Genetic analysis of HIV-1 samples from Spain

The Characteristics of the HIV-1 Env Glycoprotein Are Linked With Viral Pathogenesis

The understanding of HIV-1 pathogenesis and clinical progression is incomplete due to the variable contribution of host, immune, and viral factors. The involvement of viral factors has been investigated in extreme clinical phenotypes from rapid progressors to long-term non-progressors (LTNPs). Among HIV-1 proteins, the envelope glycoprotein complex (Env) has been concentrated on in many studies for its important role in the immune response and in the first steps of viral replication. In this study, we analyzed the contribution of 41 Envs from 24 patients with different clinical progression rates and viral loads (VLs), LTNP-Elite Controllers (LTNP-ECs); Viremic LTNPs (vLTNPs), and non-controller individuals contemporary to LTNPs or recent, named Old and Modern progressors. We studied the Env expression, the fusion and cell-to-cell transfer capacities, as well as viral infectivity. The sequence and phylogenetic analysis of Envs were also performed. In every functional characteristic, the Envs from subjects with viral control (LTNP-ECs and vLTNPs) showed significant lower performance compared to those from the progressor individuals (Old and Modern). Regarding sequence analysis, the variable loops of the gp120 subunit of the Env (i.e., V2, V4, and mainly V5) of the progressor individuals showed longer and more glycosylated sequences than controller subjects. Therefore, HIV-1 Envs from virus of patients presenting viremic control and the non-progressor clinical phenotype showed poor viral functions and shorter sequences, whereas functional Envs were associated with virus of patients lacking virological control and with progressor clinical phenotypes. These correlations support the role of Env genotypic and phenotypic characteristics in the in vivo HIV-1 infection and pathogenesis.

Characterization and signature pattern analysis of Korean clade HIV-1 using nef gene sequences

Phylogenetic studies of the HIV-1 gene sequences isolated from Korean patients have suggested that most of Korean isolates belong to the subtype B strain. This study aims to characterize the Korean clade by molecular phylogenetic analysis using all of the Korean nef gene sequences registered in the NCBI GenBank (N=422), in addition to 41 reference strains and 94 foreign isolates. Through phylogenetic analyses, we verified that most of the Korean isolates belonged to the subtype B, where 78.8% are clustered exclusively of foreign isolates. This cluster has been named the Korean clade subtype B (KCB) in order to distinguish it from other subtype B clusters. Genetic distance analysis suggested that the KCB cluster was more homogeneous and clearly distinctive from the non-Korean clade subtype B (NKCB). Comparison of consensus amino acid sequences from KCB and NKCB revealed that characteristic KCB signature amino acid patterns composed of 11 amino acid residues, whose frequencies in the KCB were significantly higher than in the NKCB. The KCB signature amino acid residues were critical in identifying KCB from NKCB, since substitution of the NKCB sequences with KCB signature amino acids relocated them to the Koran clade, and vice versa.

A dual superinfection and recombination within HIV-1 subtype B 12 years after primoinfection

To analyze superinfection in an HIV-1-infected patient showing high-risk practices, viral quasispecies were analyzed in pol and env genes in several plasma samples. Phylogenetic analysis in the reverse transcriptase fragment in pol gene identified a single virus in the first 3 samples analyzed, but 12 years after primoinfection, 3 different viral strains were detected in the patient quasispecies. This result suggests a superinfection with 2 HIV-1 strains, one of which showed the T215Y + M184V resistance mutations. The analysis in the env gene confirmed the existence of 3 different strains in the viral population, one of them a recombinant. This study illustrates that events of superinfection and recombination contribute to the viral genetic variability observed in HIV-1-infected individuals.

Worldwide molecular epidemiology of HIV

Human immunodeficiency virus (HIV) is the worldwide disseminated causative agent of acquired immunodeficiency syndrome (AIDS). HIV is a member of the Lentivirus genus of Retroviridae family and is grouped in two types named HIV-1 and HIV-2. These viruses have a notable ability to mutate and adapt to the new conditions of human environment. A large incidence of errors at the transcriptional level results in changes on the genetic bases during the reproductive cycle. The elevated genomic variability of HIV has carried important implications for the diagnosis, treatment and prevention as well as epidemiologic investigations. The present review describes important definitions and geographical distribution of subtypes, circulating recombinant forms and other genomic variations of HIV. The present study aimed at leading students of Biomedical Sciences and public health laboratory staff guidance to general and specific knowledge about the genomic variability of the HIV.

