Habitat, species richness and hantaviruses of sigmodontine rodents within the Interior Atlantic Forest, Paraguay

<div><p>Four of the nine sigmodontine tribes have species that serve as reservoirs of rodent-borne hantaviruses (RBO-HV), few have been studied in any depth. Several viruses have been associated with human cases of hantavirus pulmonary syndrome often through peridomestic exposure. Jabora (JABV) and Juquitiba (JUQV), harbored by <i>Akodon montensis</i> and <i>Oligoryzomys nigripes</i>, respectively, are endemic and sympatric in the Reserva Natural de Bosque Mbaracayú (RNBM), Paraguay, a protected area of the Interior Atlantic Forest. Rodent communities were surveyed along a 30 km stretch of the RNBM in eight vegetation classifications (Low, High, Bamboo, Riparian and Liana Forests, Bamboo Understory, Cerrado, and Meadow/Grasslands). We collected 417 rodents from which 11 species were identified; <i>Akodon montensis</i> was the predominant species (72%; 95%CI: 64.7%-76.3%), followed by <i>Hylaeamys megacephalus</i> (15% (11.2%-18.2%)) and <i>Oligoryzomys nigripes</i> (9% (6.6%-12.4%)). We examined the statistical associations among habitat (vegetation class) type, rodent species diversity, population structure (age, sex, and weight), and prevalence of RBO-HV antibody and/or viral RNA (Ab/RNA) or characteristic <i>Leishmania</i> tail lesions. Ab/RNA positive rodents were not observed in Cerrado and Low Forest. <i>A</i>. <i>montensis</i> had an overall Ab/RNA prevalence of 7.7% (4.9%-11.3%) and <i>O</i>. <i>nigripes</i> had an overall prevalence of 8.6% (1.8%-23.1%). For <i>A</i>. <i>montensis</i>, the odds of being Ab/RNA positive in High Forest was 3.73 times of the other habitats combined. There was no significant difference among age classes in the proportion of Ab/RNA positive rodents overall (p = 0.66), however, all 11 RNA-positive individuals were adult. Sex and habitat had independent prognostic value for hantaviral Ab/RNA in the study population; age, presence of tail scar/lesion (19% of the rodents) and weight did not. Adjusting for habitat, female rodents had less risk of becoming infected. Importantly, these data suggest habitat preferences of two sympatric rodent reservoirs for two endemic hantaviruses and the importance of including habitat in models of species diversity and habitat fragmentation.</p></div

Representative photographs of lesions identified in rodents at the base of the tail.

<p>Photographs from adult, male mice are shown; TK184522 and TK 184221 are <i>Akodon montensis</i>, and TK184717 is <i>Nectomys rattus</i>. Enlarged view of lesions are shown for TK184521 and TK184717.</p

Overall hantaviral (HV) Ab/RNA status and Shannon diversity in captured rodents by line.

<p>Overall hantaviral (HV) Ab/RNA status and Shannon diversity in captured rodents by line.</p

Distribution of IFA Reciprocal titers in rodent reservoir species of JABV and JUQV.

<p>Distribution of IFA Reciprocal titers in rodent reservoir species of JABV and JUQV.</p

Univariate association of sex, age, weight, habitat and characteristic tail scar with hantaviral Ab/RNA in captured rodents.

<p>Univariate association of sex, age, weight, habitat and characteristic tail scar with hantaviral Ab/RNA in captured rodents.</p

Molecular phylogenetic analysis of S segment of sequences from <i>A</i>. <i>montensis</i> and <i>O</i>. <i>nigripes</i>.

<p>Sequences from rodent lung specimens TK121843 TK184699, TK121861, TK184686 and TK184709 and GenBank references were analyzed using the Maximum Likelihood method based on the General Time Reversible model [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201307#pone.0201307.ref043" target="_blank">43</a>]. Reference sequences are shown with their GenBank reference number, virus and country from which they were isolated. The tree with the highest log likelihood (-1374.9790) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then selecting the topology with superior log likelihood value. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+<i>G</i>, parameter = 0.2861)). The rate variation model allowed for some sites to be evolutionarily invariable ([+<i>I</i>], 0.0010% sites). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The analysis involved 14 nucleotide sequences. Codon positions included were 1st+2nd+3rd. There was a total of 251 positions in the final dataset. Evolutionary analyses were conducted in MEGA7.</p

<i>Akodon montensis</i> sampled in RNBM by age, sex, and Ab/RNA prevalence.

<p><i>Akodon montensis</i> sampled in RNBM by age, sex, and Ab/RNA prevalence.</p

Multivariable logistic regression modeling identified sex and habitat as independent prognostic factor of hantaviral Ab/RNA prevalence in rodents.

<p>Multivariable logistic regression modeling identified sex and habitat as independent prognostic factor of hantaviral Ab/RNA prevalence in rodents.</p

Presence of hantaviral antibody (Ab) in blood and/or viral RNA in lung blood or lung by rodent species.

<p>Presence of hantaviral antibody (Ab) in blood and/or viral RNA in lung blood or lung by rodent species.</p

Study region of RNBM highlighting locations of transects and habitat type.

<p>Land cover types shown for a corridor through RNBM (inset shows an outline of the park and transect location) in which the trapping sites were located. Vegetation classes were derived from Naidoo and Hill, 2006.</p