Cornelio Sánchez-Hernández

Genetic diversity of hantaviruses in Mexico: identification of three novel hantaviruses from Neotominae rodents.

A variety of hantaviruses are harbored by rodents in North and South America, some of which can cause hantavirus pulmonary syndrome. To obtain greater evolutionary insight into hantaviruses in the Americas, a total of 211 rodents were captured in the Mexican states of Guerrero and Morelos in 2006. Anti-hantavirus antibodies were detected in 27 of 211 serum samples (12.8%) by ELISA. The distribution of seropositive rodents was: 17 Peromyscus beatae, 1 Megadontomys thomasi, 1 Neotoma picta, 6 Reithrodontomys sumichrasti, and 2 Reithrodontomys megalotis. The hantavirus small (S), medium (M), and large (L) genome segments from P. beatae, R. sumichrasti, and R. megalotis were amplified and the sequences covering the open reading frames were determined. The hantaviruses from P. beatae, R. sumichrasti, and R. megalotis were provisionally designated Montano (MTN), Carrizal (CAR), and Huitzilac (HUI), respectively. The M segment amino acid identities among the Mexican hantaviruses were 80.8-93.0%. When these M segments were compared to those of known hantaviruses, MTN virus was most closely related to Limestone Canyon (LSC) virus (88.9% amino acid identity), while the CAR and HUI viruses were most closely related to El Moro Canyon (ELMC) virus (90-91% identity). Phylogenetic analysis revealed that the MTN, CAR, and HUI viruses occupy a monophyletic clade with the LSC, ELMC, and Rio Segundo viruses, which are harbored by Peromyscus boylii, R. megalotis, and Reithrodontomys mexicanus, respectively. The data obtained in this study provide important information for understanding the evolution of hantaviruses in the Americas.

CHROMOSOMAL EVOLUTION IN GEOMYS AS REVEALED BY G- AND C-BAND ANALYSIS

We examined G- and C-banded karyotypes of five species of Geomys (G. tropicalis, G. pinetis, G. personatus, G. breviceps, G. bursarius) and three cytotypes of G. bursarius (G. b. lutescens, G. b. major, and G. b. knoxjonesi). Our results indicate extensive euchromatic and heterochromatic variation in this genus, in excess of what was predicted by nondifferentially- stained karyotypes. All the taxa of Geomys examined had heterochromatin on numerous chromosomes, in addition to the usual pericentric heterochromatin observed in mammals. Although the quality of our G-bands did not permit elucidation of all euchromatic changes, it is clear from the data that euchromatic rearrangements in this genus were extensive and included both Robertsonian and non-Robertsonian rearrangements.

NEW SPECIES OF STURNIRA (CHIROPTERA: PHYLLOSTOMIDAE) FROM NORTHERN SOUTH AMERICA

Abstract Yellow-shouldered bats (genus Sturnira Gray, 1842), found throughout Latin America, are not well understood taxonomically. Four specimens of Sturnira from Bolivia and Venezuela possess dental characteristics differing from those of currently known species, leading us to regard them as representing a new species. We describe external, dental, and cranial characteristics and conduct a multivariate comparison using 29 morphometric characters for 44 male specimens of Sturnira erythromos, S. ludovici, S. hondurensis, and the new species. In a principal components analysis, most of the variation was summarized on component I (78.5% of total character variance), a general size vector. A multiple-comparisons test of component I projections showed all differences among species pairs to be highly significant, except that between S. ludovici and S. hondurensis. For the 29 individual characters, the new species was statistically different from S. erythromos in 21, S. ludovici in 13, and S. hondurensis in 14. The new species has a unique combination of dental characteristics, including bicuspid upper incisors, trilobed lower incisors, and smooth 1st and 2nd lower molars.

Flight speeds of four species of Neotropical bats

Abstract Flight speeds of Davys naked-backed bat (Pteronotus davyi), Wagners mustached bat (P. personatus), Parnells mustached bat (P. parnellii), and Peters leaf-chinned bat (Mormoops megalophylla) were studied in Colima, Mexico, during January 2000. Bats were assessed in a simulated cave passage cleared in a dense thorn forest. Rates of travel over a known distance were measured using stopwatches. Individual flight speeds varied from 7.4 (female P. davyi) to 30.6 km/h (male M. megalophylla); mean flight speeds ranged from 11.3 (male P. davyi) to 19.1 km/h (female P. parnellii). There was a positive correlation between mean forearm length and mean flight speed. Larger bats flew faster than smaller ones. Results of this investigation provide the first report of flight speed for female P. davyi (13.1 km/h) and extend our knowledge concerning the flight speeds of other taxa studied.

