posted 06-28-2001 09:27 AM            

HIV And Vaccines -
The Truth Matters
By Mike Nelson
MNelson_8@excite.com
6-28-1

Hi Jeff,

I know that tonight's topic with Dr. Lorraine Day on the potential for a "Forced Aids Vaccine In US" will be controversial enough so please allow me to add more food for thought (or more fuel to the fire).

Let,s get some background done first: As of May 2000, there had been over 60 phase I/II clinical trials of at least 30 candidate HIV vaccines worldwide. These initial trials were designed to test the safety and immunogenicity (ability to elicit an immune response) of the candidate vaccines. But, to date, AIDSVAX (produced by VaxGen) is the only HIV/AIDS vaccine that has reached phase III clinical trials designed to determine actual preventive efficacy in human beings.

Consider the following:

First, two versions of the vaccine are currently being tested. The version closest to completing clinical trials is based on the B subtype of Group M of HIV-1, the variant most common in Western countries. Efficacy data on a second version--based on subtype E, more common in Southeast Asia--is expected in about 18 months to 2 years.

However, for further information, there currently exists two major types of HIV, type 1 (HIV-1) and type 2 (HIV-2), as well as different groups within each type. HIV-1 is more virulent than HIV-2 and is the predominant strain around the world. HIV-1 is a highly variable virus, which mutates very readily. So much that there exist many different subtypes of HIV-1. These subtypes can be classified according to groups. There are currently four main subtype groups, group M and group O as well as the two lesser known group N and group CPZ. Please see chart below.

Within group M of HIV-1 there are currently known to be at least 10 genetically distinct subtypes. In addition, Group O of HIV-1 contains another distinct subtype of very similar viruses. The subtypes of the M group may differ as much between subtypes as group M differs from group O. Group N and Group CPZ each has two and five differing genetic sequences respectively.

HIV-1 Group M Group O Subtypes: A1, A2, B, C, D, F1, F2, G, H, J, K Two differing genetic subtypes within this group 78 distinct genetic differences among the above subtypes

Group N Group CPZ Two differing genetic subtypes within this group Five differing genetic subtypes within this group

HIV-2 is divided in the group A and B, but further groups C through E have recently been discovered.

Therefore, it is almost certain that new HIV genetic subtypes will be discovered in the future, and indeed that new subtypes will develop as virus mutation continues to occur. The current subtypes will also continue to spread to new areas as the global epidemic continues. One vaccine will not cover all the current or potential subtypes. In fact, the push for only one vaccine may give people the idea that once they are vaccinated that they can engage in risky behavior once again. But this may get them infected with another subtype of the HIV virus especially in areas of international trade. Most likely, the initial HIV vaccines will not be 100% effective, and they will have to be delivered as part of a comprehensive prevention package.

Finally, delivery of an effective vaccine in poorer nations with fragile health systems remains a great concern, given that vaccines developed for other infectious diseases have typically taken an average of 20 years to reach populations in the developing world. Let's get clean water to a majority of the world and help prevent the other majority of the world's health problems (i.e Cholera) instead of something that is a behavior-based disease and can be prevented by individuals who choose to abstain or change their risky behavior.

References

AIDS Vaccine Development: Related Resources http://hivinsite.ucsf.edu/InSite.jsp?page=kbr-08-01-11

HIV Subtypes, Types, Groups, Strains & Vaccines http://www.avert.org/hivtypes.htm

HIV Subtypes: a quick primer http://www.managingdesire.org/hivsubtypes.html

A Reference Guide to HIV-1 Classification http://hiv-web.lanl.gov/HTML/reviews/nomenclature/Nomen.html

The Science of HIV Vaccine Development http://hivinsite.ucsf.edu/InSite.jsp?page=kb-07&doc=kb-02-01-06