Abstract:
Human immunodeficiency virus type 1 (HIV-1) subtypes
are distributed unevenly across African nations.1 In East
and Central African countries such as Uganda, Rwanda, Kenya,
and Tanzania, the HIV-1 epidemic has involved two HIV-1 subtypes,
A and D. In contrast, HIV-1 subtype C has dominated
the rapidly expanding epidemic in Malawi and South Africa.1-3
The relative roles played by virological, behavioral, and host
determinants in the epidemic expansion of any particular HIV-
1 subtype are unclear. Characterization of the transmissibility
and pathogenic potential of distinct HIV-1 genetic subtypes is
currently under investigation in many regions of the world.
Careful surveillance of genetic subtypes prevalent in a given
population is one particularly important approach to better understand
the biological properties of different HIV-1 subtypes.
The presence of HIV-1 subtypes A and D in asymptomatic
carriers and AIDS patients from several geographical locales in
Tanzania has been previously described.4-7 An analysis of samples
collected in 1988 showed that 10 of 15 (67%) envelope
V3 sequences from Tanzanian samples were found to belong
to subtype D. The remaining five samples (33%) belonged to
HIV-1 subtype A.4 In Dar es Salaam, vpu and env sequences
from 8 of 10 AIDS patients (80%) clustered with subtype D
viruses and the remaining 2 (20%) with subtype A.5 A study in
northern Tanzania reported that the env-encoded gp41 regions
from 12 samples also clustered with HIV-1 subtypes A and D.6
In another report from northern Tanzania, four of eight (50%)
envelope sequences sampled encompassing the C2V3 region
belonged to subtype A and the other half to subtype D.7 Envelope
sequences from HIV-1-infected individuals of Tanzanian
origin, but living in Sweden, showed that three of four samples
were HIV-1 subtype C and the remaining sample was HIV-1
subtype A.8
