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Cytomegalovirus-induced membrane antigens in productively infected cells
Abstract:
Adsorbed but not penetrated virus can be removed from the CMV-infected cell membrane by digestion with cystine-activated papain. Membrane antigens appear on 80-90% of the infected cells 14-20 hr after infection as a result of de novo protein synthesis. Antigen synthesis can be blocked with inhibitors of protein synthesis, but not with DNA inhibitors. In the early stage of infection, pooled human convalescent serum reacted well with the membrane antigen, whereas pooled antiserum of rabbits immunized with CMV virion suspension gave a positive reaction with a small proportion of the cells. After the 48th hr, both the human and the rabbit serum pool reacted with the membrane of the infected cells. Absorption with cell cultured for 24 hr after CMV infection reduced the neutralization titres of the antisera only slightly but the titre reduction was considerable when absorption was performed with cells cultured for more than 48 hr after infection. It is concluded that on the membrane of cells productively infected by CMV at least two membrane antigens are present, one coded for by the DNA of the parent virus and another which is the product of the DNA of the virus progeny. The two antigens can be differentiated serologically.
Insights
Cytomegalovirus (CMV) infection involves at least two distinct membrane antigens on infected cells. These viral antigens can be differentiated serologically and appear due to de novo protein synthesis.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Cytomegalovirus (CMV) is a common human herpesvirus.
- Understanding CMV-induced cell surface changes is crucial for diagnostics and therapeutics.
- Viral protein expression on infected cell membranes plays a key role in immune response.
Purpose of the Study:
- To characterize the membrane antigens expressed on CMV-infected cells.
- To investigate the synthesis and temporal expression of these antigens.
- To differentiate between viral antigens originating from the parent virus and its progeny.
Main Methods:
- Enzymatic digestion (cystine-activated papain) to remove non-penetrated virus.
- Analysis of antigen expression using pooled human convalescent serum and rabbit antiserum.
- Inhibition studies using protein synthesis inhibitors.
- Absorption assays with CMV-infected cells cultured for different durations.
Main Results:
- CMV membrane antigens appear on 80-90% of infected cells 14-20 hours post-infection, dependent on de novo protein synthesis.
- Early in infection, human convalescent serum showed strong reactivity, while rabbit antiserum showed weak reactivity.
- After 48 hours, both human and rabbit antisera reacted strongly with infected cell membranes.
- Absorption studies indicated the presence of at least two distinct membrane antigens.
Conclusions:
- Productively CMV-infected cells express at least two distinct membrane antigens.
- One antigen is coded by the parent virus DNA, and the other is a product of viral progeny DNA.
- These two antigens can be serologically differentiated, suggesting distinct roles or origins.