United Biomedical Inc.'s (UBI) V3 loop peptide vaccineproduced antibodies that could neutralize a primary fieldisolate of HIV-1 in three of 10 patients receiving a low dose ofthe vaccine, the company reported Sunday at the annualNational Institutes of Health conference on Advances in AIDSVaccine Development. Held in Alexandria, Va., the conferenceruns through Thursday.
Bruce Forrest, UBI's director of clinical development, said noother vaccine has produced neutralizing antibodies against theprimary field isolate of HIV, which is a strain taken directlyfrom an HIV-infected individual.
Forrest explained that other vaccines have generatedneutralizing antibodies against standard laboratory strains ofHIV. He said these strains are repeatedly grown on T cell lines,and thus become adapted to the laboratory and are differentfrom strains in humans. He also noted that the primary HIVfield isolates do not infect chimps.
According to Forrest, before UBI presented its data at theconference, a consensus was forming among attendees that itmight not be possible to develop a vaccine that can produceneutralizing antibodies against a primary field isolate of HIV.He said that only in the past 12 months have doubts arisen asto whether a vaccine's efficacy against a lab strain is a"reasonable indicator" of what is likely to occur in humans.
The Phase I NIH-sponsored trial involved 36 patients whoreceived either 20 mcg, 100 mcg or 500 mcg of peptide orplacebo. Three of 10 patients receiving the 20-mcg doseproduced an antibody response to the primary field isolate ofHIV.
Researchers have not evaluated data from the other two dosagegroups, but Forrest said they expect to see more respondersand better responses at the higher doses. He said they did notexpect to see an antibody response with the 20-mcg dose.
The trial, funded through NIH's AIDS Vaccine Evaluation UnitGroups, began in February and involved low-risk HIV-negativevolunteers. Another Phase I trial is under way at San FranciscoGeneral Hospital involving high-risk HIV-negative volunteers; athird trial is under way in Sydney, Australia.
In addition to its single-component HIV-1 vaccine, UBI ofHauppauge, N.Y., is also developing a multicomponent vaccinethat consists of eight V3 loops from HIV isolates from all overthe world. At the NIH conference, the company announced thatthis multicomponent vaccine neutralized primary HIV-1 fieldisolates in animals.
The company also is developing a series of peptides thatcontain epitopes for cytotoxic T cells. UBI anticipates beginningclinicals with this cellular immune component next year to seeif it induces cytotoxic T cells.
UBI's goal is to develop a vaccine that includes the single V3loop peptide, the multicomponent and the cellular immunecomponent, all bundled together in a new oral-delivery system.The company hopes to put the components together in thethird quarter of 1994 and begin efficacy studies in 1995.
-- Brenda Sandburg News Editor
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