HIV Vaccine - Shorts

Townsend Letter for Doctors and Patients,  April, 2002  by Jule Klotter

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Scientists have found that creating an antibody-producing vaccine that will prevent HIV from entering cells, is very difficult. Some researchers are investigating partial-protection vaccines that keep HIV levels in check by stimulating killer T-cells. Although killer T-cells cannot eradicate HIV from the body, their action is expected to prevent or delay the onset of symptoms. In his article for The Wall Street Journal, Mark Schoofs explains that infected cells display epitopes, fragments of viral proteins, on the cellular surface. When a killer cell finds the one eptiope it is programmed to seek, it replicates itself until enough killer cells exist to destroy the cell.

A test of an experimental vaccine involving eight monkeys indicates that epitope mutations may develop that render a killer cell vaccine ineffective. Harvard researcher Dan Barouch and his mentor Norman Letvin found that eight monkeys developed high levels of killer T-cells after being injected, first, with an experimental vaccine and then with "a lethal AIDS virus." The summer after those January 2000 injections, the scientists noticed that the number of killer cells geared to find epitope p11C in one of the monkeys had markedly decreased. Steven Wolinsky of Northwestern University discovered that the virus had mutated, causing epitope p11C to change shape and properties. Killer cells geared to attack p11C no longer recognized it, and they atrophied from disuse. Unfortunately, most of the killer cells generated by this monkey's immune system were geared to attack epitope p11C, and the monkey died. Current research suggests that "the immune system tends to concentrate its killer T-cells on just one or two epi topes." The Wall Street Journal article ends with a quotation from Dr. Seth Berkley, president of the International AIDS Vaccine Initiative concerning the development of an effective AIDS vaccine: "I think it's going to be a continuous improvement process for a long period of time."

Schoofs M.A. Monkey's Death Complicates Effort to Find HIV Vaccine. The Wall Street Journal 2002 January 17; A1.

COPYRIGHT 2002 The Townsend Letter Group
COPYRIGHT 2002 Gale Group