(above) Simplified diagram of HIV virus structure. The above image is 400 pixels across, the original measures 2200 pixels across.
Human Immunodeficiency Virus: this illustration shows the internal structure of the virion. The virus is coated (enveloped) in host cell membrane, which is drawn as a bluish green semi transparent layer in which various membrane proteins can be seen floating. Where the envelope has been cut (greenish yellow striated layer) the phospholipid molecules can be clearly seen. Beneath the viral envelope lies the matrix. The matrix proteins (MA p17gag) are drawn as trimers (bluish "Y" shaped structures) that form an icosahedral molecular cage (please see separate matrix shell picture). The viral knobs (golden projections at the viral surface) insert into the matrix. These knobs allow the virus to attach to cells. Inside the matrix shell is the conical core, drawn as a purple bullet shaped structure. Part of the core is cut away to reveal the contained genetic material (yellow). The whole virus measures about 140 nm across.
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The underlying matrix protein arrangement is based on the model for the MA shell published in: Journal of Molecular Biology (2000) 298, 841-857, Molecular Modelling Study of HIV p17gag (MA) Protein Shell Utilising Data from Electron Microscopy and X-ray Crystallography. M. J. Forster, B. Mulloy and M. V. Nermut.With many thanks to Dr Nermut for his help and advice: Milan V. Nermut MD, PhD, DSc(hon) National Institute for Biological Standards and Control (NIBSC website), Blanche Lane, South Mimms, Potters Bar, Herts EN6 3QG, U.K.