The molecular epidemiology of HIV type 1 of men in Mexico

Prevalence of Drug Resistance Mutations in Protease, Reverse Transcriptase, and Integrase Genes of North Central Mexico HIV Isolates

This study set out to determine the frequency of antiretroviral drug resistance mutations in treatment-naive subjects of the north central Mexican state of San Luis Potosí. Mexican studies of antiretroviral drug resistance mutations have focused mainly on large metropolitan areas and border towns subjected to intense international migrations. This study set forth to describe the frequency of these mutations in a Mexican region less subjected to such migratory influences and more representative of smaller Mexican cities. Thirty-eight full-length pol sequences spanning the protease, reverse-transcriptase, and integrase-encoding regions were obtained from 42 treatment-naive human immunodeficiency virus (HIV)-infected subjects. Most exhibited subtype B homology, but CRF02_AG was also detected. Evidence of APOBEC3 hypermutation was seen in two samples. Calibrated population analysis revealed a surveillance drug resistance mutation prevalence of 4.9% for protease inhibitors, of 2.7% for nucleoside reverse transcriptase inhibitors, of 8.1% for non-nucleoside reverse transcriptase inhibitors, and an overall prevalence of 9.5%. This corresponds to an intermediate level of transmitted drug resistance according to the World Health Organization. The identification of integrase mutations suggests that transmitted drug mutations are being imported, as inhibitors targeting integrase have not been widely used in Mexico. Our results provide a greater understanding of HIV diversity in Mexico and highlight the way internal migrations allow HIV mutations and genetic features to permeate regions less subjected to international migrations. The implications of these findings will become more evident as Mexico hosts increased repatriations of migrants in the coming years.

A single early introduction of HIV-1 subtype B into Central America accounts for most current cases

Human immunodeficiency virus type 1 (HIV-1) variants show considerable geographical separation across the world, but there is limited information from Central America. We provide the first detailed investigation of the genetic diversity and molecular epidemiology of HIV-1 in six Central American countries. Phylogenetic analysis was performed on 625 HIV-1 pol gene sequences collected between 2002 and 2010 in Honduras, El Salvador, Nicaragua, Costa Rica, Panama, and Belize. Published sequences from neighboring countries (n = 57) and the rest of the world (n = 740) were included as controls. Maximum likelihood methods were used to explore phylogenetic relationships. Bayesian coalescence-based methods were used to time HIV-1 introductions. Nearly all (98.9%) Central American sequences were of subtype B. Phylogenetic analysis revealed that 437 (70%) sequences clustered within five significantly supported monophyletic clades formed essentially by Central American sequences. One clade contained 386 (62%) sequences from all six countries; the other four clades were smaller and more country specific, suggesting discrete subepidemics. The existence of one large well-supported Central American clade provides evidence that a single introduction of HIV-1 subtype B in Central America accounts for most current cases. An introduction during the early phase of the HIV-1 pandemic may explain its epidemiological success. Moreover, the smaller clades suggest a subsequent regional spread related to specific transmission networks within each country.

HIV-1 V3 loop crown epitope-focused mimotope selection by patient serum from random phage display libraries: implications for the epitope structural features

The crown region of the V3 loop in HIV-1 that contains the conserved amino acid sequence GPGR/G is known as the principal neutralizing determinant due to the extraordinary ability of antibodies to this region to neutralize the virus. To complement the existing peptide models of this epitope, we describe a family of 18 phage-displayed peptides, which include linear 12mer and constrained 7mer peptides that was selected by screening random libraries with serum from HIV-1 subtype B-infected patients. The 7mer constrained peptides presented two conserved amino acid sequences: PR-L in N-terminus and GPG in the C-terminus. On the basis of these peptides we propose a mimotope model of the V3 crown epitope in which the PR-L and GPG sequences represent the two known epitope binding sites. The GPG, has the same function as the V3 crown GPGR sequence but without the involvement of the "R" despite its being considered as the signature of the epitope in B-subtype viruses. The PR-L contains a proline not existing in the epitope that is postulated to induce kinks in the backbones of all peptides and create a spatial element mimicking the N-terminal conformationally variable binding site. Rabbit serum to these mimotopes recognized the V3 peptides and moderately decreased the fusion between HIV-1 Env- and CD4-expressing Jurkat cells. This study proposes the efficient generation by means of patient sera of V3 epitope mimics validated by interaction with the antibodies to contemporary viruses induced in patients. The serum antibody-selectable mimotopes are sources of novel information on the fine structure-function properties of HIV-1 principal neutralizing domain and candidate anti-HIV-1 immunogens.

National prevalence and trends of HIV transmitted drug resistance in Mexico

Background

Transmitted drug resistance (TDR) remains an important concern for the management of HIV infection, especially in countries that have recently scaled-up antiretroviral treatment (ART) access.

