The two major structural phosphoproteins (pp65 and pp150) of human cytomegalovirus and their antigenic properties
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Abstract:
Human cytomegalovirus (HCMV) purified from cell culture contains two dominant structural phosphoproteins with apparent molecular weights of 65,000 and 150,000, designated as pp65 and pp150 respectively. The humoral immune response of infected individuals against pp65 is relatively weak and is not always detectable by Western blot analyses. This report shows that recent clinical isolates of HCMV do not necessarily have pp65 as a prominent constituent, suggesting that the low immune reaction is due to variable expression of the pp65 in natural infections. However, the HCMV strains tested in this study produced the large structural phosphoprotein (pp150) in about equal amounts. The pp150 is remarkably immunogenic, if compared with all other virion constituents; serum pools and individual sera from HCMV-infected patients recognized this particular protein intensively in immunoblot assays. Thus, phosphoprotein pp150 seems to be the primary polypeptide candidate for expression cloning in order to develop reagents for novel ways of HCMV diagnosis.
Insights
Human cytomegalovirus (HCMV) phosphoprotein pp65 shows variable expression in infections, leading to weak immune responses. In contrast, pp150 is highly immunogenic and a promising target for developing new diagnostic tools for HCMV.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Human cytomegalovirus (HCMV) has two major structural phosphoproteins: pp65 and pp150.
- The immune response against pp65 is often weak and difficult to detect.
- Variable expression of pp65 in natural infections may explain the low immune reaction.
Purpose of the Study:
- To investigate the expression levels of pp65 and pp150 in recent HCMV clinical isolates.
- To evaluate the immunogenicity of HCMV phosphoproteins.
- To identify potential targets for novel HCMV diagnostic reagents.
Main Methods:
- Purification of HCMV from cell culture.
- Analysis of viral protein expression.
- Immunoblot assays using patient sera.
Main Results:
- Recent HCMV isolates showed variable pp65 expression.
- pp150 was consistently produced in significant amounts across tested strains.
- pp150 demonstrated strong immunogenicity, being highly recognized by patient sera.
Conclusions:
- Variable pp65 expression contributes to weak humoral immune responses in HCMV infections.
- pp150 is a highly immunogenic HCMV protein.
- pp150 is a promising candidate for developing new diagnostic reagents for HCMV detection.