Microhabitat Factors Influenced the Prevalence of Pathogenic Leptospira spp. in Small Mammal Host

Leptospirosis, a widespread zoonotic disease, is a public health problem, especially in major urban centres, and is mainly reported to be associated with rats. In Malaysia, focus has been primarily given to the Leptospira prevalence in rodents per se, but there is lack of information on the microhabitat structure of the outbreak areas. We aimed to determine the diversity of small mammal species, microhabitat types, and their prevalence of pathogenic Leptospira spp. in the outbreak areas, which were categorized as urban, semi-urban, and recreational forests. Sampling involved deploying 100 to 300 live traps at each study site. Kidney samples were extracted from selected individuals, for screening of pathogenic Leptospira spp. by PCR. Out of 537 individuals from 15 small mammal species captured, 4 species were recorded from urban, 13 from semi-urban, and 11 from recreational forest sites. From 389 individuals screened, 58 were tested positive for pathogenic Leptospira. Recreational forests recorded the highest prevalence with 19.4% (n = 93), followed by urban, 16.6% (n = 163) and semi-urban sites with 9.8% (n = 133). Seven rodent species were tested positive for pathogenic Leptospira from all areas. R. norvegicus was found to harbour the highest prevalence (66.7%) in urban, R. rattus (53.8%) in semi-urban, whereby M. whiteheadi (44.4%) in recreational forest sites. Microhabitat analysis revealed that rubbish quantity contributed especially strongly to a high prevalence of Leptospira. This study contributes to understanding of the host and microhabitat preferences of Leptospira, which is important in controlling the spread of this disease in human's landscapes.

Characterization of monoclonal antibodies for identification of Borrelia japonica, isolates from Ixodes ovatus

Monoclonal antibodies for identification of Borrelia japonica isolated from tick, Ixodes ovatus and long-tailed shrew, Sorex unguiculatus in Japan and Borrelia related to Lyme disease (Borrelia burgdorferi sensu lato) were prepared and characterized. All isolates belonging to B. japonica and isolates from I. dentatus and cottontail rabbit in North America reacted with MAb O1441b against flagellin which was prepared from immunized mice with strain HO14, type strain of B. japonica, but isolates from I. persulcatus, patient, and wood mouse, Apodemus speciosus ainu, in Japan, and isolates belonging to B. burgdorferi, B. garinii and B. afzelii from North America and Europe did not. Strains used in this study reacted with MAb P62 against common antigen which was prepared from immunized mice with strain NT24 isolated from I. persulcatus in Japan, but B. japonica did not. These MAbs are useful for identification and differentiation of B. japonica and B. burgdorferi sensu lato in Japan.

[Biological characteristics, relationship between antigen and serology of tupaial adenoviruses (type I and II)]

The strains of adenovirus were isolated from pharyngeal swabs, kidney cell cultures and stool of tupaias. They were identified by a series tests of biological characteristics and electron microscopy studies. 10 strains of tupaia adenoviruses (TAV) may be divided into two serum types: termed TAV-I and TAV-II. There was no cross-reactivity of neutralization antibody between TAV-I and TAV-II, except a slight cross-reactivity in the complement fixation test. TAV-I could hemagglutinate R.B.C. of rat, mouse, human 'O' type, and tupaia itself, but TAV-II, couldn't. The positive rate of TAV-I and TAV-II antibodies in blood was more than 50% in natural tupaia population, suggesting of TAV infecting latently in wild tupaia colony.

Organotropism of latent herpes simplex virus type 1 is correlated to the presence of a 1.5 kb RNA transcript mapped within the BamHI DNA fragment B (0.738 to 0.809 map units)

The transcriptional activity of the DNA sequences within the genome of herpes simplex virus type 1 (HSV-1) at the coordinates 0.760 to 0.762 and their influence in the process of viral latency were investigated. Seven avirulent HSV-1 strains (HFEM, 1752/2, 1752/3, 1752/11, 1469, 1475, 1618), two virulent wild-type HSV-1 strains (F and 17) and three virulent intratypic HSV-1 recombinant viruses (R19, R26, RM1C1) were screened. The virulent HSV-1 strains colonize the ganglia but the avirulent virus strains are only able to persist in the spleen of infected animals (tree shrews). A 1.5 kb RNA transcript was detectable in all virus strains recovered from the ganglia. This RNA transcript hybridised to the HSV-1 DNA sequences at the genome coordinates 0.760 to 0.762 (BssHII DNA fragment F, part of the BamHI DNA fragment B of HSV-1, 0.738 to 0.809 map units (m.u.]. In contrast it was found that the 1.5 kb RNA transcript was missing or its size was changed in cells infected with those HSV-1 strains which were recovered from the spleens of latently infected animals. The state of viral latency of three defined deletion variants of HSV-1 strain 17 (1704, 1705, and 1706) whose genome harbors deletions (2.2 to 5.3 kb) comprising the DNA sequences of the particular region (0.760 to 0.762 m.u.) was investigated. These studies revealed that all three deletion variants could only be recovered from the spleens of latently infected tree shrews.

