01
Transmission
HIV can be transmitted through blood, semen, vaginal or rectal fluids, and breast milk. It is not spread by air, water, insects, casual contact, or sharing food.
Detailed lesson · Retrovirus
HIV-1
Human immunodeficiency virus type 1
A retrovirus that targets immune cells and can lead to AIDS.
FamilyRetroviridaeGenomeTwo copies of single-stranded positive-sense RNA
01
HIV-1 primarily targets cells carrying the CD4 receptor.
02
The virus changes rapidly because replication is error-prone.
03
HIV testing is the only way to know whether a person has the infection.
01 · Specimen
Explore the virion
Rotate the specimen, inspect its form, and shift into X-Ray mode.
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02 · Context
Overview
HIV-1 attacks the immune system, especially CD4 T cells. Without treatment, progressive immune damage can lead to acquired immunodeficiency syndrome (AIDS), but modern therapy allows most people with HIV to live long, healthy lives.
03 · Taxonomy
Classification
HIV-1 belongs to the family Retroviridae, genus Lentivirus. It is distinct from HIV-2 and is responsible for most HIV infections worldwide.
- Family
- Retroviridae
- Genome
- Two copies of single-stranded positive-sense RNA
- Host
- Humans
- Size
- About 100–120 nm in diameter
- Discovery
- Isolated in 1983 and confirmed as the cause of AIDS
- Transmission
- Sexual contact, blood exposure, and transmission during pregnancy, birth, or breastfeeding
04 · Anatomy
Structure
The physical architecture and genetic material of the pathogen.
HIV-1 is enveloped and roughly spherical. Its membrane carries gp120 and gp41 proteins used for cell entry, while a cone-shaped capsid surrounds the RNA genome and viral enzymes.
05 · Health
Disease information
Clinical presentation, risk reduction, and approaches to care.
02
Symptoms
Early infection may cause a brief flu-like illness or no noticeable symptoms. A long symptom-free period can follow, while untreated infection gradually weakens immunity and allows opportunistic infections and certain cancers to develop.
03
Prevention
Condoms, sterile injection equipment, regular testing, pre-exposure prophylaxis (PrEP), and post-exposure prophylaxis (PEP) reduce risk. Effective treatment during pregnancy and breastfeeding greatly lowers transmission to infants.
04
Treatment
Combination antiretroviral therapy blocks HIV at several stages of its life cycle. Treatment does not eliminate the integrated virus, but it can reduce blood virus levels to undetectable; people who maintain an undetectable level do not transmit HIV through sex.
06 · History
Timeline
Defining moments in research, discovery, and public health.
The first cases of the syndrome later called AIDS are officially reported.
Researchers isolate the retrovirus now known as HIV-1.
Effective combination antiretroviral therapy transforms HIV care.
07 · Curiosities
Interesting facts
HIV becomes a permanent part of an infected cell’s genetic material through integration.
The viral capsid is shaped like a cone rather than a regular icosahedron.
Studying rare people who naturally control HIV has revealed important clues about protective immune responses.
08 · Further reading
References
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