What I understand about cross-immunoreactivity is that the antibody induced by one specific antigen is also fairly effective against another antigen. How would this be used for vaccine development?

Moreover, cross-immunoreactivity is related to epitopes. And how is how is cross-immunoreactivity defined among epitopes? Are variants of a specific virus hypervariable region some kinds of epitopes? What does antigenic convergence have to do with cross-immunoreactivity? Any comments or directions to further references are greatly appreciated.

  • $\begingroup$ Welcome to Biology! I tried to edit your question to clarify. What do you mean with "And how is it defined among epitopes?" - How is what defined (i.e., where does 'it' refer to)? $\endgroup$
    – AliceD
    Commented May 19, 2015 at 0:46
  • $\begingroup$ how is cross-immunoreactivity defined among epitopes? thanks for your help. $\endgroup$ Commented May 19, 2015 at 0:54
  • 1
    $\begingroup$ Probably this article will help you somewhat. jimmunol.org/content/189/9/4602.full It is hard to find anything in the topic. Probably with further search... Btw this molecular mimicry is the cause of many autoimmune diseases. scholar.google.com/… $\endgroup$
    – inf3rno
    Commented May 19, 2015 at 1:09
  • $\begingroup$ I edited the question again a bit using your comment. Feel free to make further additions or clarifications! Thanks. +1 $\endgroup$
    – AliceD
    Commented May 19, 2015 at 1:15

1 Answer 1


Cross-immunoreactivity is just as you stated where an antibody that is specific to one antigen may recognize another antigen. I don't think this term is widely used as I see cross-reactive or broadly reactive more often. With regards to vaccines against viruses, cross-reactive immune responses are very important to establish an immune response that is effective against varying strains. Using Influenza as an example, an antibody that recognizes the HA protein of the H3N2 strain and also recognizes the HA protein of the H1N1 strain would be cross-reactive. If we had a vaccine capable of this we would not have seasonal flu.

Epitopes are specific regions on the antigen that are recognized by T cells or antibodies. They are the specific area on the protein structure that is recognized. Thus, for a response to be cross-reactive that specific structure must be present on both antigens. Epitopes could be located in any region of the protein, viruses will often have a region that is highly antigenic and highly variable to trick the immune response into focusing on the highly variable region rather than the more conserved regions.

Antigenic convergence is related to the sequence space available to the virus. Since viruses have limited space for genes the amount of possible variation is limited as a single point mutation can have a large effect on the virus. Taking this into account some predictions could be made on how the virus might evolve. If the virus is evolving in such a way that there might be conserved epitopes, those epitopes might be important for cross-reactivity. Here is a paper on antigenic convergence in Hepatitis C. http://www.nature.com/articles/srep00267

This is a paper focused on flu, but it outlines the ideas surrounding cross-reactive antibody responses. http://www.ncbi.nlm.nih.gov/pubmed/26175732


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