Evolutionary history of HIV-1 subtype B and F infections in Brazil

OBJECTIVE

To reconstruct the onset date of the HIV-1 B and F epidemics in Brazil based on virus diversification over time.

DESIGN

We studied HIV-1 env V3 sequences (210 nt) with a known sampling year isolated from HIV-1 positive patients from Brazil between 1989 and 1997: 101 subtype B sequences and 41 subtype F sequences.

METHODS

HIV-1 V3 env sequences were grouped by year of collection and the relationship between the sampling years of HIV-1 sequences and their genetic distance to the reconstructed common ancestor (intra-population divergence) or to other sequences from the same year (intra-population diversity) was examined by using linear regression analysis.

RESULTS

Regression analysis of nucleotide distances, revealed a highly significant positive correlation between sampling years of subtype B and F V3 sequences and their intra-population divergence (P < 0.001) or diversity (P < 0.0001). In both subtype populations, the divergence and diversity increased at a rate of 0.5 and 0.9% per year, respectively. Considering these evolutionary rates, we estimate the onset of the subtype B and F HIV-1 epidemics in Brazil during early 1970s and early 1980s, respectively.

CONCLUSIONS

The consistent correlation between divergence and diversity of the V3 sequences with their sampling years indicates that the molecular clock is operational in the evolution of the HIV-1 in Brazil's epidemic, and show that subtypes B and F are evolving at a similar rate over time. The dating results suggest a discontinuous introduction of these subtypes in the Brazilian population.

Few mutations in the 5' leader region mediate fitness recovery of debilitated human immunodeficiency type 1 viruses

Repeated bottleneck passages of RNA viruses result in fitness losses due to the accumulation of deleterious mutations. In contrast, repeated transfers of large virus populations result in exponential fitness increases. Human immunodeficiency virus type 1 (HIV-1) manifested a drastic fitness loss after a limited number of plaque-to-plaque transfers in MT-4 cells. An analysis of the mutations associated with fitness loss in four debilitated clones revealed mutation frequencies in gag that were threefold higher than those in env. We now show an increase in the fitness of the debilitated HIV-1 clones by repeated passages of large populations. An analysis of the entire genomic nucleotide sequences of these populations showed that few mutations, from two to seven per clone, mediated fitness recovery. Eight of the 20 mutations affected coding regions, mainly by the introduction of nonsynonymous mutations (75%). However, most of the mutations accumulated during fitness recovery (12 of 20) were located in the 5' untranslated leader region of the genome, and more specifically, in the primer binding site (PBS) loop. Two of the viruses incorporated the same mutation in the primer activation signal in the PBS loop, which is critical for the tRNA3Lys-mediated initiation of reverse transcription. Moreover, 25% of the mutations observed were reversions. This fact, together with the presence of a large proportion of nonsynonymous replacements, may disclose the operation, during large population passages, of strong positive selection for optimal HIV-1 replication, which seems to be primarily affected by binding of the tRNA to the PBS and the initiation of reverse transcription.

A subset of human immunodeficiency virus type 1 long-term non-progressors is characterized by the unique presence of ancestral sequences in the viral population

Within human immunodeficiency virus type 1 (HIV-1)-infected patients, there are those who have been infected for more than 10 years with a CD4+ cell count of >500 cells microl(-1) and who remain asymptomatic without antiretroviral therapy; these patients are designated long-term non-progressors (LTNPs). In a set of 16 LTNPs, viral dating, DNA viral load, quasispecies heterogeneity and antibody (Ab) titres against gp160 and beta2 microglobulin (beta2m) were determined. Plasma viral RNA and CD4+ and CD8+ T-cell numbers were estimated in more than three samples per patient. Host genetic characteristics, such as Delta32-CCR5 genotype and human leukocyte antigen (HLA) genotype and supertypes, and clinical-epidemiological factors were evaluated. Dating of global populations and of DNA and RNA viral quasispecies identified two subsets of patients: one displaying only ancestral sequences and the other displaying predominantly modern sequences. The ancestral patients displayed a significant reduction in RNA and DNA viral loads, quasispecies heterogeneity, CD8+ cell number, anti-gp160 Ab titres and beta2m level, and they were also associated with better use of safe-sex practices and higher presence of the HLA sB58 supertype than the modern subset. Viral dating has therefore permitted the segregation of LTNPs into two subsets that show very different virological, immunological, host and clinical-epidemiological characteristics. Moreover, whereas the modern subset displayed low levels of virus replication, the ancestral group displayed not only a very limited virus replication, often to undetectable levels, but also very slow or arrested viral evolution, maintaining the close relationship of the viral population to the transmitted virus.

