How did AIDS come about?
There are gp120 and gp41 glycoproteins embedded in the lipoproteins of HIV (HIV) in vitro, and the CD4 glycoproteins on the surface of gp120 and lymphocytes have affinity, which can be combined with specificity. Gp41 mediated viral envelope fusion with host cell membrane. As a result, HIV can selectively invade CD4+ lymphocytes after reaching the blood through the skin mucosa or other pathways, such as blood.
After HIV invades CD4 + lymphocytes, in under the action of reverse transcriptase virus, synthesis of DNA, and integrated into the host cell’s chromosomes, integration can be viral DNA replication in a cell, form a complete virus the body to release the cells, cell death, infect new cells, can also be a latent infection status, into the daughter cells with cell division.
In the early stage of infection, the HIV replication occurs in large Numbers, resulting in viremia, and the expression of capsid antigen p24 can be found in the clinical manifestations of acute HIV infection. CD4+ lymphocyte damage, death, and CD4+T cells were significantly reduced due to a large number of replication in the cells of HIV. However, under the immune function of the body, CD8+CTL activation, killing HIV infected cells, and producing anti-hiv antibodies, the virus is quickly cleared, and the number of CD4+ lymphocytes is recovered.
However, HIV has not been completely killed, entering a persistent latent infection state, HIV is at a low level of replication, and clinical manifestations are asympto-free HIV infection. With the copy, spread HIV, CD4 + lymphocytes death constantly, so the cycle, resulting in the depletion of CD4 + lymphocytes, immune function, complicated by a variety of pathogens of infection and tumor, clinical manifestation of AIDS, and eventually death.
The origin of AIDS
AIDS originated in Africa and was brought to the United States by immigrants. The human virus may have come from wild chimpanzees in Africa. But until now, scientists have failed to understand how HIV was transmitted from chimps to humans. Most scientists believe that it is likely that humans infected with the virus have taken a bite, or have been infected with the virus when they were killed. So HIV mutates in humans, and evolves to infect others with HIV. Most importantly, the virus is significantly more lethal to humans, and chimpanzees are generally harmless.