The life cycle of HIV from entry into the human body to full-blown AIDS involves several stages:
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Entry into the Body: HIV enters the body through exposure to infected bodily fluids, typically through sexual contact, sharing contaminated needles, or from mother to child during childbirth or breastfeeding.
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Attachment and Fusion: Once inside the body, HIV attaches to and enters immune cells, primarily CD4 T cells and macrophages, using specific receptors on their surface. The virus then fuses with the cell membrane, releasing its genetic material into the cell.
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Reverse Transcription: HIV's RNA genome is converted into DNA by the enzyme reverse transcriptase. This viral DNA is then transported into the cell nucleus.
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Integration: The viral DNA integrates into the host cell's DNA with the help of the enzyme integrase. Once integrated, the viral DNA is referred to as a provirus.
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Replication and Transcription: The host cell machinery is hijacked to transcribe the viral DNA into new RNA genomes and produce viral proteins. These components assemble to form new virus particles.
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Budding and Release: New virus particles bud off from the host cell membrane, acquiring an outer envelope derived from the host cell membrane. These mature virus particles can then infect other CD4 T cells and continue the cycle of infection.
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Immune Response: As HIV replicates, it progressively destroys CD4 T cells, weakening the immune system. Initially, the immune system tries to fight the infection, resulting in flu-like symptoms during acute HIV infection.
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Progression to AIDS: Without treatment, HIV infection leads to a gradual decline in CD4 T cell count, eventually resulting in acquired immunodeficiency syndrome (AIDS). AIDS is characterized by severe immune suppression, leaving individuals vulnerable to opportunistic infections and certain cancers.
In summary, HIV enters the body, infects immune cells, replicates, and gradually destroys the immune system, leading to AIDS if left untreated.
