“HIV VIRUS

Human immunodeficiency virus (HIV) is the retro-virus responsible for the clinical spectrum of the acquired immunodeficiency syndrome (AIDS). Once infected by the virus, an individual is said to be HIV-positive. HIV then attacks and progressively destroys key elements of the immune system, rendering victims susceptible to a host of opportunistic infections and rare cancers. The development of one or more of these characteristic illnesses is what defines AIDS. “HIV/AIDS” is used to refer to the entire spectrum of disease progression from onset of infection through the advanced stages of illness.

The emergence of HIV/AIDS grew into the first worldwide epidemic since the influenza outbreak of 1918 to 1919. Unlike influenza, which struck more or less uniformly, the epidemiology of HIV/AIDS has been remarkably varied and dependent on a complex array of sociocultural elements. Politics, poverty, sexual behavior, science, and gender all conspire to produce measurable disease effects on individuals, communities, and nations. The holistic perspective of contemporary anthropology is central to understanding and managing the enormous impact of this global pandemic.

Biology of HIV

The Virus

There are two primary subtypes of HIV, designated HIV-1 and HIV-2. HIV-1 is the predominant form worldwide, while HIV-2 is limited mostly to West Africa. Both belong to a broader family of retro-viruses and contain two identical RNA strands as their genetic material. A unique enzyme, reverse transcriptase, allows retroviral RNA to be copied to DNA that then integrates within a host cell. The genomic organization of HIV is similar to other retroviruses but also has a striking predilection for genomic variability that contributes to diversity in phenotype and cell tropism. This genomic mutability is a major obstacle to the development of vaccines and effective antiviral therapies.

Infection and Life Cycle

The surface protein coat of HIV preferentially binds with a subset of circulating immune system cells known as T cells. T cells are essential for immunosurveillance and disease control, with a variety of important functions. Both T cells and macrophages (as well as some other cell populations) contain a high-affinity HIV receptor called the CD4 antigen. Once inside a host cell, HIV replication begins, and vast numbers of new particles are released, killing the host cell in the process. Newly created particles bind and infect other CD4 cells.

Clinical Phases

Acute infection is sometimes marked by “flu-like” symptoms known as the acute retroviral syndrome. Symptoms are often unrecognized by the victim or by health care professionals. The viral load is initially high, and people in this stage are capable of transmitting the virus to others. Antibodies are made to HIV but take weeks to months to develop. This interval between the onset of infection and the rise of measurable antibodies is referred to as the “window period,” a clinically important time where seronegative individuals can be infectious. The antibodies are usually detectable within 3 to 6 months.

As the immune defenses activate against HIV, a balance is struck between virus and host, but inexorably, the virus eliminates immune cells faster than they are replaced. The process can take several years. During this ...