Gene Transfer Immunizes Against Monkey HIV Analog

Al writes "Researchers at the University of Pennsylvania have immunized monkeys against the simian immunodeficiency virus, the animal model that is closest to HIV. They did so by shuttling a gene into the monkeys' muscles, making the muscle cells produce antibody-like molecules that work against SIV. With both SIV and HIV, the chameleon-like mutability of the virus's surface changes so quickly that most antibodies made by the immune system are soon rendered ineffective. Philip Johnson and colleagues designed DNA sequences for two antibodies known to be effective against SIV. They used antibody-like molecules, called immunoadhesins, in which the functional part of an antibody is fused with a more stable section of another antibody. The same approach could be used to deliver antibodies that are effective against HIV, but which the body doesn't normally produce."

Comments

Whoa there, reporter cowboy.

[neapolitan]

I spent many years in medical school doing research work on viruses, including work with SIV. This article is very optimistic in some of its summaries. HIV and SIV are qualitatively different in the extent of "hypervariability" in their surface proteins. It is generally accepted to be "easier" to create antibodies to SIV, which has been done for many years.

http://www.ncbi.nlm.nih.gov/pubmed/7865316?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed

The technique described is very interesting, don't get me wrong, and I hope it works. However, there are *already* many techniques that appear to immunize against this HIV analog, which do not work for human HIV. The two are significantly different.

Re:I don't get it

[Lurker2288]

Injecting the antibodies directly does neutralize the virus, but unfortunately, the body's immune system recognizes those antibodies as foreign and so mounts an immune response against them (an anti-antibody antibody, if you like), which clears them from the bloodstream. So you'd need regular injections of neutralizing antibodies to maintain a therapeutic concentration in your blood. To quote the paper: "Passive immunization schemes using neutralizing antibodies have protected monkeys from SIV or simian-human immunodeficiency virus (SHIV) challenge infections. Unfortunately, an injection of antibodies every few weeks is neither practical nor cost effective as a large-scale human vaccine approach."