Species identification and phylogenetic analysis of Leishmania isolated from patients, vectors and hares in the Xinjiang Autonomous Region, The People's Republic of China.

BACKGROUND: Visceral leishmaniasis (VL) has been declared as one of the six major tropical diseases by the World Health Organization. This disease has been successfully controlled in China, except for some areas in the western region, such as the Xinjiang Autonomous Region, where both anthroponotic VL (AVL) and desert type zoonotic VL (DT-ZVL) remain endemic with sporadic epidemics. METHODOLOGY/PRINCIPAL FINDINGS: Here, an eleven-year survey (2004-2014) of Leishmania species, encompassing both VL types isolated from patients, sand-fly vectors and Tarim hares (Lepus yarkandensis) from the Xinjiang Autonomous Region was conducted, with a special emphasis on the hares as a potential reservoir animal for DT-ZVL. Key diagnostic genes, ITS1, hsp70 and nagt (encoding N-acetylglucosamine-1-phosphate transferase) were used for phylogenetic analyses, placing all Xinjiang isolates into one clade of the L. donovani complex. Unexpectedly, AVL isolates were found to be closely related to L. infantum, while DT-ZVL isolates were closer to L. donovani. Unrooted parsimony networks of haplotypes for these isolates also revealed their relationship. CONCLUSIONS/SIGNIFICANCE: The above analyses of the DT-ZVL isolates suggested their geographic isolation and independent evolution. The sequence identity of isolates from patients, vectors and the Tarim hares in a single DT-ZVL site provides strong evidence in support of this species as an animal reservoir.

Innate Resistance to Leishmania amazonensis Infection in Rat Is Dependent on NOS2.

Leishmania infection causes diverse clinical manifestations in humans. The disease outcome is complicated by the combination of many host and parasite factors. Inbred mouse strains vary in resistance to Leishmania major but are highly susceptible to Leishmania amazonensis infection. However, rats are highly resistant to L. amazonensis infection due to unknown mechanisms. We use the inducible nitric oxide synthase (Nos2) gene knockout rat model (Nos2 -/- rat) to investigate the role of NOS2 against leishmania infection in rats. Our results demonstrated that diversion toward the NOS2 pathway is the key factor explaining the resistance of rats against L. amazonensis infection. Rats deficient in NOS2 are susceptible to L. amazonensis infection even though their immune response to infection is still strong. Moreover, adoptive transfer of NOS2 competent macrophages into Nos2 -/- rats significantly reduced disease development and parasite load. Thus, we conclude that the distinct L-arginine metabolism, observed in rat macrophages, is the basis of the strong innate resistance to Leishmania. These data highlight that macrophages from different hosts possess distinctive properties and produce different outcomes in innate immunity to Leishmania infections.

Nitric oxide blocks the development of the human parasite Schistosoma japonicum.

Human schistosomiasis, caused by Schistosoma species, is a major public health problem affecting more than 700 million people in 78 countries, with over 40 mammalian host reservoir species complicating the transmission ecosystem. The primary cause of morbidity is considered to be granulomas induced by fertilized eggs of schistosomes in the liver and intestines. Some host species, like rats (Rattus norvegicus), are naturally intolerant to Schistosoma japonicum infection, and do not produce granulomas or pose a threat to transmission, while others, like mice and hamsters, are highly susceptible. The reasons behind these differences are still a mystery. Using inducible nitric oxide synthase knockout (iNOS-/-) Sprague-Dawley rats, we found that inherent high expression levels of iNOS in wild-type (WT) rats play an important role in blocking growth, reproductive organ formation, and egg development in S. japonicum, resulting in production of nonfertilized eggs. Granuloma formation, induced by fertilized eggs in the liver, was considerably exacerbated in the iNOS-/- rats compared with the WT rats. This inhibition by nitric oxide acts by affecting mitochondrial respiration and energy production in the parasite. Our work not only elucidates the innate mechanism that blocks the development and production of fertilized eggs in S. japonicum but also offers insights into a better understanding of host-parasite interactions and drug development strategies against schistosomiasis.