Long-term suppression of plasma viremia with highly active antiretroviral therapy despite virus evolution and very limited selection of drug-resistant genotypes

HIV-1 evolution and the possible emergence of mutations associated with resistance to antiretroviral inhibitors have been evaluated in a cohort of sixty-three patients successfully treated with highly active antiretroviral therapy (HAART). The patients under effective HAART were recruited in three different hospitals in Spain, and none of them had been treated (naïve) before entering this study. HIV-1 RNA levels, CD4+, and CD8+ T-cell counts were determined, and nucleotide sequences of proviral regions encoding protease and reverse transcriptase (RT) were obtained for longitudinal blood samples spanning a mean follow-up period of 88 weeks. Phylogenetic reconstructions and calculations of genetic distances among the different sequences of each patient were performed. All except one of the patients under study showed an early and sustained decrease in plasma HIV-1 RNA to levels that were below 200 copies/ml. The plasma viral decline paralleled a significant increase in the CD4+ T-lymphocyte counts. Amino acid sequence analyses revealed the occurrence of mutations associated with antiretroviral resistance in nine patients (14.3%) during HAART treatment, that in some cases could be attributed to excess G to A transitions. In six of the nine patients, the mutations conferred resistance to inhibitors administered in the treatment regime, although the mutations did not result in treatment failure. Sequence comparisons revealed viral evolution during the period of treatment in 47.5% of the patients. The results indicate successful suppression of HIV-1 under HAART for extended time periods, indistinguishable for patients in which evidence of virus evolution could or could not be documented.

Co-existence of recent and ancestral nucleotide sequences in viral quasispecies of human immunodeficiency virus type 1 patients

In human immunodeficiency virus type 1 (HIV-1) infection, the presence of divergent nucleotide sequences within a quasispecies has been associated with double infections or samples from different times or from different tissue compartments. The authors analysed HIV-1 proviral quasispecies from PBMC of three untreated Spanish patients displaying highly divergent nucleotide sequences without evidence of double infection. The origin of these nucleotide sequences was determined by phylogenetic analysis and by dating of the different groups using a genetic divergence versus sampling year plot from a set of Spanish samples. By their short genetic distance to the node of the patient's HIV-1 phylogenetic tree and by their early date of origin, close to the seroconversion time, some groups of sequences were considered ancestral. The presence within HIV-1 quasispecies of ancestral sequences, dated up to 10 years earlier than present ones, has important consequences for in vivo viral evolution, in the pathogenesis and treatment of HIV-1 infection.

Introduction of HIV type 1 non-B subtypes into Eastern Andalusia through immigration

A study of the distribution of HIV-1 subtypes in the native and immigrant populations of Eastern Andalusia (Southern Spain) was conducted to determine any changes between 1983 and 2001 and to identify antiretroviral resistance mutations in non-B subtype strains among the immigrant population. The study included 111 native patients from Eastern Andalusia: 94 infected with HIV before 1996 and 17 infected since 1996. A parallel study was conducted on 26 HIV-positive immigrants from Africa. Subtyping was done with the heteroduplex mobility assay. Resistance mutations were determined by line probe assay. A total of 137 patients were studied: 9.2% had subtype A (n = 12), 80.8% subtype B (n = 105), and 1.5% subtype C (n = 2). Among the Eastern Andalusia population infected before 1996, 10.9% had non-B subtypes, compared with 23.5% of those infected after that year. The greatest percentage of non-B subtypes (52.4%) was found among the immigrant population. Resistance mutation K70R was detected in one of the six immigrants with non-B subtype and M41L in another. There has been a slight increase in the diversity of HIV-1 subtypes in Eastern Andalusia over the past few years, possibly influenced by non-B subtypes introduced by immigrants from sub-Saharan Africa.

