I have read different peer reviewed papers where results show that the immune response of fish against helminth parasites is weak. I am puzzled as to whether all hosts show same response or if they differ.
Dear Ummer Rashid Zargar, this is very interesting question. In mammals, immunity against helminths is mediated by IgE and IgG via binding to eosinophils and other FcR-bearing cells by the mechanism simular to induction of immediate anaphylactic reaction. The production of these immunoglobulins requires class switch recombination (CSR). In the evolution, CSR can be first identified in amphibian. In fishes CSR is absent and their immunoglobulin molecules are represented by IgM-like ones. I think, although FcRs and cellular participants can be found in fishes, the bioavailability of IgM-like molecules is too low for providing effective protection against helminths localized in tissues. This explanation is rather hypothetical, but may be reasonable at some extent. I would recommend you the review by J. Stavnezer and C. Amemiya devoted to evolution of CSR. http://www.umassmed.edu/mgm/uploads/stavnezeramemiya.pdf
@ Dmitry Kazansky. Thanks Sir for your nice comments. So, your point is that it is not clear whether some cellular molecules which act as immune defence in fishes show some response. Can we say that ambiquity still prevails.....
My another question is! Does immune system show the same response against the bacterial and viral diseases?. Can we say helminths mask the host immune system of fihes?.
@ Dmitry Kazansky. Why some fish species are more exposed to helminths and other are not. For example, here in our region i.e Kashmir we have seen that Cyprinid fish show less helminth infection in comparison to native fishes. Isn't there correlation between immune system of fish and helminth infection. Or can we say that immunology plays less role ?
Hi, Ummer! 1) Certainly, there is no sufficient information on this issue. I would not say, that immunity against helminths works well even in mammals. You can verify it in fishes estimating the levels of eosinophils in the blood. Hope, your studies will clarify this. 2) Partially in mammals (antibodies work well in both cases), but overall mechanisms are different. I think, nobody knoiws as it takes place in fishes. 3) It may take place in mammals, but represents fully unknown matter in fishes.
Dear Ummer, you can recognize any phenomenon as immunological, if you see or can demonstrate two key properties of immunity: 1) specificity (to any kind of infection), and 2) immunological memory. At present, I can not see both. I think, you should look to so called "natural (or constitutive) immunity" (innate resistance of different species to one or another infection). This approach may be more productive.
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