[Pathogen Identification in an Imported Case of Cutaneous Leishmaniasis].

In this study, immune and molecular biological methods were used to identify the pathogen in a blood sample from a patient with dermatosis. Venous blood was collected and tested with Leish rK39 dipsticks. The lesion sample was collected and fixed in 75% ethanol, and DNA was extracted. The internal transcribed spacer 1 of rDNA and N-acetylglucosamine-1-phosphate transferase of Leishmania were amplified with PCR using primers LITSR-L5.8S and NAGTL1s-NAGTL4, respectively. The amplified products were sequenced and analyzed by BLAST. Weakly positive results were obtained for the gold-labeled Leish rK39 dipstick serological test. PCR resulted in products of 404 bp and 1 405 bp with primers LITSR-L5.8S and NAGTL1-NAGTL4, respectively. Both were 99.7% homologous to the corresponding sequence of Leishmania major. The accession number of the two sequences were KU975160 and KX150476. The case of dermatosis is diagnosed as imported cutaneous leishmaniasis and the pathogen is L. major.

Visceral Leishmaniasis in China: an Endemic Disease under Control.

Visceral leishmaniasis (VL) caused by Leishmania spp. is an important vector-borne and largely zoonotic disease. In China, three epidemiological types of VL have been described: anthroponotic VL (AVL), mountain-type zoonotic VL (MT-ZVL), and desert-type ZVL (DT-ZVL). These are transmitted by four different sand fly species: Phlebotomus chinensis, P. longiductus, P. wui, and P. alexandri. In 1951, a detailed survey of VL showed that it was rampant in the vast rural areas west, northwest, and north of the Yangtze River. Control programs were designed and implemented stringently by the government at all administrative levels, resulting in elimination of the disease from most areas of endemicity, except the western and northwestern regions. The control programs consisted of (i) diagnosis and chemotherapy of patients, (ii) identification, isolation, and disposal of infected dogs, and (iii) residual insecticide indoor spraying for vector control. The success of the control programs is attributable to massive and effective mobilization of the general public and health workers to the cause. Nationally, the annual incidence is now very low, i.e., only 0.03/100,000 according to the available 2011 official record. The overwhelming majority of cases are reported from sites of endemicity in the western and northwestern regions. Here, we describe in some depth and breadth the current status of epidemiology, diagnosis, treatment, and prevention of the disease, with particular reference to the control programs. Pertinent information has been assembled from scattered literature of the past decades in different languages that are not readily accessible to the scientific community. The information provided constitutes an integral part of our knowledge on leishmaniasis in the global context and will be of special value to those interested in control programs.

In vitro and in vivo efficacy of novel flavonoid dimers against cutaneous leishmaniasis.

Treatment of leishmaniasis by chemotherapy remains a challenge because of limited efficacy, toxic side effects, and drug resistance. We previously reported that synthetic flavonoid dimers have potent antipromastigote and antiamastigote activity against Leishmania donovani, the causative agent of visceral leishmaniasis. Here, we further investigate their leishmanicidal activities against cutaneous Leishmania species. One of the flavonoid dimers (compound 39) has marked antipromastigote (50% inhibitory concentrations [IC50s], 0.19 to 0.69 µM) and antiamastigote (IC50s, 0.17 to 2.2 µM) activities toward different species of Leishmania that cause cutaneous leishmaniasis, including Leishmania amazonensis, Leishmania braziliensis, Leishmania tropica, and Leishmania major. Compound 39 is not toxic to peritoneal elicited macrophages, with IC50 values higher than 88 µM. In the mouse model of cutaneous leishmaniasis induced by subcutaneous inoculation of L. amazonensis in mouse footpads, intralesional administration of 2.5 mg/kg of body weight of compound 39.HCl can reduce footpad thickness by 36%, compared with that of controls values. The amastigote load in the lesions was reduced 20-fold. The present study suggests that flavonoid dimer 39 represents a new class of safe and effective leishmanicidal agent against visceral and cutaneous leishmaniasis.