|
Nutrients as Anti-Bacterial and Anti-Viral agents See also essential nutrients like vitamins See also Foods as anti-bacterial and anti-Viral agents Many factors affect whether you will be more or less suceptible to viral infection and the course of a viral infection. Factors which are important include the genotype of the virus, your own ethnic background, your gender and your age. Lets take genetic background as an example since it clearly is a major factor. The importance of genetic background in viral infection has been shown in mice. To take an example, mousepox is a generalized infection caused by the ectromelia virus. This virus does nothing to the genetically resitant C57B1/6 mouse strain. In contrast, only one infectious particle of the same virus can result in 100% mortality in the sensitive BALB/c or A mouse strains. Why is this so? The reason for the difference in strain susceptibility is related to differences in the cytokine profile produced in each of these strains after infection. In the C57B1/6 strain, there is a rapid induction of type 1 cytokines (interleukin-2, interferon-y, tumor necrosis factor-alpha) which results in a potent cytotoxic T lymphocyte (CTL) immune response. However in the BALB/c or A mice these cytokines are virtually absent with a complete absence or delayed induction of a CTL response. This is just one example where certain viruses are lethal in one type of mouse strain but do absolutely nothing in other strains. Clearly the differences seem to lie in the genetic makeup of these different strains. A different genetic makeup can result in a different immune response which either confers resistance or not. Now many people will falsely say if this is the case, well there is nothing that diet can do in such cases. Well this is not completely accurate either. An example of this generally assumed belief is infection with coxsackieviru. Coxsackievirus induces a myocarditis in mice. A susceptible strain of mice (C3H/HeJ) fed a diet deficient in either Se or vitamin E develope increased cardiac pathology when infection with coxsackievirus B3 (CVB3) when compared with nutritionally adequate mice. A myocarditic strain of coxsackievirus B3 (CVB3/20) became more so and an amyocarditic strain of coxsackievirus B3 (CVB3/0) converted to virulence when the virus was incoulated into Se or vitamin E-deficient mice. In the case of the virus that converted from avirulent to virulent, the genome of the amyocarditic CVB3/0 mutated to a form closely resembling that of the myocarditic strains as a resutl of haivng been passed through either a Se or a vitamin E deficient host. Thus, the viral genoitype was altered by the nature of the diet fed to the host. But what is even more intriguing is that mice that are normally resistant to coxsackievirus-induced myocarditis by virute of their genetic makeup (C57B1/6 strain) become susceptible to the virus when they are fed a diet that is deficient in both Se and vitamin E. This implied that host genetic background as a deteminant of viral infection otucome is superseded by feeding the host a diet nutritionally defiicent in both selenium and vitamin E. Whatever the biochemical mechanism whereby dietary deficiency decreases the ability of a naturally resistant host to ward off viral infection, host nutritional status can have a profund effect on the course of viral disease. Cytokines (IL-8): Studies in human volunteers have established an association between IL-8 and common cold symptoms, In rhinovirus infections there is a direct correlation between the severtiy of common cold symptoms and the concentration of IL-8 in the nasal secretion. Flu: The main influenza strain circulating in the US has become resistant to two of the four drugs used to treat it (Amantadine and rimantadine). Tamiflu: is the generic name for oseltamivir. It is currently (but maybe not for long!) effective against all Flu strains tested at the CDC Relenza: is the generic name for zanamivir. Amantadine and rimantadine: are among the few prescribed drugs used to shorten a flu attack and ease its symptoms, making the disease less dangerous for the elderly and those with compromised immune system. But in the 2006 flue season, 91% of samples of the main flu virus circulatingin the US, known as H3N2, that were tested by the CDC have shown resistance to the two drugs. This may be due either to a mutation in the flu virus in the US or importation of a virus that had gained resistance, psossibly from Asian countires where the drugs are sold over the counter.
|
