Multiple-locus variable-number tandem repeat analysis of Leptospira interrogans and Leptospira borgpetersenii isolated from small feral and wild mammals in East Asia.

Leptospira spp. are the causative agents of a worldwide zoonosis, leptospirosis, maintained by various mammals. Each Leptospira serovar is frequently associated with a particular maintenance host, and recently, Leptospira genotype-host association has also been suggested to limit serovars to restricted areas. We investigated the molecular characteristics of L. interrogans and L. borgpetersenii which were isolated from small feral and wild animals in four East Asian states using multiple-locus variable-number tandem repeat analysis (MLVA). MLVA using 11 loci was performed on 110 L. interrogans serogroups from Japan (79 strains of 5 serogroups from 3 animal species), Philippines (21; 3; 2), Taiwan (7; 2; 3), and Vietnam (3; 1; 1). A MLVA method using 4 loci for L. borgpetersenii was established and performed on 52 isolates from Japan (26; 3; 7), Philippines (13; 1; 2), and Taiwan (13; 1; 3). In L. interrogans, serogroups Autumnalis and Hebdomadis appeared more genetically diverse than serogroups Bataviae, Grippotyphosa, Icterohaemorrhagiae, Pomona, or Pyrogenes. The former serogroup strains with the exception of one Hebdomadis strain were isolated from Apodemus speciosus while all the latter serogroup strains with the exception of Grippotyphosa were isolated from Rattus norvegicus. L. borgpetersenii was isolated from at least 11 animal species while L. interrogans was isolated from five species, which might suggest a wider host range for L. borgpetersenii. Broad host preference in a single genotype was also observed, which colonized not only different species of the same genera but also multiple animal genera. This study demonstrates that there may be variability in the range of genetic diversity among different Leptospira serogroups, which may be attributed to maintenance host animals and environmental factors.

Complete Genome Sequences of Low-Passage Virulent and High-Passage Avirulent Variants of Pathogenic Leptospira interrogans Serovar Manilae Strain UP-MMC-NIID, Originally Isolated from a Patient with Severe Leptospirosis, Determined Using PacBio Single-Molecule Real-Time Technology.

Here, we report the complete genome sequences of low-passage virulent and high-passage avirulent variants of pathogenic Leptospira interrogans serovar Manilae strain UP-MMC-NIID, a major causative agent of leptospirosis. While there were no major differences between the genome sequences, the levels of base modifications were higher in the avirulent variant.

Molecular and serological investigation of Leptospira and leptospirosis in dogs in Japan.

Canine leptospirosis, which is caused by infection with pathogenic Leptospira species, occurs worldwide, but information regarding the causative Leptospira serotypes and genotypes and their effects on virulence in dogs remains limited. Monitoring acute leptospirosis in dogs as sentinels can also aid in estimating the risk of human leptospirosis, particularly when the disease is rare, as it currently is in Japan. Among 283 clinically suspected cases of leptospirosis diagnosed from August 2007 to March 2011 in Japan, 83 cases were laboratory diagnosed as leptospirosis by blood culture, a rise in antibody titres in paired sera using a microscopic agglutination test (MAT) and/or DNA detection using flaB-nested PCR. The infected dogs comprised hunting dogs (31 dogs) and companion animals (50 dogs) and two unknown; 63.4 % of the infected dogs were males. The mortality rate was 53.2 %. A rise of at least fourfold in MAT titre was detected in 30 dogs whose paired serum samples were obtained, and the predominant reactive serogroup was Hebdomadis (53.3 %), followed by Australis (16.7 %) and Autumnalis (16.7 %). Leptospira interrogans was isolated from 45 dogs of the following serogroups: Australis (16), Autumnalis (six), Canicola (one), Hebdomadis (21) and Icterohaemorrhagiae (one). All of these serogroups caused lethal infections (57.1-100 %). Genetic heterogeneity was demonstrated in serogroups Australis, Autumnalis and Hebdomadis by multilocus sequence typing (MLST) and/or RFLP analysis based on PFGE. In serogroup Hebdomadis, each genotype determined by MLST had a unique mortality rate in the infected dogs. Although classic canine leptospirosis is associated with serovars Canicola and Icterohaemorrhagiae, serogroup Hebdomadis has become the predominant serogroup causing high mortality in Japan. This study suggests that the virulence of members of serogroup Hebdomadis in dogs may be associated with the genotypes in this serogroup.

Detection and phylogenetic analysis of hepatitis E viruses from mongooses in Okinawa, Japan.

