegalovirus (GPCMV) and endogenous guinea pig retrovirus (GPRV) in cultured cells.
- To characterize the morphological and molecular changes during a mixed viral infection.
Main Methods:
- Guinea pig embryo (GPE) cells were cultured and treated to induce GPRV expression.
- Cells were superinfected with GPCMV.
- Transmission electron microscopy and immunolabeling with colloidal gold were used for morphological and antigenic characterization.
- Reverse transcriptase activity and viral infectivity titers were measured.
Main Results:
- Pseudotype virions were observed in dually infected cells.
- Transmission electron microscopy revealed co-localization and shared antigens on viral particles.
- Enhanced reverse transcriptase activity of GPRV and reduced GPCMV infectivity titers were detected.
- A population of virions expressed antigens from both GPCMV and GPRV.
Conclusions:
- GPCMV and GPRV interact within dually infected GPE cells.
- The expression of GPRV is enhanced during co-infection.
- Dual viral infections can lead to complex interactions and altered viral behavior.
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