Surveillance for Nipah virus (NV) was conducted in Thailand's bat population. Immunoglobulin G antibodies to NV were detected with enzyme immunoassay in 82 of 1,304 bats. NV RNA was found in bat saliva and urine. These data suggest the persistence of NV infection in Thai bats.

BackgroundUnlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other amniotes, we constructed a chromosome map of the Siamese cobra (Naja kaouthia) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other amniotes.ResultsWe produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)n and six microsatellite repeat motifs ((AAGG)8, (AGAT)8, (AAAC)8, (ACAG)8, (AATC)8, and (AAAAT)6) were observed on NKAW, and most of these were also found on other amniote sex chromosomes.ConclusionsThe frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among amniote sex chromosomes.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5293-6) contains supplementary material, which is available to authorized users.

These results provide comparative hematologic data and a guide for identification of blood cells in wild-caught and captive-bred king cobra snakes. Hepatozoon infection was relatively common, but was not associated with severe hematologic abnormalities.

BackgroundThe monocled cobra (Naja kaouthia) is a medically important venomous snake in Southeast Asia. Its venom has been shown to vary geographically in relation to venom composition and neurotoxic activity, indicating vast diversity of the toxin genes within the species. To investigate the polygenic trait of the venom and its locale-specific variation, we profiled and compared the venom gland transcriptomes of N. kaouthia from Malaysia (NK-M) and Thailand (NK-T) applying next-generation sequencing (NGS) technology.MethodsThe transcriptomes were sequenced on the Illumina HiSeq platform, assembled and followed by transcript clustering and annotations for gene expression and function. Pairwise or multiple sequence alignments were conducted on the toxin genes expressed. Substitution rates were studied for the major toxins co-expressed in NK-M and NK-T.Results and discussionThe toxin transcripts showed high redundancy (41–82% of the total mRNA expression) and comprised 23 gene families expressed in NK-M and NK-T, respectively (22 gene families were co-expressed). Among the venom genes, three-finger toxins (3FTxs) predominated in the expression, with multiple sequences noted. Comparative analysis and selection study revealed that 3FTxs are genetically conserved between the geographical specimens whilst demonstrating distinct differential expression patterns, implying gene up-regulation for selected principal toxins, or alternatively, enhanced transcript degradation or lack of transcription of certain traits. One of the striking features that elucidates the inter-geographical venom variation is the up-regulation of α-neurotoxins (constitutes ∼80.0% of toxin’s fragments per kilobase of exon model per million mapped reads (FPKM)), particularly the long-chain α-elapitoxin-Nk2a (48.3%) in NK-T but only 1.7% was noted in NK-M. Instead, short neurotoxin isoforms were up-regulated in NK-M (46.4%). Another distinct transcriptional pattern observed is the exclusively and abundantly expressed cytotoxin CTX-3 in NK-T. The findings suggested correlation with the geographical variation in proteome and toxicity of the venom, and support the call for optimising antivenom production and use in the region. Besides, the current study uncovered full and partial sequences of numerous toxin genes from N. kaouthia which have not been reported hitherto; these include N. kaouthia-specific l-amino acid oxidase (LAAO), snake venom serine protease (SVSP), cystatin, acetylcholinesterase (AChE), hyaluronidase (HYA), waprin, phospholipase B (PLB), aminopeptidase (AP), neprilysin, etc. Taken together, the findings further enrich the snake toxin database and provide deeper insights into the genetic diversity of cobra venom toxins.

ABSTRACT. DNA barcodes of mitochondrial COI and Cytb genes were constructed from 54 specimens of 16 species for species identification. Intra-and interspecific sequence divergence of the COI gene (10 times) was greater than that of the Cytb gene (4 times), which suggests that the (2015) former gene may be a better marker than the latter for species delimitation in snakes. The COI barcode cut-off scores differed by more than 3% between most species, and the minimum interspecific divergence was greater than the maximum intraspecific divergence. Clustering analysis indicated that most species fell into monophyletic clades. These results suggest that these species could be reliably differentiated using COI DNA barcodes. Moreover, a novel species-specific multiplex PCR assay was developed to distinguish between Naja spp, Ophiophagus hannah, Trimeresurus spp, Hydrophiinae, Daboia siamensis, Bungarus fasciatus, and Calloselasma rhodostoma. Antivenom for these species is produced and kept by the Thai Red Cross for clinical use. Our novel PCR assay could easily be applied to venom and saliva samples and could be used effectively for the rapid and accurate identification of species during forensic work, conservation study, and medical research.

To better understand PBI-DdeI satellite DNA located in the centromeric region of python, molecular evolution analysis was conducted on 40 snake species. A ladder-like pattern of DNA bands with repetition of the 194–210 bp monomer was observed in 15 species using PCR. Molecular cloning was performed to obtain 97 AT-rich monomer sequences. Phylogenetic and network analyses showed three PBI-DdeI subfamilies with sequences grouped in species-specific clusters, suggesting rapid evolution. Slow evolution was found in eight species with shared PBI-DdeI sequences, suggesting recent species diversification, allowing PBI-DdeI no time to diverge, with limited homogenization and fixation processes. Quantitative real-time PCR showed large differences in copy number between Python bivittatus and other snakes, consistent with repeat scanning of whole genome sequences. Copy numbers were significantly higher in female Naja kaouthia than in males, concurring with chromosomal distribution of PBI-DdeI specifically localized to female W chromosomes. PBI-DdeI might act as an evolutionary driver with several repeats to promote W chromosome differentiation and heterochromatinization in N. kaouthia. Analysis revealed PBI-DdeI with a reduced copy number, compared to P. bivittatus, in most snakes studied, and it is possible that it subsequently dispersed and amplified on W chromosomes with different functional roles in N. kaouthia.

No abstract

No abstract