The V3 loop of both HIV-1 and HIV-2 is characterized by a high degree of genetic variation. To investigate the spectrum of HIV-2 variability in nature we have focused on the C2V3 region of Env and analyzed 108 viral sequences obtained from uncultured peripheral blood mononuclear cells obtained from 16 HIV-2-seropositive individuals from Bissau (Guinea-Bissau). The estimated values of genetic divergence between individuals were higher than those calculated from sequence information collected in a single individual. We have also found that the sequences surrounding the V3 loop contribute significantly to the overall genetic diversity of the C2V3 region of HIV-2 gp105, while the V3 loop itself seems to be rather conserved. Phylogenetic analysis demonstrated that all the individuals enrolled in this study were infected with HIV-2 subtype A viruses.

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Sequence change dynamics in the highly polymorphic C2V3 region of the envelope glycoprotein gp105 coding sequence of HIV-2 was studied for two HIV-2 seropositive Guinean individuals over a 5-year period. Proviral DNA was amplified by PCR from uncultured peripheral blood mononuclear cells (PBMC), cloned, and sequenced. Amino acid sequence alignment and phylogenetic analysis showed distinct viral populations for the three collected samples (1992, 1995, and 1997) for both individuals. A discontinuous replacement of sequences suggests activation of latent viruses present in reservoirs, a process that has been documented for the HIV-1 infection but unreported so far for HIV-2. The nucleotide sequences presented in this work have been assigned accession numbers AJ400276 to AJ400319.

The pigeonpea is an important grain legume in various regions of the world. It is a pulse that is cultivated mainly by small farmers in semi-arid tropical regions for various purposes, including food security, livestock feed, and agroforestry systems. We examined the genetic diversity and structure of 73 pigeonpea accessions from 10 origins, including regions of Brazil, Central America, and India. Allelic diversity and polymorphism, molecular analysis of variance (AMOVA), Bayesian analysis (Structure) and a dendrogram were estimated based on data concerning 11 microsatellite loci. AMOVA revealed wide genetic differentiation among the pigeonpea populations, with F ST ranging from 0.22 to 0.25. Expected heterozygosity in the accessions was greater than the observed heterozygosity in eight of the 11 loci, with the observed heterozygosity ranging from 0.06 to 0.55. Polymorphic information content ranged from 0.13 to 0.67 among the 11 loci. Genetic similarity among pigeonpea accessions ranged from 0.26 to 0.93, indicating considerable variability among them, with the formation of three groups, one of which included all Brazilian accessions. Two groups were formed in the Structure analysis, indicating reduced allele sharing between the populations of Northeast Brazil and other populations. This information highlights the importance of incorporating germplasm from the Brazilian ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 20 (1): gmr18807 A.E da S. Costa et al. 2Northeast into pigeonpea breeding programs in Brazil, to increase the variability in germplasm collections.

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