HIV Virus Types and Strains Explained

1. Introduction to HIV

The human immunodeficiency virus (HIV) is a lentivirus that causes HIV infection and over time leads to acquired immunodeficiency syndrome (AIDS) [1]. HIV is a major global public health issue, having claimed almost 33 million lives worldwide so far. There are currently between 31.1 million and 43.9 million people living with HIV, with 1.7 million people becoming newly infected in 2019 alone [2].

2. Types and Strains of HIV

There are two main types of HIV: HIV-1 and HIV-2. HIV-1 is the most common type and accounts for 95% of all infections worldwide. HIV-2 is relatively uncommon and less infectious. The strains of HIV-1 can be classified into four groups: M, N, O, and P. The HIV-1 group M viruses predominate and are responsible for the AIDS pandemic [3].

3. HIV Classification

HIV is classified into four distinct groups: M, N, O, and P. Group M is further divided into 9 subtypes, namely A, B, C, D, F, G, H, J, and K. Subtype B is the most prevalent in the Americas, Western Europe, and Australasia, while subtype C is the most common globally, found mainly in Africa and Asia. HIV-2 has 8 known subtypes (A to H). The most common HIV-2 subtypes are A and B [4].

4. Virology of HIV

HIV is a retrovirus, meaning it has genes composed of RNA instead of DNA. The viral particle consists of two copies of single-stranded RNA enclosed by a conical capsid and surrounded by a lipid membrane envelope. The HIV life cycle involves several steps: entry into the host cell, reverse transcription of viral RNA to DNA, integration of viral DNA into the host genome, virus protein synthesis and assembly, and budding of the new virions [5].

infection“>5. Transmission and Infection

HIV is spread through contact with infected bodily fluids, such as blood, semen, vaginal fluids, and breast milk. The main modes of transmission are unprotected sexual intercourse, sharing of contaminated needles, and mother-to-child transmission during pregnancy, childbirth, or breastfeeding. Preventive measures include safe sex practices, use of pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), and harm reduction strategies for people who inject drugs [2].

6. Diagnosis and Testing

HIV testing is essential for early diagnosis and treatment. The most common tests are antibody tests (ELISA, rapid tests) and combination tests that detect both antibodies and HIV antigens. Nucleic acid tests (NAT) are used for early infant diagnosis and in cases of suspected acute HIV infection. The window period for HIV testing varies depending on the test type, ranging from 10 days to several weeks [6].

7. Impact on the Immune System

HIV primarily infects CD4 T cells, which are crucial for the functioning of the immune system. As the virus replicates, it progressively depletes CD4 cells, weakening the immune defense against opportunistic infections. The stages of HIV infection include acute infection, chronic infection, and AIDS. AIDS is defined as a CD4 cell count below 200 cells/mm³ or the occurrence of specific opportunistic infections [7].

8. HIV Treatment

Antiretroviral therapy (ART) is the cornerstone of HIV treatment. ART involves using a combination of drugs that target different stages of the HIV life cycle. The main classes of antiretroviral drugs are nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), integrase inhibitors, and entry inhibitors. ART suppresses viral replication, improves immune function, and reduces the risk of transmission. Adherence to ART is crucial to prevent drug resistance [2].

9. Living with HIV

With effective ART, people living with HIV can lead long and healthy lives. However, they may face various challenges, including managing side effects of medications, dealing with stigma and discrimination, and maintaining optimal physical and mental health. Psychological and social support, including counseling and peer support groups, are essential components of comprehensive HIV care [8].

infections”>10. HIV and Co- infections

People living with HIV are more susceptible to various co- infections, such as tuberculosis (TB), hepatitis B and C, and other sexually transmitted infections (STIs). TB is the leading cause of death among people with HIV, accounting for around one in three AIDS-related deaths. Integrated management of HIV and co- infections is crucial to improve health outcomes and quality of life [9].

11. Epidemiology of HIV

The global HIV prevalence varies considerably by region and population. Sub-Saharan Africa remains the most severely affected region, accounting for more than two-thirds of the global total of new HIV infections. Key populations that are disproportionately affected by HIV include men who have sex with men, trans gender people, people who inject drugs, sex workers, and prisoners [10].

12. HIV in Special Populations

Certain populations have specific vulnerabilities and needs in the context of HIV. Children living with HIV require specialized care, including appropriate antiretroviral formulations and support for adherence. Women living with HIV face gender-specific challenges, such as increased risk of gender-based violence and barriers to accessing services. Trans gender people and men who have sex with men often experience stigma, discrimination, and marginalization, which can hinder their access to HIV prevention and treatment services infections-in-prisoners” target=”_blank”>[11].

13. Research and Advances

Despite significant progress in HIV research, there is still no cure or effective vaccine. However, ongoing research efforts focus on developing long-acting antiretroviral drugs, novel prevention technologies (such as broadly neutralizing antibodies), and strategies for HIV remission and cure. Recent breakthroughs include the discovery of new targets for antiviral drugs and the use of gene editing techniques to modify host cells resistant to HIV infection [12].

14. Public Health and Policy

Addressing the HIV epidemic requires a comprehensive and multisectoral approach that involves governments, civil society, and international organizations. The Joint United Nations Programme on HIV/AIDS (UNAIDS) leads the global effort to end AIDS as a public health threat by 2030. Key strategies include expanding access to HIV testing and treatment, promoting human rights and gender equality, and tackling stigma and discrimination [13].

15. Historical Timeline and Milestones

The history of the HIV/AIDS epidemic spans four decades, from the first reported cases in 1981 to the present day. Key milestones include the discovery of HIV as the cause of AIDS (1983-1984), the development of the first antiretroviral drug (zidovudine, 1987), the introduction of combination antiretroviral therapy (1996), and the global scale-up of HIV treatment and prevention programs in the 2000s and 2010s [1].

16. Glossary of Key Terms

• AIDS (Acquired Immunodeficiency Syndrome): The late stage of HIV infection, characterized by a severely weakened immune system and the occurrence of opportunistic infections.
• Antiretroviral Therapy (ART): A combination of drugs used to treat HIV infection by suppressing viral replication and improving immune function.
• CD4 T Cells: A type of white blood cell that plays a crucial role in the immune system and is the primary target of HIV.
• Opportunistic Infections: Infections that occur more frequently and are more severe in people with weakened immune systems, such as those with HIV/AIDS.
• Viral Load: The amount of HIV in a person’s blood, used as a measure of disease progression and treatment effectiveness.