You know what astounds me about this discussion? And about doctors who say its not possible to have two different physical reactions to the same virus?
We have a living, breathing, example that this is false with HSV 1 and HSV 2.
All of medical science acknowledges that between the two, 80% of the human population is carrying at least one. Yet they also state that something like 80% of that group NEVER have a SINGLE SYMPTOM. And what is different between the two groups? Immune function. Maybe something else.
Well said, PhoenixBurger.
There are many reasons why the same viral infection might cause severe disease in one person, and no disease at all in the next person. These reasons include:
(1) Host genetic makeup is a factor that plays an important role in whether a virus causes a disease or not:
• For example,
herpes simplex virus has been linked to Alzheimer's, but only in people who carry the APOE-4 gene (this gene enables the herpes virus to enter the brain). In people without the APOE-4 gene, having a herpes simplex infection is not associated with getting Alzheimer's.
• In mice, Crohn's disease can be precipitated by a
norovirus infection, but this only happens in mice that have a very specific variant of the ATG16L1 gene.
• Even the
HIV virus can have a range of effects: the majority of people will develop AIDS and die if they catch HIV and do not take anti-retroviral drugs. However, some people possess the CCR5-delta32 allele which gives them total immunity to developing AIDS if they catch HIV. The CCR5-delta32 prevents the HIV from entering cells.
So host genes play a role in determining the effects of an infection.
(2) Viral genes and serotypes also play a fundamental role in whether the virus causes disease or not:
• Human herpes virus 6, variant B (HHV-6B) is found in nearly all the population, and is considered more benign HHV-6. BY contrast,
human herpes virus 6, variant A (HHV-6A) is found in only 3% of the population, and is though to be a far more vicious version of this virus. Nearly all tests for HHV-6 do not distinguish between the A and B variants. So two people could test positive for an active HHV-6 infection, but only one of them may have the A variant, and it is that person with the A variant that is more likely to get a disease like ME/CFS from it. Ref:
1.
(3) Partial reactivation of viruses. Another important issue with chronic smoldering viral infection is whether these viruses might be just partially reactivated. Some researchers think that partial reactivation of viruses is more problematic than full reactivation, and that diseases like ME/CFS may be caused by partial reactivation:
• For example: some new evidence suggests that some subtypes of ME/CFS may be caused by
partial reactivation of Epstein-Barr virus. Refs:
1 2
• Then there is the very interesting work of Dr Kazuhiro Kondo in Japan, who has theorized that a partial reactivation of HHV-6 may be responsible for causing ME/CFS, major depression, and bipolar disorder. Ref:
1.
(4) Two or more microbes may work in tandem in the host body:
• For example, Chlamydia pneumoniae and cytomegalovirus have symbiotic relationship (Chlamydia pneumoniae processes cholesterol in such a way that favors cytomegalovirus infection). So if you catch cytomegalovirus, you may only get a disease if you already have Chlamydia pneumoniae in your system. Ref:
1.
In summary: there are many reasons why a viral infection might cause severe disease in one person, and no disease at all in the next person. These reasons include:
(1) Host genetics
(2) Virus genetics and subtypes
(3) Infections where there is partial viral reactivation (which may be worse than full reactivation)
(4) Two or more microbes may work in tandem to create disease.
