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

Abstract

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.

Introduction

Hantaviruses, which comprise the genus Hantavirus in the family Bunyaviridae, contain a three-segment negative-sense RNA genome. Small (S), medium (M), and large (L) RNA segments encode the nucleocapsid protein (N), glycoproteins (Gn and Gc), and an RNA-dependent RNA polymerase, respectively (Schmaljohn et al., 1986). Hantaviruses are carried by a variety of rodents and soricomorph species in nature and persistently infect their natural hosts (Jonsson et al., 2010, Song et al., 2007). Some rodent-borne hantaviruses cause hantavirus infections in humans, including hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) (Peters et al., 1999, Schmaljohn and Hjelle, 1997). HFRS, which is characterized by a high fever, hemorrhage, and renal dysfunction with a fatality rate <10%, is distributed throughout Europe, Russia, China, and Korea. HPS, which is characterized by a high fever, pulmonary dysfunction, and cardiac shock and has a ∼40% fatality rate (Peters and Khan, 2002), is distributed in North and South Americas. Humans acquire the infection primarily by the inhalation of virus-containing rodent excreta or by the bite of infected animals (Lee and Johnson, 1982). An important characteristic of hantavirus is the close relationship between the virus and its rodent host species, and co-evolution between them may have occurred on a geological timescale (Plyusnin and Morzunov, 2001).

Since the identification of HPS in the United States of America, patients have been reported from various countries in both North and South America; more than 30 hantaviruses have been identified on the American continents (Jonsson et al., 2010, Mills et al., 2010), some of which are associated with HPS. In North America, the Sin Nombre (SN), New York (NY), Monongahela, Black Creek Canal (BCC), Bayou (BAY) viruses cause HPS and are carried by Peromyscus maniculatus, Peromyscus leucopus, Peromyscus leucopus nubiterrae, Sigmodon hispidus, Oryzomys palustis, and S. hispidus, respectively (Morzunov et al., 1995, Nichol et al., 1993, Ravkov et al., 1995, Rawlings et al., 1996, Song et al., 1994, Torrez-Martinez and Hjelle, 1995). In South America, the Andes (AND), Bermejo, Lechiguanas, Maciel, Oran (ORN), Laguna Negra, Araraquara, and Juquitiba viruses are associated with HPS and are carried by Oligoryzomys longicaudatus, Oligoryzomys chacoensis, Oligoryzomys flavescens, Bolomys obscurus, O. longicaudatus, Calomys laucha, Bolomys lasiurus, and Oligoryzomys nigripes, respectively (Bohlman et al., 2002, Calderón et al., 1999, Chu et al., 2006, Johnson et al., 1997, Padula et al., 2002, Suzuki et al., 2004). Other hantaviruses that are not associated with human disease have been identified in various rodents in South America (Jonsson et al., 2010, Mills et al., 2010) such as Rio Mamore virus which was first identified indigenous hantavirus in this geographical region (Bharadwaj et al., 1997)

In Central America, Choclo virus, carried by Oligoryzomys fulvescens, has been identified as a cause of HPS in Panama (Vincent et al., 2000). Other viruses, including Rio Segundo (RIOS), Catacamas (CAT), and Calabazo, have been identified in Reithrodontomys mexicanus in Costa Rica, Oryzomys couesi in Honduras, and Zygodontomys brevicauda in Panama, respectively; however, their pathogenicity in humans is unknown (Hjelle et al., 1995, Milazzo et al., 2006, Vincent et al., 2000). Although there have been no reported cases of HPS, serological studies in rodents have indicated that several hantaviruses exist in Mexico (Castro-Arellano et al., 2009, Hjelle et al., 1995, Mantooth et al., 2001, Suzán et al., 2001). The first hantavirus genome detected in Mexico was that of El Moro Canyon (ELMC) virus from Reithrodontomys megalotis in 1995 (Hjelle et al., 1995). Another hantavirus, Playa de Oro (ORO) virus, identified recently in O. couesi in Western Mexico is most related genetically with the CAT, BAY, and BCC viruses (Chu et al., 2008). Because of the strong diversity among rodent species in Mexico and the specific nature of the virus–rodent relationship, more unrecognized hantaviruses likely exist. The objective of this study was to extend our knowledge of hantavirus ecology in Mexico and to increase our understanding of hantavirus evolution in the Americas.

Here we report the identification of three distinct hantaviruses, whose provisional names are Montano (MTN) virus in Peromyscus beatae, Carrizal (CAR) virus in Reithrodontomys sumichrasti, and Huitzilac (HUI) virus in R. megalotis in the southern Mexican states of Guerrero and Morelos. The nucleotide sequences of the open reading frames of the S, M, and L genome segments of the three Mexican hantaviruses were determined and a genetic analysis was performed. Our findings provide insight into the evolution of hantaviruses on the American continents.