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A specific subtype C of human immunodeficiency virus type 1 circulates in Brazil
Marcelo A Soares1, Tulio De Oliveira, Rodrigo M Brindeiro
1Laboratório de Virologia Molecular, Departamento de Genética, Universidade Federal do Rio de Janeiro, CCS - Bloco A - Cidade Universitária - Ilha do Fundão, 21944-970 Rio de Janeiro, RJ, Brazil.
Insights
Human immunodeficiency virus type 1 (HIV-1) subtype C strains in Brazil form a distinct group with unique amino acid patterns. Drug resistance mutations are emerging, potentially influenced by subtype C characteristics, impacting treatment and vaccine development.
Area of Science:
- Virology
- Molecular Epidemiology
- Infectious Diseases
Background:
- Subtype C is a major subtype of human immunodeficiency virus type 1 (HIV-1) globally.
- Understanding the genetic diversity and evolution of HIV-1 subtypes is crucial for effective control strategies.
Purpose of the Study:
- To characterize HIV-1 subtype C strains circulating in Brazil, with a focus on the southern region.
- To identify specific genetic signatures and drug resistance mutations within these strains.
Main Methods:
- Plasma viral RNA was extracted from 112 HIV-1-positive individuals.
- Protease (PR) and reverse transcriptase (RT) regions were amplified and sequenced.
- Brazilian subtype C strains were compared to global subtype C sequences to identify unique patterns.
Main Results:
- Brazilian subtype C viruses formed a distinct monophyletic group with unique amino acid signatures.
- Recombination between HIV-1 subtypes C and B was observed in areas of co-circulation.
- Primary and secondary drug resistance mutations, some specific to subtype C, were identified in treatment-naïve individuals.
Conclusions:
- The introduction of HIV-1 subtype C in Brazil likely resulted from a single introduction event.
- Ongoing recombination between subtypes C and B is occurring.
- Subtype-specific polymorphisms may influence drug resistance and impact HIV treatment and vaccine development in Brazil.
Objective:
To characterize the subtype C strains of HIV type 1 that circulate in Brazil, especially those originated from the southern part of the country.
Design And Methods:
One hundred and twelve HIV-1-positive subjects had their plasma viral RNA extracted. Protease (PR) and reverse transcriptase (RT) genomic regions were polymerase chain reaction-amplified and sequenced for subtype determination. Subtype C strains were selected and compared to other strains of this subtype from the database, and specific amino acid signature patterns were searched.
Results:
Brazilian subtype C viruses form a very strong monophyletic group when compared to subtype C viruses from other countries and presented specific signature amino acids. Recombinants between subtype C and B viruses have been documented in areas of co-circulation. The incidence of primary PR and RT inhibitor resistance mutations in drug-naïve subjects was observed. An increasing number of secondary resistance mutations was also seen, some of which are characteristic of subtype C-related sequences.
Conclusions:
Introduction of subtype C of HIV-1 in Brazil was likely a single event of one or a mixture of similarly related strains. Recombination between subtype C and B viruses is an ongoing process in the country. Primary and secondary drug resistance mutations were observed, although some of the secondary mutations could be associated with subtype C molecular signatures. Subtype-specific polymorphisms of PR and RT sequences found in this subtype C Brazilian variant might influence this emergence and have an impact on HIV treatment and on vaccine development in the country.