Summary auto-generated
Researchers used monoclonal antibodies (MAbs) to map antigenic determinants on the capsid protein of potato virus X (PVX) B strain. Using various serological tests including ELISA, dot-blot immunoassays, and precipitin tests on differently treated virus preparations, they identified three distinct groups of MAbs recognizing separate antigenic sites. Group II MAbs recognized determinants on the protruding N-terminal region, which is readily removed by proteases or trypsin. Group I MAbs recognized surface determinants outside the N terminus that are stable in native particles but destroyed by extensive denaturation with SDS or pyrrolidine. Group III MAbs recognized determinants that become exposed only upon partial denaturation of virus particles during direct attachment to ELISA plates or membranes, yet remarkably resist complete denaturation with SDS. The study demonstrates that virus particles undergo partial denaturation when attached directly to solid surfaces, affecting antibody accessibility. Similar reactivity patterns were observed with CsAg and M strains, though they lacked reactivity with some Group II and one Group III MAb. These findings suggest that differential MAb reactivity with intact versus degraded viral proteins may be important for field diagnosis of potato viruses.
Key findings
- Three distinct antigenic determinants were identified on PVX B strain capsid protein based on differential monoclonal antibody reactivity patterns
- Group II determinants are located on the protruding N-terminus and are lost upon trypsin or protease treatment
- Group I determinants are surface-exposed in native particles but destroyed by extensive chemical denaturation (SDS/mercaptoethanol)
- Group III determinants become accessible only after partial denaturation during direct attachment to solid surfaces (ELISA plates or nitrocellulose) but resist extensive denaturation
- Virus particles undergo partial denaturation when directly attached to ELISA plates, exposing normally inaccessible epitopes
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Abstract
At least three different antigenic determinants were distinguished on the capsid protein of the B strain of potato virus X by their differential reactivity with monoclonal antibodies. One determinant (or group of determinants) was located on the protruding N terminus which, in the assembled virus particles, is readily split off by proteases in crude plant sap or by trypsin. A second determinant (or group of determinants) was located outside the protruding N terminus on the surface of the undisturbed virus particles. In partially denatured preparations containing the protruding N terminus, this determinant became inaccessible. A third determinant (or group of determinants) became exposed only after some denaturation of the virus particles, e.g. when they were applied directly to ELISA plates or nitrocellulose membranes. In contrast to the other two determinants, this determinant was not destroyed by extensive denaturation, such as heating in solution with SDS and 2-mercaptoethanol.