Isolation and characterization of a tupaia rhabdovirus

Liver tumor biopsies of a 9-year-old moribund Tupaia (tree shrew) were explanted and cultured in vitro. The cell cultures degenerated spontaneously. A virus was isolated from the cell-free supernatant of these cultures and subsequent electron microscopy revealed rhabdovirus-like particles. Negative staining showed typical bullet-shaped particles 125-220 nm in length with a diameter of 68 nm studded with a dense layer of surface projections 9-11 nm in length. One end of the virion was flat, the other end was open; a distinct ribonucleoprotein (RNP) core was visible. The pitch of the RNP was 4.5 nm. Virus was assembled and matured by budding primarily into regions of dilated endoplasmic reticulum. The dimensions of the virion also were determined in ultrathin sections: the diameter and length of the virion were 52 and 125-255 nm, respectively, those of the RNP core were 39 and 120-240 nm. Only tupaia embryonic fibroblasts and kidney cells were susceptible to the rhabdovirus. The virus, when plaque-assayed on tupaia embryonic fibroblasts, grew to a titer of 1 X 10(6) PFU.

Tupaia (tree shrew) adenovirus DNA: sequence of the left-hand fragment corresponding to the transforming early region of human adenoviruses

The nucleotide sequence of the left-hand region of the adenovirus DNA of the phylogenetically interesting tree shrew, (Tupaia belangeri) has been determined. Transcription signals, initiation codons, splice sites and termination codons were assigned on the basis of its relatedness to the EIA region of human adenoviruses 5, 7 and 12. A consensus sequence for encapsidation of adenoviral DNA that is based on the established packaging region of adenovirus 16 is proposed. The sequenced region includes the gene for a 18 000 dalton polypeptide that corresponds to the EIA proteins of the transforming region of the human serotypes. The deduced amino acid sequence of the 18 000 dalton TAV polypeptide contains a highly conserved central domain that is homologous to the middle of the 30 000 dalton polypeptides of human adenovirus indicating the significance of the central amino acid residues for the biological function of the EIA proteins.

The nucleotide sequence of the inverted terminal repetition of the tree shrew adenovirus DNA

The termini of the tupaia (tree shrew) adenovirus (TAV) DNA have been sequenced. The inverted terminal repetitions (ITR) are 166 bp long containing the A + T-rich, highly conserved sequence present in all adenovirus DNAs so far analysed. An unusual feature within the TAV ITR is the presence of four sets of a conserved sequence TGACCG which occur at or near the ends of many adenovirus ITR.

Tree shrew (Tupaia) herpesviruses

Five Tupaia herpesviruses have been isolated until now: four in our laboratory which were termed THV-2, 3, 4, and 5, whereas THV-1 has been isolated by Melnick and his colleagues. THV-2 was isolated from tumour cell culture of a high-grade malignant lymphoma of a Tupaia, THV-3 was released from a cell culture of another Tupaia lymphoma, THV-4 from a spleen tissue culture of a moribund animal with finely granulated liver cirrhosis, and THV-5 from cultured spleen cells of an apparently healthy tree shrew. THV-1 to 5 were efficiently propagated, plaque-purified and cloned on Tupaia embryonic fibroblasts. The five isolates of Tupaia herpesviruses are easily distinguished from each other by restriction enzyme analysis of their genomes. THV-1 to 4 are highly pathogenic (lethality 100%) for juvenile Tupaias by intravenous inoculation. In contrast, only 25% lethality was found by intraperitoneal administration. THV-1 to 4 can persist as a latent infection in spleens of Tupaias and rabbits, which allows the recovery of infectious virus from cultured spleens of both animals. THV-2 and 3 induced hyperplasia of the thymus of rabbits which developed malignant thymoma in a few cases. The biological properties and genomic size and structure indicate that THV cannot be considered to belong to one of the three existing subfamilies of herpesviruses.

Analysis of polypeptides of the tree shrew (Tupaia) herpesvirus by gel electrophoresis

The virion polypeptide composition of three independently isolated tree shrew herpesviruses (THV) was analysed by SDS-polyacrylamide slab gel electrophoresis and by a two-dimensional technique using isoelectric focusing. Two of the virus isolates analysed were from malignant tumours; the other isolate (THV, strain 1) was from an apparently healthy animal. The polypeptide patterns of the three purified Tupaia herpesvirus isolates were remarkably similar, each consisting of at least 35 polypeptides ranging in mol. wt. from 12,000 to 230,000. Whilst the majority of analogous polypeptides of the three viruses were of indistinguishable electrophoretic mobility, some (e.g. polypeptides of 82K to 86K) showed small differences in apparent mol. wt. which were characteristic of the virus strain. Comparative SDS-polyacrylamide gel electrophoresis made it possible to distinguish the Tupaia herpesvirus isolates from each other. At least five glycoproteins were found in purified THV virions. The two-dimensional electropherograms revealed at least 47 discernible protein spots, some of which were specific for a given THV isolate and which were detectable even in lysates of THV-infected cells.

Experimental infection and the state of viral latency of adult tupaia with herpes simplex virus type 1 and 2 and infection of juvenile Tupaia with temperature-sensitive mutants of HSV Type 2

The susceptibility of adult Tupaia Belangeri to infection with herpes simplex virus (HVS) was investigated. Adult animals were inoculated intraperitoneally with HSV type 1 or 2. With the exception of HSV-2, strain HG-52, 10(5)--10(6) PFU of all HSV strains caused lethal infection irrespective of the age of the animals. Infections HSV was recovered from the spinal cord of those animals which had survived infection with a low dose of virus. The DNA of the recovered viruses was compared to the DNA of the inoculated HSV. The viral genome of the recovered HSV was unchanged as judged by analysis of the fragment pattern of the viral DNA's using restriction endonucleases. Animals which had survived the first HSV infection were protected against a second infection even at highly lethal doses of HSV-1 or 2. Juvenile Tupaia survived infection with temperature-sensitive mutants of HSV-2, strain HG-52, which induced protection against a second infection with lethal doses of HSV-1 or 2.