Demographic features and habitat preferences of southern pygmy mice (Baiomys musculus) in Colima, Mexico

In Colima, Mexico, we conducted 8-night mark-recapture grid studies of southern pygmy mice (Baiomys mus- culus (Merriam, 1892)) in January 2003-2007 in dry deciduous and tropical moist forests. For 40 000 trap-nights, 436 indi- viduals were captured 764 times (comprising 18.6% of small mammals). The male:female ratio was 1:1.37, 82.9% were adults, 51.4% of females were pregnant or lactating, and coastal animals, on average, were heavier than those inland. Fe- males moved farther than males. Baiomys was on 17 of 25 grids (densities 1.82-106.24 individuals/ha). Moon illumination did not affect capture or recapture probabilities, but trap-night did (overall, probability increased 1.66%/night). Grids with Baiomys had less bare ground and a more open canopy. Capture sites had more grass, less dead wood and bare ground, a more open and lower canopy, and greater distance to trees. Logistic regression indicated coastal capture sites had more forbs, grasses, and woody plants, and thicker vegetation at 1 m height with trees being relatively distant. Variables differed somewhat for northern sites, and the equation for all grids included 10 of 14 environmental variables. Baiomys frequented edge of an unimproved road traversing one grid. Baiomys musculus, widespread in Colima, exhibited preference for habi- tats with relatively dense ground cover and at least a partially open canopy.

The N-terminus of the Montano virus nucleocapsid protein possesses broadly cross-reactive conformation-dependent epitopes conserved in rodent-borne hantaviruses

The hantavirus nucleocapsid (N) protein is an important immunogen that stimulates a strong and cross-reactive immune response in humans and rodents. A large proportion of the response to N protein has been found to target its N-terminus. However, the exact nature of this bias towards the N-terminus is not yet fully understood. We characterized six monoclonal antibodies (mAbs) against the N protein of Montano virus (MTNV), a Mexican hantavirus. Five of these mAbs recognized eight American hantaviruses and six European and Asian hantaviruses, but not the Soricomorpha-borne Thottapalayam hantavirus. The N protein-reactive binding regions of the five mAbs were mapped to discontinuous epitopes within the N-terminal 13-51 amino acid residues, while a single serotype-specific mAb was mapped to residues 1-25 and 49-75. Our findings suggest that discontinuous epitopes at the N-terminus are conserved, at least in rodent-borne hantaviruses, and that they contribute considerably to N protein cross-reactivity.

Flight speeds of three species of Neotropical bats: Glossophaga soricina, Natalus stramineus, and Carollia subrufa

ABSTRACT Flight speeds of Pallass long-tongued bat (Glossophaga soricina), the Mexican funnel-eared bat (Natalus stramineus), and the gray short-tailed bat (Carollia subrufa) were measured in Colima, Mexico, during January 2006. Bats from an abandoned mine tunnel were transported to a nearby simulated flyway, where speeds were determined over a known distance. For G. soricina, average speeds for 26 males and 14 females were 4.85 and 4.80 m/s, respectively (P > 0.05), which are similar to those reported by other investigators. Averages for N. stramineus were 2.84 m/s for 40 males and 2.39 m/s for 23 females, values that were statistically different (P < 0.05) despite the fact that body masses for the sexes were similar. For C. subrufa, three males and three females averaged 3.67 and 3.52 m/s, respectively. Speeds were unrelated to body mass for any of the species. Speeds for N. stramineus and C. subrufa are the first reported, whereas those for G. soricina are the first recorded under near-field conditions.

Demographic Features and Habitat Preferences of Osgoodomys banderanus (Osgood's Deermouse) in Colima, Mexico

