.
When a person who is already infected with HIV is exposed to the same or different strains of HIV, a second infection or multiple infections occurs, called superinfection.
.
Schematic diagram of the transmission pattern of HIV hyperinfection
1. Causes of hyper-infection
HIV is a highly variable virus that is divided into HIV-1 and HIV-2. HIV-1 can be further divided into groups M, N, O, and P. Group M is the dominant virus strain responsible for the global AIDS epidemic and includes at least 11 subtypes of A-K as well as various circulating recombinant types (CRFs). HIV-2 has at least 7 subtypes of A-G.
.
Global distribution of major HIV subtypes
In mainland China, HIV-1 is the main epidemic strain, and 10 subtypes have been discovered: A, B (Europe and the United States B), B' (Thailand B), C, D, F, G, H, J and K, as well as different epidemic recombinant types and unique recombinant types. Due to the large number of HIV subtypes, HIV hyperinfection occurs when a person with HIV is reinfected with a new phylogegenetically distinct strain of HIV, in which case two different strains of HIV can enter the same cell and form a new recombinant virus by exchanging gene fragments. In injecting drug users, the incidence of overinfection in infected people can reach 13%.
2. Adverse consequences of superinfection
While scientists generally agree that HIV hyperinfection is associated with a faster increase in viral load and has some effect on CD4 cytopenia, it does not lead to faster disease progression.
However, if a superinfected patient is infected with a drug-resistant strain for the second time, the superinfection may alter the patient's response to antiretroviral therapy and the clinical course of AIDS. Recently, there have been reports of a sudden rebound in viral load in an infected person who has been stable for more than a decade on antiviral therapy. Epidemiological history tracing and laboratory testing have found that the infected person has developed superinfection due to repeated unprotected sex with HIV-positive partners, and the new infection strain is a drug-resistant strain of a different subtype from the primary infection, and the original treatment regimen and the body's established immune system are unable to defend against the new strain, and the treatment regimen has to be changed.
.
3. Prevention of superinfection
In order to reduce the occurrence of superinfection, the emergence of new variants due to viral recombination, and the failure of treatment due to recombination, the following measures can be taken:
- Early access to standard antiretroviral therapy. Successful antiviral therapy can reduce the viral load below the limit of detection, and keeping the viral load low can both prevent transmission of HIV to others and maintain adequate immune defenses to prevent the occurrence of secondary HIV infection.
- In cases where both partners are HIV-positive, even if both are on antiviral therapy, it is still strongly recommended to use condoms during sex to reduce the probability of overinfection.
- Say no to drugs. Under no circumstances should syringes be shared.