Phylogenetic and geographical relationships of hantavirus strains in eastern and western Paraguay

Abstract

Recently, we reported the discovery of several potential rodent reservoirs of hantaviruses in western (Holochilus chacarius) and eastern Paraguay (Akodon montensis, Oligoryzomys chacoensis, and O. nigripes). Comparisons of the hantavirus S- and M-segments amplified from these four rodents revealed significant differences from each another and from other South American hantaviruses. The ALP strain from the semiarid Chaco ecoregion clustered with Leguna Negra and Rio Mamore (LN/RM), whereas the BMJ-NEB strain from the more humid lower Chaco ecoregion formed a clade with Oran and Bermejo. The other two strains, AAI and IP37/38, were distinct from known hantaviruses. With respect to the S-segment sequence, AAI from eastern Paraguay formed a clade with ALP/LN/RM, but its M-segment clustered with Pergamino and Maciel, suggesting a possible reassortment. AAI was found in areas experiencing rapid land cover fragmentation and change within the Interior Atlantic Forest. IP37/38 did not show any strong association with any of the known hantavirus strains.

Figure 1

Phylogenetic tree based on maximum likelihood analysis of 438 and 575 nucleotides from G1 and G2, respectively. Nucleotide sequences were analyzed by maximum likelihood analysis of PAUP version 4 b10, using heuristic search option and weighting transversions four times transitions. Bootstrap values of > 50%, obtained from 1,000 replicates of the analysis, are shown at the appropriate branch points. See Table 1 for the definition of the abbreviations used to identify each sequence.

Figure 2

Phylogenetic tree based on maximum likelihood analysis of the partial S-segment. Nucleotide sequences were analyzed by maximum likelihood analysis of PAUP version 4 b10, using heuristic search option and weighting transversions four times transitions. Bootstrap values of > 50%, obtained from 1,000 replicates of the analysis, are shown at the appropriate branch points. See Table 1 for the definition of the abbreviations used to identify each sequence.

Figure 3

Distribution of hantavirus strains in Paraguay and surrounding countries. Symbols indicate viral strain occurring at each geographic location. Map also shows the distribution of viral strains relative to major South American ecoregions.