HIV is a virus that targets the immune system, specifically white blood cells known as CD4 T cells. This viral infection progressively weakens the body’s defenses, making individuals susceptible to various illnesses. If left unmanaged, it can advance to Acquired Immunodeficiency Syndrome (AIDS), which signifies a severely compromised immune system. While there is no cure, effective medical treatments control the virus, allowing individuals to live long, healthy lives.
Defining HIV Superinfection
HIV superinfection occurs when a person already living with an established human immunodeficiency virus infection acquires a second, genetically distinct strain of HIV. This differs from co-infection, where an individual is simultaneously infected with multiple distinct viral strains, often before the body has developed an immune response to the initial infection. Superinfection, by contrast, specifically involves the acquisition of a new strain after the first infection has taken hold and the body has undergone seroconversion, meaning it has produced antibodies against the initial virus.
When two different HIV strains infect the same cell, their genetic material can combine to form a new, hybrid recombinant strain. This genetic recombination can lead to increased viral diversity. While the exact incidence rate of HIV superinfection varies in studies, reported figures range from 0% to 7.7% per year globally.
Consequences of HIV Superinfection
Acquiring a second, distinct HIV strain can have notable medical implications. One significant concern is the potential for accelerated progression of HIV disease. Superinfection can lead to a more rapid decline in immune system health, often evidenced by an abrupt increase in viral load (the amount of HIV in the blood) and a decrease in CD4 cell counts. These changes can resemble the initial acute phase of HIV infection.
A primary consequence is the introduction of new drug resistance mutations. If the newly acquired strain carries resistance to certain antiretroviral medications, it can render an individual’s existing treatment regimen less effective or even lead to treatment failure. The recombination of the original and new viral strains can further complicate matters by creating mosaic recombinant forms that exhibit resistance to multiple classes of drugs, making treatment selection more challenging. The overall clinical impact is frequently negative due to disease acceleration and drug resistance.
Managing HIV Superinfection
There is no specific cure for HIV superinfection, but its management focuses on adjusting antiretroviral therapy (ART) to address the new viral strain. Upon suspicion, healthcare providers assess the new strain’s genetic makeup and resistance profile. This typically involves genotype testing, a blood test that identifies specific genetic mutations in the virus known to confer drug resistance.
Based on resistance testing, an optimized ART regimen is selected to effectively suppress all viral strains, including the newly acquired one. Close medical monitoring, involving regular viral load testing, ensures treatment effectiveness. Achieving and maintaining an undetectable viral load is the goal, as this helps preserve immune health and prevents further transmission. A significant challenge arises if the new strain introduces extensive drug resistance, potentially limiting available treatment options.
Preventing HIV Superinfection
Preventing HIV superinfection involves strategies that reduce exposure to new viral strains. Consistent and correct use of condoms during sexual activity is a primary method, creating a barrier against HIV transmission, even when both partners are living with HIV.
Adherence to an existing ART regimen is also a significant preventive measure. By taking antiretroviral medications as prescribed, individuals can suppress their viral load to undetectable levels. An undetectable viral load improves individual health and virtually eliminates the risk of transmitting HIV to sexual partners, reducing the chance of acquiring a new strain.
For HIV-negative partners, pre-exposure prophylaxis (PrEP) offers a highly effective way to prevent HIV acquisition. For people who inject drugs, engaging in harm reduction strategies such as using sterile needles and injection equipment helps prevent exposure to new HIV strains.