Different evolutionary patterns are found within human immunodeficiency virus type 1-infected patients

In order to study the evolution in vivo of human immunodeficiency virus type 1 (HIV-1) in patients with normal clinical evolution, six individuals were selected from a group of 46 patients followed for 1 to 4 years. Patients were selected not by clinical progression characteristics but on the basis of virus genetic variability, as analysed by heteroduplex mobility assay and RNase A mismatch cleavage method. Two patients displayed a homogeneous virus population, two showed very heterogeneous quasispecies and two presented two distinct variants within the virus population. Virus quasispecies were studied by nucleotide sequencing of the C2-fusion domain of the env gene. Virus evolution was approached by analysing the distribution of genetic distances, calculation of divergence and heterogeneity as well as the K(a)/K(s) ratio and by the construction of the phylogenetic trees. Three patients displayed the same tree topology, characterized by the presence of independent clades supported by high bootstrap values, whereas this pattern was not present in the other three patients. In the three patients displaying independent clades, a recombination analysis was carried out between distinct subpopulations and recombinant variants were identified. In one patient of this group, different selective pressures were detected in distinct virus clades, measured by their corresponding K(a)/K(s) ratios, revealing that different evolutionary forces are occurring at the same time within the same patient. These results show that multiple evolutionary patterns can be found in typical HIV-1-infected patients.

Polio, hepatitis B and AIDS: an integrative theory on a possible vaccine induced pandemic

The hypothesis that simian virus 40 (SV40) infected polio vaccines may be linked to the evolution of acquired immunodeficiency disorder (AIDS), and certain cancers, has been advanced. Most recently, investigators discussed the likelihood of gene-reshuffling following SV40 infection as a precursor to acquired immune dysfunction. Findings of recent SV40 infections in four children born after 1982 suggest infections were transmitted vertically along gene lines. Earlier observations proved activation of a retrovirus gene by a hepatitis B virus (HBV) protein. This paper proposes a new integrative theory on the origin of AIDS. It advances the possibility of genetic recombinations with oncogene activation by HBV involving simian viruses that likely infected polio vaccinated blood donors to the initial hepatitis B (HB) vaccine trials conducted on gay men in New York City and Ugandan Blacks in the early to mid-1970s. The socio-economic and even military ramifications associated with this politically challenging thesis are discussed.

HIV-1 genetic diversity in Galicia Spain: BG intersubtype recombinant viruses circulating among injecting drug users

BACKGROUND

The HIV-1 epidemics in Western Europe are dominated by B subtype viruses. Non-B subtype is largely restricted to individuals infected outside of Europe and to their direct contacts and is generally acquired by the heterosexual route.

METHODS

Protease and a segment of reverse transcriptase were amplified and sequenced from plasma RNA in 451 individuals from seven cities of Galicia, north-western Spain. Subtype sequence homologies were determined using the BLAST algorithm. Non-B sequences were examined by phylogenetic analysis and intersubtype recombination by bootscanning. The env V3 region was analysed in all non-B and in 38 B subtype viruses.

RESULTS

Ten different non-B genetic forms were identified in 20 (4.4%) individuals. Subtypes were concordant between pol and V3 in five viruses; 14 (70%) infections were with intersubtype recombinant viruses, and one individual had a dual B+G infection. Seven recombinant viruses were phylogenetically related to five reported recombinant forms. Three non-recombinant G and six recombinant BG viruses formed a monophyletic cluster for pol. All but three individuals with non-B infections were native Spanish. Only 6 of 16 individuals referred to sexual contacts with sub-Saharan Africans. Twelve (60%) non-B subtype infections, including all with G and BG viruses, were in injecting drug users (IDU).

CONCLUSIONS

Non-B subtype viruses were identified in 4.4%, with a high diversity of genetic forms, including 70% infections with intersubtype recombinant viruses. The majority of individuals with non-B infections were IDU, most of them without known contacts with non-European sources, and among whom BG recombinant viruses are circulating.