Second International Congress Drug Therapy in HIV Infection 18-22 November 1994 Glasgow, UK

PROPHYLACTIC VACCINES FOR HIV; PROGRESS AND PROSPECTS

Lewellys F. Barker
Division of AIDS, NIAID, NIH, Rockville, MD, USA

Int Cong Drug Therapy HIV 1994 Nov 18-22;2:Abstract No. 15.1
AIDS 1994, Vol. 8 (Suppl. 4);S13

In almost 10 years of research, scientists have identified promising leads as well as formidable obstacles to development of a safe and effective HIV vaccine. Encouragement comes from (a) successful immunization of animals against other retroviruses, (b) limited successes with both passive and active immunization of chimpanzees against challenge with HIV, (c) an extensive record of short-term safety and some encouraging immune responses in early human trials of experimental vaccines and (d) evidence suggesting that the host immune response to acute HIV infection and in some chronically infected persons is associated with at least temporary containment of the virus. The lack of people who recover from acute or chronic HIV infection, however, leaves us with no example of naturally acquired immunity to HIV and precludes identification of markers of a convalescent immune state that might correlate with resistance to subsequent exposure. We also lack a convenient animal model of HIV disease, and we face a virus with extraordinary genetic and antigenic heterogeneity, which can spread in either the cell-free or cell-associated state, and which integrates with the DNA of infected host cells. Most vaccine experience in humans to date is with Phase I/II trials of recombinant DNA-made, monomeric subunits of the HIV envelope, and with poxvirus vectored envelope subunit antigens. Both humoral and cellular immune responses of variable magnitude, breadth and duration have been seen, and efforts are in progress to optimize these responses with various immunogen combinations, adjuvants and regimens. Other concepts under development include viral envelope peptides and multiple viral components delivered as pseudovirions and as DNA-vectored immunogens. In the SIV model, an experimental live, attenuated vaccine made by multiple genome deletions has produced the most promising protoction against challenge to date. Vaccine developers are seeking clues to the most desirable vaccine-induced immune response from human, animal and in vitro studies of virus neutralization, monoclonal antibodies, cytotoxic T lymphocytes and virus heterogeneity. Current preclinical and clinical research progress suggests that, although a veccine may be possible, the R & D road will be long and tortuous, and other approaches to preventing the spread of HIV deserve very high priority at this time.

Presenting author: Lewellys F. Barker

1994-11-18
15.1

Originally published in AIDS Volume 8, Supplement 4 and hosted with permission of the publisher Lippincott Williams & Wilkins, 250 Waterloo Road, London, SE1 8RD, UK. Tel: +44 (0)20 7981 0700 Fax: +44 (0) 7981 0701

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