Subtyping of human immunodeficiency virus type 1 strains by using antibodies specific for the third variable domain (V3) of gp120: results may be affected by divergent V3 sequences.

Human immunodeficiency virus type 1 serotype C was found in 545 of 712 Ethiopian patients by peptide enzyme immunoassay. Serotyping failed in 146 samples due to the absence of V3 antibodies or multiple reactivities. In 6 of 34 samples, discordant results were obtained by serotyping and genotyping, possibly due to divergent V3 sequences.

Multiple enhancer motifs in HIV type 1 strains from Ethiopia.

PIP: The authors determined the sequences of the LTR region of Ethiopian HIV-1 subtype C strains and compared them with Swedish HIV-1 subtype B strains and earlier published data. Peripheral blood mononuclear cells (PBMCs) were obtained from seven randomly chosen HIV-1 infected Ethiopian patients, all with pre-AIDS or AIDS. PBMCs were also obtained from three Swedish HIV-1 subtype B-infected patients. Extraction of HIV-1 DNA was performed with the phenol-chloroform plus ethanol precipitation method. In all the Ethiopian HIV-1 subtype C strains, the first five nucleotides were changed to (G/A)CAGA, a finding not observed in the Swedish subtype B strains sequenced at the same time. The most remarkable feature of the Ethiopian NF-KB region was the presence of what appears to be an extra site located upstream of the usual sites I and II. At the same time, the core enhancer sequence GGGACTTTCC at site I was modified by a deletion of the A nucleotide and a change of the first T to a G. The gross LTR organization may be radically different in "African" subtype HIV-1 isolates compared to the American/European HIV-1 subtype B prototype strains. These data from the Ethiopian strains reinforce the validity of this conclusion.^ieng

Rapid grouping of HIV-1 infection in subtypes A to E by V3 peptide serotyping and its relation to sequence analysis.

We developed a typing assay for HIV-1 using subtype specific peptides corresponding to the five major subtypes of HIV-1 (A to E). In eight patients serologically subtyped as A (n = 1), B (n = 3), C (n = 3) and E (n = 1) phyllogenetic analysis of sequenced V3 domain DNA completely correlated to the peptide serotyping. Out of 106 HIV-1 seropositive samples of a diverse geographical origin 88 (83%) could be subtyped by the peptide assay. Five were of subtype A, 33 of subtype B, 48 of subtype C, one of subtype D, and one was of subtype E. Swedish patients were mainly of HIV-1 subtype B and Ethiopian patients were mainly of subtype C, confirming the performance of the assay. Furthermore, subtype specific antibodies may persist up to nine years in HIV-1 infected patients though sera close to AIDS diagnosis may be difficult to type.

The antigen/antibody specificity exchanger: a new peptide based tool for re-directing antibodies of other specificities to recognize the V3 domain of HIV-1 gp120.

We recently showed that a synthetic peptide corresponding to the third complementary determining region of the heavy chain (CDRH3) of a monoclonal antibody (mAb) directed to the V3 domain of HIV-1 gp120 neutralizes HIV-1 in vitro. From the CDRH3 sequence we have now produced bifunctional antigen/antibody specificity exchanger (A/ASE) peptides containing both the HIV-1 mAb derived CDRH3 sequence and antigenic region sequences from the hepatitis B virus core/e antigen (HBc/eAg) and the poliovirus VP1. These A/ASE peptides were able to re-direct HBc/eAg and enteroviral VP1 specific mAbs, as well as polyclonal human HIV-1 negative sera to recognize the V3 domain of HIV-1. Furthermore, two out of three A/ASE peptides were able to neutralize HIV-1 in vitro. These bifunctional A/ASE peptides have a potential to be used as tools in research, diagnostics and maybe even therapeutics.

Evidence of no change in V3 loop antibody recognition pattern in HIV type 1-infected Ethiopians between 1988 and 1993.

To determine the antibody reactivity against a V3 sequence based on local HIV-1 strains in Ethiopia, 635 serum samples derived in 1988 and 1993 were analyzed by peptide enzyme immunoassays. V3 peptides were produced according to the Ethiopian subtype C V3 consensus sequence (RKSIRIGPGQTFYAT), the HIV-1MN and HIV-1IIIB strains (subtype B), and the consensus sequences of subtypes A, D, and E. Initial analyses showed that Ethiopian anti-V3 positive sera cross-reacted between subtype A and subtype C peptides, and displayed much lower reactivities to the other peptides. Using inhibition experiments, it was found that the reactivities in the Ethiopian samples were specific for subtype C. A strong reactivity to the Ethiopian V3 consensus sequence was found in the majority of the Ethiopian samples (59%), independent of geographical origin or year of sampling. In Swedish HIV-1-positive sera, the high reactivities were restricted to the subtype B HIV-1MN peptide. A low prevalence (10%) of strong reactivity to the HIV-1MN V3 peptide was found among the Ethiopian samples. Using substitution peptide analogs it was found that a lack of cross-reactivity between subtype B and C peptides was dependent on the Arg-322 to Gln-322 substitution. The present data show that a similar antibody recognition pattern was present in sera sampled during 1993 as in sera sampled during 1988, suggesting that subtype C of HIV-1 has remained the dominant subtype in Ethiopia.

PIP: 635 serum samples derived in 1988 and 1993 were analyzed by peptide enzyme immunoassays in order to determine the antibody reactivity against a V3 sequence based on local HIV-1 strains in Ethiopia. V3 peptides were produced according to the Ethiopian subtype C V3 consensus sequence (RKSIRIGPGQTFYAT), the HIV-1-MN and HIV-1-IIIB strains (subtype B), and the consensus sequences of subtypes A, D, and E. Initial analyses showed that Ethiopian anti-V3 positive sera cross-reacted between subtype A and subtype C peptides, and displayed much lower reactivities to the other peptides. Using inhibition experiments, it was found that the reactivities in the Ethiopian samples were specific for subtype C. Antibody reactivity to Ethiopian consensus V3 peptide was found in 96% of the Ethiopian patients. A strong reactivity to the Ethiopian V3 consensus sequence was found in 59% of the Ethiopian samples, independent of geographical origin or year of sampling (1988, 54%; 1993, 60%). In 38% of the 30 Swedish HIV-1-MN positive sera, the high reactivities were restricted to the subtype B HIV-1-MN peptide. As a control, 440 of the sera were screened against the other 5 subtypes, and the number of reactions were as follows: subtype A consensus 302 (69%), B HIV-1-IIIB strain 72 (16%), D consensus 88 (42%), D of HIV-1-ELI strain 50 (11%), and E consensus 116 (26%). A low prevalence (10%) of strong reactivity to the HIV-1MN V3 peptide was found among the Ethiopian samples. The significant ( 50% decrease in optical density value) inhibition of antibody reactivity to the Ethiopian consensus V3 peptide and to the HIV-1-MN V3 peptide, respectively, showed a high specificity of the peptides. Substitution peptide analogs demonstrated that a lack of cross-reactivity between subtype B and C peptides was dependent on the Arg-322 to Gln-322 substitution. A similar antibody recognition pattern was present in sera sampled during 1993 as in sera sampled during 1988, suggesting that subtype C of HIV-1 has remained the dominant subtype in Ethiopia.