SEQUENCE-ANALYSIS OF SELECTED REGIONS OF THE ENV (V-3 LOOP AND GP-41) AND GAG (P-7) READING FRAMES OF ETHIOPIAN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 STRAINS

Amplified polymerase chain reaction (PCR) products, corresponding to the V 3 loop and gp41 of the env, and p 7 of the gag region, from proviral DNA of several Ethiopian and Swedish HIV-1 strains were sequenced. Of the six amino acids (GPGRAF) that constitute the principal neutralizing determinant (PND) within the V 3 loop, the Ethiopian isolates all showed two amino acid changes (GPGQTF). Four to five other substitutions were found in the amino acids flanking the PND. Substitution of alanine (A) for threonine (T) should result in a change in the predicted secondary structure, i.e., disappearance of a coll structure. Percentage similarity data on a stretch of 22 amino acids within the V 3 loop showed a concordance of the Ethioplan HIV-1 isolates with the sequences of published macrophage-T-cell tropic HIV isolates. Additionally derived protein sequences in two other regions showed two common substitutions in p 7 and one to two substitutions in gp41 compared to a recent consensus sequence. These changes are hitherto unique for the Ethiopian strains, and suggest the presence of a clustering of a divergent HIV-1 strain in Addis Ababa, Ethiopia.