Commensals provide the tonic signalling for effective innate and adaptive immune responses. After all, except for a few bad guys all are good for us!
This is a hot topic and I am looking for views on how beneficial commensals are in maintaining the balance of our immune system. People are even starting to talk about viruses as good for us. I have seen work on bacterial commensals and how beneficial they are but not with viruses. Is virus commensalism really good for humans?
This is an interesting topic. I won't address the value of commensal bacteria as this is well debated and published area. The field of viral commensals is virtually untouched to the best of my knowledge. We currently look for the pathogenic virus when disease outbreaks appear or appropriate clinical presentation dictates one do so. Should a commensal virus tune our immune system preventing infection then the clinical outcome may be no pathology, no infection, no investigation. That said, one could use cow pox and small pox as examples of protective cross immunity to justify examining epitope mimicry between commensal virus and potential pathogenic virus resulting in protective immunity. Are their biological niches where pathogenic and commensal virus coexist resulting in less severe or no infection in populations born and reared in those niches?
This is an interesting topic. I won't address the value of commensal bacteria as this is well debated and published area. The field of viral commensals is virtually untouched to the best of my knowledge. We currently look for the pathogenic virus when disease outbreaks appear or appropriate clinical presentation dictates one do so. Should a commensal virus tune our immune system preventing infection then the clinical outcome may be no pathology, no infection, no investigation. That said, one could use cow pox and small pox as examples of protective cross immunity to justify examining epitope mimicry between commensal virus and potential pathogenic virus resulting in protective immunity. Are their biological niches where pathogenic and commensal virus coexist resulting in less severe or no infection in populations born and reared in those niches?
With regards to commensal bacteria, I guess the question is still whether they have a DIRECT effect on the immune system (apart from inducing tolerance in the GALT), or whether they "just" make life difficult for the nasty and ugly ones by driving the gut microenvironment into a specific direction. There was recently a very nice article published on wider aspects of this topic, including a "stress-free" and a "stress-full" environment in pigs (see: Establishment of normal gut microbiota is compromised under excessive hygiene conditions. Schmidt B, Mulder IE, Musk CC, Aminov RI, Lewis M, Stokes CR, Bailey M, Prosser JI, Gill BP, Pluske JR, Kelly D. PLoS One. 2011;6(12):e28284. doi: 10.1371/journal.pone.0028284. Epub 2011 Dec 2.).
With regards to viruses, at least in farm animals, there doesnt seem to be a lot of "commensal viruses" present in the gut. HOwever, there are strain/subtypes/genotypes of viruses where counterparts cause disease whereas other dont - and we have no idea as yet what these viruses are doing. In addition, we all have loads of endogenous retroviral information in our genome at the end of ur life. Are these doing something for us? Do they induce some cross-protection in the widest sense?
I agree about the role of commensals bacteria in maintaining immune system but not much is known about viruses. Bacteria help us in several ways staring from fermentation to immunomodulation in body. Probiotics- health beneficial bacteria is well discussed topic in this regard. However, in general also, most of us have heard the harmless or pathogenic viruses of plant, animal or bacteria, but not about their beneficial role. We really need an answer for that weather these bugs help us in one or other way. If someone is working in this area please share knowledge. Thank you Abbas Raza for raising such an interesting question.
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