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Epitopes and hemagglutination binding domain on subgenus B:2 adenovirus fibers
Abstract:
The adenovirus fiber serves as a ligand between the virus and the host cell receptor and manifests hemagglutination (HA) activity and antigenic domains. We have screened both the antigenic and immunogenic epitopes on the adenovirus fibers of subgenus B:2 by using recombinant fiber proteins (rfibers) expressed in Escherichia coli, synthesized peptides (P1 to P8), and the corresponding antisera. The results indicated that P4 (amino acids [aa] 201 to 220), P5 (aa 231 to 250), and P7 (aa 275 to 295) presented both antigenic and immunogenic epitopes in adenovirus type 11 prototype (Ad11p), Ad34a, and Ad11a fibers. P6 (aa 251 to 270) presented both epitopes in Ad11a fiber but only an antigenic epitope in other fibers. The C-terminal 20 amino acids of the fiber, corresponding to P8, manifested an epitope of low-level immunogenicity. P5, localized at the N-terminal aa 231 to 250, displayed an epitope that reacted with fibers of all the members of subgenus B analyzed. The rfibers of Ad11p and Ad34a displayed HA activity with monkey erythrocytes, though those of Ad11a did not. Mutagenesis of the rfibers revealed that neither the fragment replacements, 11p20211a, llp26011a,and 11a28011p, nor the Ad11p rfiber with the substitutions of Tyr-260-->H (Tyr260H)and Arg279Q displayed HA activity. The Ad11a fiber knob was sensitive to proteolytic digestion, whereas that of Ad11p was resistant. The results demonstrated that the decisive HA binding domain was presented at aa 260 to 280 and was conformation dependent. Nearby amino acids, aa 283 and 284, may also affect the HA function.
Insights
Adenovirus fiber proteins contain key antigenic and immunogenic epitopes, with specific regions like P5 crucial for subgenus B interactions and hemagglutination activity. The study identified a conformation-dependent hemagglutination binding domain within the fiber
Area of Science:
- Virology
- Immunology
- Structural Biology
Background:
- Adenovirus fiber proteins mediate host cell attachment and possess hemagglutination (HA) activity.
- Understanding adenovirus fiber epitopes is crucial for vaccine development and antiviral strategies.
- Subgenus B adenoviruses, including Ad11p, Ad34a, and Ad11a, exhibit distinct fiber characteristics.
Purpose of the Study:
- To identify and characterize antigenic and immunogenic epitopes on adenovirus subgenus B:2 fibers.
- To investigate the role of specific amino acid regions in hemagglutination activity.
- To elucidate the structural basis of adenovirus-host interactions.
Main Methods:
- Expression of recombinant adenovirus fiber proteins (rfibers) in E. coli.
- Synthesis and analysis of peptide fragments (P1-P8) and corresponding antisera.
- Site-directed mutagenesis and proteolytic digestion assays to assess HA activity and structural stability.
Main Results:
- Peptides P4, P5, and P7 contain both antigenic and immunogenic epitopes in Ad11p, Ad34a, and Ad11a fibers.
- Peptide P5 (aa 231-250) shows cross-reactivity with all analyzed subgenus B fibers.
- A conformation-dependent HA binding domain was localized to amino acids 260-280, with nearby residues potentially influencing function.
Conclusions:
- Specific epitopes on adenovirus fibers are critical for both immune recognition and viral attachment.
- The hemagglutination activity is mediated by a distinct, conformation-dependent domain within the fiber protein.
- These findings provide insights into adenovirus tropism and potential targets for therapeutic intervention.