Why the long latent period?

Article Abstract:

The median time from infection with HIV (human immunodeficiency virus) until AIDS symptoms appear is eight years. This long latent period raises questions concerning the ways the infection progresses. Whether a weakened immune response is the result, or the cause, of HIV's eventual triumph, and the ways HIV variants are handled by the immune system, are of particular concern. One model of AIDS development postulates that disease results only after several HIV variants have multiplied above a critical threshold. RNA viruses (HIV is such a virus) take on a variety of sequences, and individual CD4-positive T cells (the cells of the immune system that destroy them) are specialized to fight only one variant. The model includes a formula to calculate the rate at which the viral load increases. According to the model, the immune system successfully controls one variant after another, until the increasing number of variants overwhelms it. From this point on, all variants escape detection by the immune system. Thus, it is viral diversity that ultimately causes the downfall of the immune system. Research should therefore be targeted against HIV variants, rather than against the predominant viral sequences that have been isolated so far. Tests of the hypothesis necessitate immunologic methods to evaluate viral antigenicity (the viral segment that generates the immune response), not simply viral RNA sequences. These tests are complex, but essential, since many variants do not elicit an immune response. A strategy is presented for carrying out such tests. (Consumer Summary produced by Reliance Medical Information, Inc.)

Development and progression, HIV infection, HIV infections, AIDS (Disease), HIV antigens

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Do antibodies enhance the infection of cells by HIV?

Article Abstract:

Antibodies produced by cells in response to viruses can be of two types, neutralizing or enhancing. Neutralizing antibodies block the entry of a virus into cells, whereas enhancing antibodies facilitate movement of the virus into cells, where the virus can then replicate and cause infection. There is some evidence for the presence of enhancing antibodies in infection by human immunodeficiency virus (HIV) in culture (in vitro), but there are discrepancies among results obtained by different researchers. There is no evidence that enhancing antibodies occur in live animals (in vivo). However, the existence of enhancing antibodies in HIV infection must be examined thoroughly before vaccines or immunotherapy can be used against the AIDS disease.

Complications and side effects, Virus diseases, Immunoglobulins, Viral vaccines

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Mimicking ligands

Article Abstract:

The finding that 225 anti-CD4 receptor antibodies do not precisely mimic the binding of HIV-1 glycoprotein gp120 is questionable since intermediate steps in the characterizing of receptors may justify this method of obtaining anti-idiotypic antibodies. Moreover, more accurate testing procedures may detect usable mimics. However, the rebuttal view is that these antibodies are functional rather than structural mimics as is required. The actual occurrence of true mimics is too rare to be useful.

Glycoproteins, Immunoglobulin idiotypes

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