Prepared by: Bratislav Prokić, August 2022
Review: Dr. Jovana Milić,
Metabolic clinic for HIV in Modena, Italy
What are mutations?
Mutations are errors that the virus makes during multiplication (replication). HIV reproduces rapidly, producing millions of copies every day. Small differences that each new generation of virus carries are called mutations.
Are mutations dangerous?
Most mutations are not relevant to treatment. However, mutations that occur in the parts of HIV targeted by antiretroviral drugs can be important in creating resistance to certain drugs.
What is resistance?
Resistance is a non-response to one or more antiretroviral drugs that a person is using, which means that they can no longer work effectively against the virus. In that case, a change of therapy is necessary.
How does resistance arise?
Resistance to HIV drugs occurs as a mutation during the multiplication of the virus (creation of viral copies) in the presence of antiretroviral drugs. It happens due to the insufficient concentration of drugs in the blood that cannot completely suppress the virus and prevent its reproduction.
What causes HIV drug resistance?
The most common cause of resistance is irregular and incorrect use of antiretroviral therapy, which leads to incomplete suppression, i.e. prevention of virus reproduction (viral replication). The virus will then be detected in the blood by a PCR (HIV RNA) test. The more viral copies, the greater the chance of creating mutations.
How to prevent resistance to HIV drugs?
The risk of resistance can be reduced by proper and daily use of antiretroviral drugs, with regular PCR testing every 6 months to ensure that the number of viral copies in the blood is maintained at an undetectable level (less than 50 copies/ml of blood).
What are the signs of HIV drug resistance?
A person who has resistance to HIV will have detectable viral load, that is, a PCR test will show a higher number of viral copies. Resistance is diagnosed by a resistance test.
What is done in case of suspected resistance to an HIV drug?
In case of suspected resistance, a resistance test should be performed. In case the test shows that there is resistance to certain antiretroviral drugs, it is necessary to change the therapy and get used to new drugs.
What is cross-resistance?
Resistance to one drug may mean that HIV has developed resistance to other similar drugs (from the same group) that have not been used in previous treatment. We call this cross-resistance. The resistance test will help to select, in the case of cross-resistance, those HIV drugs that will be effective in further treatment.
Can a person get or transmit a resistant strain of HIV?
Yes. If a person has detectable viral load and a resistant strain of the virus, they can transmit it sexually. Some people get HIV that is already resistant to one or more HIV drugs, which can reduce treatment options.
How do you check if someone has primary resistance to some HIV drugs?
Resistance test should be done before starting antiretroviral therapy (ART). Since it is expensive, in some clinics the blood sample is saved so that in case of failure of the prescribed therapy a resistance test can be performed later.
Can the virus develop resistance in a person who is not taking HIV medication?
HIV mutates during reproduction, but resistance to antiretroviral drugs occurs only in the case of virus reproduction and mutations in the presence of HIV drugs (in insufficient concentration).
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