HIV Types and Strains and RT-PCR Test
We are sure that most of you would be wondering why there hasn’t been a vaccine or cure developed for HIV. In short, one of the main reasons is that HIV has many types and strains and in some cases, it forms hybrid types too. When the strains are few and limited, development of vaccine becomes possible but when there are too many strains (just like HPV – Human Papilloma Virus that has around 40 strains) development of vaccine becomes a tough task. If you are interested in knowing why there hasn’t been a vaccine for HIV, you can read the following article:
The HIV Vaccine: Why is it not there yet?
How many types of HIV exist?
Broadly, types of HIV are classified into two types:
- HIV – 1
- HIV – 2
When someone refers to HIV infection, they are most often (90% of the times) referring to HIV-1. HIV-2 type is very rare and exists only in certain population in west of Africa. The main difference between HIV-1 and HIV-2 is that HIV-2 doesn’t get transmitted to healthy people so easily (like HIV-1) and it takes a very long time to progress into AIDS.
Each of these groups have different contain viruses of different strains.
There are 4 groups in HIV-1 type:
- Group – M (Major)
- Group – N
- Group – O
- Group – P
Out of these four groups, strains in Group M are mostly responsible for the epidemic across the world. 90% of the people who are HIV positive have strains from Group M of HIV-1 group.
Subgroups in Group – M are named as A, B, C, D, E, F, G, H, J and K. These subgroups again have different strains in them. Strain B of Group M is the widely spread virus in the United States. Strain C is mostly seen in infected people in rest of the world. Most of the research is done on Strain B and not on any other strains. Drugs that work to contain Strain B of HIV also work on Strain C.
Other subgroups of HIV-1
- Group – N – Very few cases exist with this strain of virus. Most of the cases are found in Cameroon of West Central Africa.
- Group – O – This group also has too many variations like Group M. Since the cases infected with this strain are very less, not much importance has been given to study this group.
- Group – P – A relatively new group that is yet to be studied by the scientific community.
Can infected individuals have multiple strains of HIV Virus?
Yes. Virus multiplies itself after entering human cells and once they explode out of the human cells, the human cell dies. During multiplication/copying, the resulting virus may have genetically ‘mutated’ into a different strain. This results in a person having multiple strains of the virus. It is also possible that an infected person acquires infection from another infected person; a different strain of HIV may enter his/her body resulting in multiple strains. This is called ‘Superinfection’, though rare, people with this condition do exist.
When different strains are acquired by the body or developed in it, there may not be different symptoms experienced by the person. In such case, even though he/she may be using the anti-retroviral drugs, the other strain develops faster and can worsen the health condition of the person.
Before commencing the treatment or writing the prescription, it is important for the sexologist to know what type of strain the patient is carrying. It is also important for the patient and as well as the sexologist to keep checking (with blood tests) regularly the type of strains in the body. In some cases, the virus may have developed into multiple strains.
What is RT-PCR Test?
RT-PCR stands for Reverse Transcription Polymerase Chain Reaction. This is the most accurate test to check for the presence of HIV (or other virus) in a body. This is also the test that can be done even in very early stages of infection, before the development of antigens by the body. The amount of virus present in the body (Viral load) can also be determined with this test.
(Antigen test can give negative report if a person has been infected recently. But an RT PCR test can tell accurately if there the person is infected or not). Blood sample is collected from the patient and sent to lab for RT-PCR Test. Typically, the results of the test are obtained in 24 hours. This may be an expensive test compared to other tests in determining HIV infection but there are very rare chances of false positives or false negatives.
Interested in knowing about different types of tests done at different times (after infection) to confirm HIV infection? Read the following article:
What to do if you think you had sexual contact with a possibly HIV positive person?
If you think you have shared needles or had oral, vaginal or anal sex with a possibly HIV infected person, rush to your sexologist or a sex specialist near you. He/she may perform some tests and if it has been less than 72 hours after your contact, you may be put on PEP – Post Exposure Prophylaxis. These medicines prevent the virus from infecting your body. It is very common to get scared and anxious. Talk to your doctor openly and put forth all your questions and get detailed answers.
As many of you may already be aware, HIV is a life threatening infection that can devastate you mentally, physically (eventually), ruin your social life and family life. Always abstain from having sex with an unknown person. Use condoms, dental dams etc to protect yourself from such life threatening diseases.