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A small proportion of humans show partial or apparently complete innate resistance to HIV, the virus that causes AIDS. [1] The main mechanism is a mutation of the gene encoding CCR5, which acts as a co-receptor for HIV. It is estimated that the proportion of people with some form of resistance to HIV is under 10%. [2]
HIV can survive at room temperature outside the body for hours if dry (provided that initial concentrations are high), [31] and for weeks if wet (in used syringes/needles). [32] However, the amounts typically present in bodily fluids do not survive nearly as long outside the body—generally no more than a few minutes if dry. [23]
HIV can infect a variety of immune cells such as CD4 + T cells, macrophages, and microglial cells. HIV-1 entry to macrophages and CD4 + T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells' membrane and also with chemokine co-receptors. [26] [44]
The switch of HIV to the human host is of this type. Alternatively, in the case of a multi-host parasite host-shift may occur as a gradual change of the relative role of one host species, which becomes primary rather than secondary host. The former primary host slowly becomes a secondary host, or may even, eventually, be totally abandoned.
These cells express a CD4 receptor, to which HIV can bind, through the gp120 and gp41 proteins on its surface. [10] HIV also requires a second co-receptor along with the CD4-gp120 complex to enter the target cells - either CCR5 or CXCR4. [10] This demonstrates an example of how cell surface receptors can affect the tropism of a viral pathogen.
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Typically, these host cell proteins are endocytosed and the bound virus then enters the host cell. Virulent viruses such as HIV, which causes AIDS, have mechanisms for evading host defenses. HIV infects T-helper cells, which leads to a reduction of the adaptive immune response of the host and eventually leads to an immunocompromised state ...
By MEGAN BARRETO Fears are soaring after NYC got news of a doctor testing positive for Ebola on Thursday. And on top of the diagnosis, it was revealed that 33-year-old Dr. Craig Spencer went ...