CENTERS FOR DISEASE CONTROL AND PREVENTION
                       HIV/AIDS PREVENTION
           CDC NATIONAL AIDS HOTLINE TRAINING BULLETIN
.................................................................
 
April 8, 1994
 
 
           LATEST UPDATE:  HIV-1 Variant from Cameroon
 
 
The following information is provided by CDC as a result of
inquiries regarding "HIV-1 (type O) strain":
 
About 4 years ago, investigators from Belgium described an
unusual HIV variant from Cameroon.  This particular HIV-1 variant
(group O) is quite unusual.  It has been found primarily in
persons from Cameroon and in Europeans who have had sexual
contact with persons from Cameroon.  Even in Cameroon, the
variant is uncommon, accounting for less than 10 percent of all
HIV strains.
 
Although the evolution of this variant falls under the family of
other HIV-1 strains, its relationship with these strains is
rather distant.  It also bears some relationship with a strain of
simian immunodeficiency virus found in chimpanzees.  Two
manuscripts published in Journal of Virology in March 1994,
described additional examples of this variant in persons from
Cameroon.  One of these papers states that this variant accounts
for 7-8 percent of HIV-1 infections at a hospital in Yaounde. 
The virus must be assumed to be pathogenic, since at least some
of the infected patients have AIDS.  The Cameroon variant has
been designated as belonging to "clade O" (or subtype O) in the
HIV-1 classification system published by Los Alamos National
Laboratory.
 
Available information indicates that this variant is not reliably
detected by HIV-1 antibody assays that use peptide or recombinant
protein antigens.  U.S. blood banks use an HIV-1 assay that uses
a recombinant antigen to screen about 70 percent of donated
blood.  An abstract of a French study indicates that a European
version of this recombinant antigen assay detected only four of
six Cameroonians infected with this virus.  (This study will soon
be published in "Lancet.")  Apparently, antibodies to this strain
of HIV can be detected with assays that use whole viral lysate as
antigen, but the viral lysate test kits licensed in the United
States have not yet been evaluated for this purpose.
 
**At present, it is unlikely that the existence of this variant
represents a significant public health problem in the United
States.**   Few persons from this part of Africa are likely to
donate blood in the United States, and those who volunteer are
likely to be deferred because they come from malarious areas. 
Nonetheless, more information is needed about the sensitivity of
HIV antibody assays in the detection of this variant.
 
CDC has been in contact with officials of the Food and Drug
Administration (FDA) and the American Red Cross, and has
contacted several European investigators regarding the
availability of sera for performing studies.
 
 
DHA,NCID,CDC