BackgroundLeishmaniasis, caused by Leishmania siamensis, is an emerging disease in Thailand. Although reported cases have been increasing, epidemiological information of the disease including host and vector aspects is not clearly known. This study was a preliminary survey of the potential vector of L. siamensis in an affected area of leishmaniasis, Trang Province, southern Thailand.MethodsThe collection of sandflies was performed around the area where a case of leishmaniasis was reported using CDC light traps. Species of sandfly were identified based on morphological characteristics according to Lewis’s key. PCR amplification and sequencing of the heat shock protein 70 gene (hsp70) was used to identify L. siamensis DNA in sandflies.ResultsA total of 146 male and female sandflies were collected in the affected areas. Of 71 female sandflies, four species were identified, i.e., Sergentomyia (Neophlebotomus) gemmea, S. (Neophlebotomus) iyengari, S. (Parrotomyia) barraudi and Phlebotomus (Anaphlebotomus) stantoni. Among these species, S. (Neophlebotomus) gemmea was the most predominant species in all areas. DNA of L. siamensis was identified in S. (Neophlebotomus) gemmea. Nucleotide sequences of PCR products using DNA extracted from S. (Neophlebotomus) gemmea showed 99.8% identity to L. siamensis.ConclusionS. (Neophlebotomus) gemmea might be a potential vector of L. siamensis in an affected area, Trang Province, southern Thailand. However further studies are needed to prove whether these sandflies can be natural vectors of leishmaniasis.

Many mosquito transmitted viruses of the genera Alphavirus and Flavivirus are human pathogens of significant concern, and there is currently no specific antiviral for any member of these two genera. This study sought to investigate the broad utility of orlistat (tetrahydrolipstatin) in reducing virus infection for several mosquito borne viruses including flaviviruses (dengue virus (DENV; nine isolates analyzed), Japanese encephalitis virus (JEV; one isolate analyzed) and Zika virus (ZIKV; 2 isolates analyzed)) as well as an alphavirus (chikungunya virus; CHIKV; 2 isolates analyzed). Three different treatment regimens were evaluated, namely pre-treatment (only), post-treatment (only) and pre-and post-treatment, and three factors were evaluated, namely level of infection, virus titer and genome copy number. Results showed that all three treatment modalities were able to significantly reduce virus titer for all viruses investigated, with the exception of three isolates of DENV in the pre-treatment only regimen. Pre-and post-treatment was more effective in reducing the level of infection and genome copy number of all viruses investigated than either pre-treatment or post-treatment alone. collectively, these results suggest orlistat has potential as a broad-spectrum agent against multiple mosquito transmitted viruses.Mosquito transmitted viruses are a significant public health problem in many tropical and sub-tropical countries, and some of the most significant human pathogens belong to the genera Flavivirus and Alphavirus 1 . The genus Flavivirus consists of 53 virus species 2 of which more than half are transmitted by mosquitoes and the majority of these have the potential to infect humans 3 . Medically important mosquito transmitted viruses in the genus Flavivirus include dengue virus (DENV), Japanese encephalitis virus (JEV), Zika virus (ZIKV) and yellow fever virus (YFV). The genus Alphavirus consists of 31 virus species 2 the majority of which are spread by mosquitoes, and medically important alphaviruses include chikungunya virus (CHIKV), Ross River virus, Semliki Forest Virus and Sindbis virus 4 .Viruses in the genera Flavivirus and Alphavirus have a number of similarities. Viruses in both genera are classified in group IV in the Baltimore classification system 5 as they possess a positive sense single stranded RNA genome. The genome sizes are approximately equivalent (flaviviruses approximately 9.2-11 kb 6 , alphaviruses approximately 9.7-12 kb 7 , but while the ten flavivirus proteins (capsid (C), pre-membrane (prM), envelope (E), NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) are encoded by a single open reading frame, the nine alphavirus proteins are encoded by two open reading frames, the first of which encodes the non-structural proteins (nsP1, nsP2, nsP3 and nsP4), while the second open reading frame encodes the structural proteins (C, E1, E2, E3), as well as a protein (6 K) of uncertain function 4 . Viruses in both genera encode a protein with RNA-dependent RNA polymerase (RdRP) activity that undertakes gen...

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BackgroundVisceral leishmaniasis (VL) caused by Leishmania siamensis is an emerging disease continuously reported in six southern provinces of Thailand. To date, the phylogenetic relationships among Leishmania isolates from Thai patients and other Leishmania species are still unclear and the taxonomic diversity needs to be established. In this study, the phylogenetic inference trees were constructed based on four genetic loci (i.e., SSU-rRNA, ITS1, hsp70, and cyt b), using DNA sequences obtained from autochthonous VL patients from southern Thailand and reference sequences of reported Leishmania isolates from other studies deposited in GenBank.ResultsPhylogenetic analyses of hsp70 and cyt b loci supported a clade comprised of L. siamensis isolates, which is independent to the other members in the genus Leishmania. In combination with genetic distance analysis, sequence polymorphisms were observed among L. siamensis isolates and two different lineages could be differentiated, lineages PG and TR. Phylogenetic analysis of the cyt b gene further showed that L. siamensis lineage TR is closely related to L. enrietti, a parasite of guinea pigs.ConclusionThe finding of this study sheds further light on the relationships of L. siamensis, both in intra- and inter-species aspects. This information would be useful for further in-depth studies on the biological properties of this important parasite.

Kaempferol, a plant-derived flavonoid, has been reported to have activity against Japanese encephalitis virus (JEV) in BHK-21 cells. To determine the broader utility of this compound, we initially evaluated the activity of kaempferol against JEV and dengue virus (DENV) in HEK293T/17 cells. Results showed no significant antiviral activity against either virus. We subsequently investigated the activity of kaempferol against both JEV and DENV in BHK-21 cells. Results showed a significant inhibition of JEV infection but, surprisingly, a significant enhancement of DENV infection. The effect of kaempferol on both host protein expression and transcription was investigated and both transcriptional and translational inhibitory effects were observed, although a more marked effect was observed on host cell protein expression. Markedly, while GRP78 was increased in DENV infected cells treated with kaempferol, it was not increased in JEV infected cells treated with kaempferol. These results show that cellular alteration induced by one compound can have opposite effects on viruses from the same family, suggesting the presence of distinct replication strategies for these two viruses.