Abstract Osgoodomys banderanus (Osgoods deermouse) was studied in January 2006 and 2007 in north-central Colima, Mexico. During 8 nights each year, five mark-recapture grids were established with elevated and ground traps. For 16,000 trap-nights, 123 individuals were captured 385 times (comprising 9.4% of captures on grids); one-third of captures were in elevated traps. The ratio of males to females was 1.51:1 (significantly different from 1:1). No sexual dimorphism in mass was detected, 84.4% were adults, and 41.5% of adult females were pregnant or lactating. Average distance between successive captures was 19.62 m, and average distance from a central point of capture was 12.74 m. Osgoodomys banderanus was captured on 6 of 10 grids (densities 0.76–30.55 individuals/ha). Probability of capture or recapture was influenced by trapping night, with probabilities peaking on nights 6 and 7. Habitat preferences were based on 14 environmental variables taken at each trapping station. Logistic regression indicated O. banderanus preferred higher canopies, closer trees, more rocks, and less grass; a model developed with nonparametric multiplicative regression consisted of the first three of these variables. Osgoodomys banderanus exhibited strong preferences for rocky areas with less dense ground cover, a more open understory, and a tall canopy. Resumen Osgoodomys banderanus (ratón de Osgood) fue estudiado en enero de 2006 y 2007 en la zona centro-norte de Colima, México, durante ocho noches por cada año en un estudio de captura y recaptura en cuadrantes. Cada año se establecieron cinco cuadrantes con trampas arbóreas y sobre el suelo. Para 16,000 trampas-noches, 123 individuos fueron capturados 385 veces (que corresponde a 9.4% de las capturas en los cuadrantes) y una tercera parte de las capturas fueron en trampas arbóreas. La proporción macho-hembra fue 1.51:1 (significativamente diferente de 1:1). No se encontró dimorfismo sexual en peso, 84.4% fueron adultos, y 41.5% de las hembras adultas estaban preñadas o lactando. La distancia promedio entre capturas sucesivas fue de 19.62 m, y la distancia promedio desde un punto central de captura fue de 12.74 m. Osgoodomys banderanus fue capturado en 6 de 10 cuadrantes con densidades de 0.76–30.55 individuos/ha. La probabilidad de captura o recaptura fue influenciada por trampa-noche, con la mayor probabilidad entre la 6a. y 7a. noche. Preferencias de hábitat se evaluaron usando medidas de 14 variables ambientales registradas en cada estación de trampeo. Regresión logística indicó que sitios frecuentados por O. banderanus tuvieron el dosel más alto, árboles más cercanos, más rocas y menos pastos; un modelo desarrollado con regresión multiplicativa no paramétrica consistió de las tres primeras variables. Osgoodomys banderanus mostró una fuerte preferencia por áreas rocosas con menor densidad en la cobertura del suelo y con un sotobosque más abierto y dosel alto.

Ecology of hantaviruses in Mexico: Genetic identification of rodent host species and spillover infection

In our recent epidemiological survey conducted in Mexico for hantavirus infection, we identified three distinct viruses circulating in Mexican wild rodents, namely Montano virus (MTNV), Huitzilac virus (HUIV), and Carrizal virus (CARV). To gain a detailed understanding of hantavirus epidemiology and its associated hosts, 410 rodents were captured at eight collecting points in Morelos and Guerrero, Mexico, and examined for hantavirus seroprevalence, the presence of viral RNA, and rodent host species identification using cytochrome b gene sequences. Of the 32 species captured, seven species were positive for hantavirus: Peromyscus beatae (31/127; 24.4%), Reithrodontomys sumichrasti (6/15; 40%), Reithrodontomys megalotis (2/25; 8%), Peromyscus aztecus evides (1/1; 100%), Peromyscus megalops (1/41; 2.4%), Megadontomys thomasi (1/9; 11.1%), and Neotoma picta (1/6; 16.7%), with an overall prevalence of 10.5%; virus genome persisted in the majority of seropositive rodents. Nucleotide sequence and phylogenetic analysis showed that the viruses belonged mainly to the three lineages previously identified. The data showed that MTNV and CARV were primarily carried by P. beatae and R. sumichrasti, respectively. In addition, the data revealed an apparent complex interaction between hantaviruses and their hosts, suggesting active transmission and/or spillover infections within sympatric rodent species.

Peromyscus perfulvus (Rodentia: Cricetidae)

Abstract Peromyscus perfulvus Osgood, 1945, is a medium-sized rodent with the English name of tawny deermouse. It is 1 of 56 species in the genus Peromyscus and has upperparts of bright cinnamon rufous along with creamy white underparts. This Mexican endemic is distributed from coastal lowlands of Jalisco and Colima to the interior of Michoacan, northernmost Guerrero, and the southwestern corner of the state of Mexico. The species is highly arboreal and inhabits tropical deciduous forest, semideciduous forest, and thorn scrub. Given its small geographic range coupled with microhabitat preferences and the fact that relevant habitats increasingly have been altered, P. perfulvus should be considered to be of conservation concern.