Hepatitis E virus (HEV) infection has previously been reported in wild mongooses on Okinawa Island; to date however, only one HEV RNA sequence has been identified in a mongoose. Hence, this study was performed to detect HEV RNA in 209 wild mongooses on Okinawa Island. Six (2.9%) samples tested positive for HEV RNA. Phylogenetic analysis revealed that 6 HEV RNAs belonged to genotype 3 and were classified into groups A and B. In group B, mongoose-derived HEV sequences were very similar to mongoose HEV previously detected on Okinawa Island, as well as to those of a pig. This investigation emphasized the possibility that the mongoose is a reservoir animal for HEV on Okinawa Island.

Molecular epidemiology of human metapneumovirus from 2009 to 2011 in Okinawa, Japan.

To clarify the molecular epidemiology of human metapneumovirus (HMPV) in Okinawa Prefecture, located in a subtropical region of Japan, we performed genetic analysis of the F gene in HMPV from patients with acute respiratory infection from January 2009 to December 2011. HMPV was detected in 18 of 485 throat swabs (3.7%). Phylogenetic analysis showed that 17 strains belonged to subgroup A2 and 1 strain belonged to subgroup B1. We did not observe seasonal prevalence of HMPV during the investigation period. A high level of sequence identity was observed in the strains belonging to subgroup A2 (>95%), and no amino acid substitution was found compared with other strains detected in Japan and other countries. The pairwise distance values among the present strains belonging to subgroup A2 were short. Our results suggest that the predominant HMPV strains belonging to A2 are highly homologous and seasonal epidemics were not seen in Okinawa during the investigation period.

Survey of Japanese encephalitis virus in pigs on Miyako, Ishigaki, Kume, and Yonaguni Islands in Okinawa, Japan.

Serum specimens were collected from 125 pigs on Miyako Island, 112 pigs on Ishigaki Island, and 42 pigs on Kume Island from 2005 to 2007, and 54 pigs on Yonaguni Island from 2006 to 2007. Their sera were tested for Japanese encephalitis virus (JEV) antibody by hemagglutination inhibition (HI) assay. Five serum samples (4.5%) from Ishigaki Island were positive for HI antibody, and 4 of the 5 samples were positive for 2-mercaptoethanol- sensitive antibody (IgM Ab). All samples from Miyako, Kume, and Yonaguni Islands were negative for HI antibody. Our results indicate that JEV transmission activity was extremely low on Miyako, Ishigaki, Kume, and Yonaguni Islands. The JEV genome (JEV-RNA) was detected from the sera of one pig on Ishigaki Island. The partial gene of the E region (151 nt) was analyzed phylogenetically. The analysis showed that the new JEV-RNA belonged to genotype 3 and was closely related to JEV strains isolated in Taiwan from 1985 to 1996. It was suggested that JEV previously introduced from Taiwan had been maintained on Ishigaki Island.

Epidemiologic study of influenza infection in Okinawa, Japan, from 2001 to 2007: changing patterns of seasonality and prevalence of amantadine-resistant influenza A virus.

To clarify seasonal influenza patterns and the prevalence of amantadine-resistant influenza A viruses in Okinawa, located at the southern extremity of Japan in a subtropical climate, we conducted a laboratory-based study of influenza virus infections from 2001 to 2007. The annual outbreaks tended to show two peaks in Okinawa, in summer and winter, although the main islands of Japan, located in a temperate climate area, showed only winter influenza activity. Epidemic types and subtypes in Okinawa mostly matched those on the main islands of Japan in winter and those in Taiwan in summer. Rates of amantadine resistance dramatically increased, from 7.3% in the November 2002-to-March 2003 season to 90.0% in summer 2005, and a similarly high rate of resistance continued for the rest of the study period. Phylogenetic analysis of the hemagglutinin gene of A/H3N2 isolates collected from 2002 to 2007 revealed a monophyletic lineage that was divided into four period groups. Each group included amantadine-sensitive and -resistant viruses within independent clusters. In the November 2005-to-March 2006 season, all of the amantadine-resistant viruses were clustered in clade N, with dual (position 193 and 225) amino acid mutations in their HA1 subunits. In 2005, clade N amantadine-resistant viruses existed in Okinawa several months before the circulation of this clade on the main islands of Japan. In conclusion, surveillance in Okinawa to monitor influenza virus circulation is important for elucidating the dynamics of virus transmission in a border area between temperate and subtropical areas, as Okinawa is one of the best sentinel points in Japan.