Complement receptors in HIV infection.
Similar to other pathogens, HIV can directly activate the complement pathway even in the absence of antibodies. During and after seroconversion, HIV-specific antibodies enhance the activation of complement and increase deposition of complement fragments on virions dramatically. However, even in the presence of HIV-specific antibodies, no or only poor lysis occurs. HIV has adapted different protection mechanisms to keep complement activation under the threshold necessary to induce virolysis. In addition to its own envelope proteins, the viral envelope contains membrane-anchored host molecules. Among those are complement regulatory proteins that remain functionally active on the surface of HIV and turn down the complement cascade. In addition, serum proteins with complement regulatory activities become secondarily attached onto the virus, thereby enhancing the protection of HIV against complement-mediated damage. Therefore, opsonised virions accumulate in HIV-infected individuals, which subsequently interact with complement receptor (CR) expressing cells. This review is mainly focused on these interactions, which result either in infection of CR-positive cells with high efficiency, or retention of viral particles on their surface via CRs, thereby promoting transmission of virus to other permissive cells.
Doepper
Susi
S
Institute of Hygiene & Social Medicine and Ludwig Boltzmann Institute for AIDS Research, University Innsbruck, Austria.
Kacani
Laco
L
Falkensammer
Barbara
B
Dierich
Manfred P
MP
Stoiber
Heribert
H
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism / Q000821:virology; D002352:Carrier Proteins; D003176:Complement C3 / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism / Q000821:virology; D006678:HIV / Q000378:metabolism* / Q000502:physiology; D015658:HIV Infections / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors; D016167:Integrin alphaXbeta2 / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement / Q000378:metabolism*; D017464:Receptors, Complement 3d / Q000378:metabolism
D015703:Antigens, CD; C087299:C1QBP protein, human; D002352:Carrier Proteins; D003176:Complement C3; D018960:Hyaluronan Receptors; D016167:Integrin alphaXbeta2; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement; D017464:Receptors, Complement 3d; C032402:complement 1q receptor; C085567:complement C3a receptor