Methodology/Principal Findings

We designed a study to assess HIV diversity and transmitted drug resistance (TDR) prevalence and trends in Mexico. 1655 ART-naïve patients from 12 Mexican states were enrolled from 2005 to 2010. TDR was assessed from plasma HIV pol sequences using Stanford scores and the WHO TDR surveillance mutation list. TDR prevalence fluctuations over back-projected dates of infection were tested. HIV subtype B was highly prevalent in Mexico (99.9%). TDR prevalence (Stanford score>15) in the country for the study period was 7.4% (95% CI, 6.2∶8.8) and 6.8% (95% CI, 5.7∶8.2) based on the WHO TDR surveillance mutation list. NRTI TDR was the highest (4.2%), followed by NNRTI (2.5%) and PI (1.7%) TDR. Increasing trends for NNRTI (p = 0.0456) and PI (p = 0.0061) major TDR mutations were observed at the national level. Clustering of viruses containing minor TDR mutations was observed with some apparent transmission pairs and geographical effects.

Conclusions

TDR prevalence in Mexico remains at the intermediate level and is slightly lower than that observed in industrialized countries. Whether regional variations in TDR trends are associated with differences in antiretroviral drug usage/ART efficacy or with local features of viral evolution remains to be further addressed.

Molecular epidemiology of HIV type 1 in Mexico: emergence of BG and BF intersubtype recombinants

The molecular epidemiology of subtypes and intersubtype recombinants (IRs) of human immunodeficiency virus type 1 (HIV-1) in Mexico has not been characterized fully. Understanding its regional distribution, prevalence, adaptability, viral fitness, pathogenicity, and immunogenicity is decisive for any design of an effective HIV vaccine. The aim of this study was to describe the presence of IRs types BG and BF in a Mexican population. Protease and reverse transcriptase regions of the pol gene were sequenced using an automated sequencing system. A phylogenic tree was constructed and genetic distances were calculated using MEGA 3.1. Recombination analysis was done by bootscan using SimPlot software. Two hundred and twenty-three HIV-1-positive individuals were enrolled in the study. At baseline, the mean plasma viral load was 285,500 HIV-1 RNA copies/ml and the mean CD4 cell count was 213 cells/ml. Subtype B was found in 220 (98.6%) samples, whereas IRs were found in three patients (1.4%): two (0.9%) with BG and one (0.45%) with BF. IRs were observed in 2/124 (1.6%) samples from treated patients and in 1/99 (1.0%) from naive patients. The presence of these HIV forms at low frequency points to the need for research on the diversity, geographic distribution, and evolution of other subtypes including circulating recombinant forms and IRs to understand the molecular epidemiology and tendencies of the HIV infection in Mexico.

Molecular epidemiology of HIV type 1 in northern Brazil: identification of subtypes C and D and the introduction of CRF02_AG in the Amazon region of Brazil

The molecular epidemiology of HIV-1 strains circulating in Belem-PA and Macapa-AP, in the Northern region of Brazil, is described using sequences of the C2V3 segment of the env and the pro gene of HIV-1 from patients of the Reference Unit for Special Infectious and Parasitary Diseases (URE-DIPE) in Belem-PA and the Central Laboratory (LACEN) in Macapa-AP. Subtype B was the most frequently found in relation to pro (88.3%) in Belem and in Macapa (97.1%) and env (88.3% in Belem and 100% in Macapa). Subtype F was also described in Belem (9.3% pro and 8.3% env) and Macapa (2.8% pro). Subtype D was described for the first time in the Northern region of the country as well as the recent entry of CRF02_AG. Furthermore, several possible recombinant forms among the various subtypes were found in both cities. The results support the hypothesis that HIV-1 infection is associated with the epidemic of the virus in the Southeast region of the country and that the city of Belem is the most important route for HIV-1 entry in the Northern region of Brazil.

High divergence within the major HIV type 1 subtype B epidemic in Panama

The first molecular epidemiology study of human immunodeficiency virus type 1 (HIV-1) in Panama has been performed with plasma samples from 66 AIDS patients infected by different transmission routes and obtained from distinct locations. All samples were amplified by RT-PCR and sequenced in gag (p17) and env (C2-C4) genes. Phylogenetic analyses revealed that 64 (97%) of the samples belong to subtype B. We also identified the presence of two CRF, one CRF12_BF and one CRF02_AG. The most notable feature of the subtype B epidemic in Panama was the large genetic distance among isolates with a mean of 15.2% but reaching up to 31.3 % in env, indicating an epidemic with a long period of evolution.

First molecular surveillance report of HIV type 1 in injecting drug users and female sex workers along the U.S.-Mexico border

HIV prevalence is increasing among high-risk populations in the Mexican-U.S. border cities of Tijuana and Ciudad Juarez. In 2005, the molecular epidemiology of HIV-1 was studied among injecting drug users (IDU) and female sex workers (FSW) in these cities, which are corridors for over two-thirds of the migrant flow between Mexico and the United States. Eleven samples (eight IDU and three FSW) were successfully amplified, sequenced, and analyzed. The results revealed that all 11 samples were subtype B. There was no phylogenetic clustering or separation of the strains between IDU and FSW or between Tijuana and Ciudad Juarez nor was the Mexican strain phylogenetically distinct from other subtype B strains. Two of three drug naive FSWs had low-level HIV-1 resistance mutations. This community-based study demonstrated that HIV-positive IDUs and FSWs in Ciudad Juarez and Tijuana were predominantly infected with subtype B. Further prevalence studies on HIV-1 resistance mutations among FSWs in these border cities are warranted.