Orientia tsutsugamushi Infection in Wild Small Mammals in Western Yunnan Province, China.

Small mammals can transmit and serve as a reservoir for Orientia tsutsugamushi (Ot) in nature by carrying infected mites. In Yunnan, one of China's main foci of scrub typhus, etiological evidence and genetic diversity for Ot is limited. A total of 2538 small mammals were captured seasonally from 2015 to 2016 in the three counties of Yunnan, and the spleen or liver tissue was examined for Ot based on 56 kDa nPCR. The overall prevalence of Ot was 1.77%, ranging from 0.26 to 9.09% across different species. The Gilliam strain was found in 35.6% (16/45) of the wild small mammals, followed by the Karp 11.1% (5/45) and TA763 (1/45) strains, the last of which was discovered in western Yunnan for the first time. In Lianghe, Ot infection rates in wild small mammals were higher than in the other two counties. The infection rates of Eothenomys miletus with Ot were highest in the three dominant species. Ot infection rates in wild small mammals were higher in Lianghe (1200-1400 m) and Yulong (2800-3000 m). These findings could provide research clues for further confirmation of scrub typhus foci in western Yunnan or other similar natural environments.

Molecular detection of Bartonella species in wild small mammals in western Yunnan Province, China.

Background: Small mammals serve as the main reservoir for Bartonella and as a proxy indicator of the potential risk of Bartonella transmission from nature to humans. They offer a valuable early warning for human infection. Nevertheless, geographical variations in the impact of the host on the occurrence of Bartonella infection are underestimated. This study was designed to investigate the infection characteristics of Bartonella and explore its species diversity in wild small mammals in western Yunnan Province, China. Methods: Wild small mammals were captured from Yulong, Jianchuan, and Lianghe counties in western Yunnan Province between 2015 and 2016. Real-time quantitative PCR (qPCR) was used to detect Bartonella infection, and the Bartonella species were identified by phylogenetic analysis. The factors associated with Bartonella infection in small mammals were analyzed by the Chi-square Test. Results: The prevalence of Bartonella in small mammals was 47.85% (768/1605). Lianghe County had the highest Bartonella infection rate, with 56.27% of the samples tested positive, followed by a rate of 50.91% was tested in Yulong County, and 39.97% in Jianchuan County (p < 0.001). Bartonella was detected positive in a total 25 small mammal species, with infection rates ranging from 2.17% to 100%. Niviventer fulvescens had the highest Bartonella infection rate. In comparison with the dominant small mammal species, Eothenomys mileyus had the lowest Bartonella infection rate than that in Apodemus chevrieri, Rattus tanezumi, and Apodemus draco (p < 0.001). Male small mammals had a higher infection rate than females (p < 0.05). The prevalence of Bartonella in small mammals during the summer season was higher compared to the other three seasons (p < 0.001). Woodland landscape had the highest Bartonella infection rate (p < 0.001). Bartonella rochalimae, B. japonica, B. tribocorum, B. washoensis, B. sylvatica, and B. rattimassiliensis were obtained from infected small mammals. Conclusion: This study showed a high prevalence of Bartonella was detected with various Bartonella species in small mammals in Yulong, Jianchuan, and Lianghe counties of western Yunnan Province. These findings hold significant scientific clues, providing valuable reference points for further research of Bartonella natural foci in Yunnan or other analogues environments.

QSAR study of phenolic compounds and their anti-DPPH radical activity by discriminant analysis.

Phenolic compounds (PCs) could be applied to reduce reactive oxygen species (ROS) levels, and are used to prevent and treat diseases related to oxidative stress. QSAR study was applied to elucidate the relationship between the molecular descriptors and physicochemical properties of polyphenol analogues and their DPPH radical scavenging capability, to guide the design and discovery of highly-potent antioxidant substances more efficiently. PubMed database was used to collect 99 PCs with antioxidant activity, whereas, 105 negative PCs were found in ChEMBL database; their molecular descriptors were generated with Python's Rdkit package. While the molecular descriptors significantly related to the antioxidant activity of PCs were filtered by t-test. The prediction QSAR model was then established by discriminant analysis, and the obtained model was verified by the back-substitution and Leave-One-Out cross-validation methods along with heat map. It was revealed that the anti-DPPH radical activity of PCs was correlated with the drug-likeness and molecular fingerprints, physicochemical, topological, constitutional and electronic property. The established QSAR model could explicitly predict the antioxidant activity of polyphenols, thus were applicable to evaluate the potential of candidates as antioxidants.

Seroepidemiology and genetic characterization of hepatitis E virus in western Yunnan Province.

OBJECTIVE: To investigate the seroepidemiology and genetic characterization of hepatitis E virus (HEV) in western Yunnan Province. METHODS: Questionnaire survey was conducted among 1638 residents in western Yunnan Province using stratified sampling method. Enzyme-linked immunosorbent assay was used to detect serum anti-HEV IgG and IgM. HEV RNA was extracted from patients with serum anti-HEV IgM positive. The open reading flame 2 (ORF2) of HEV that was amplified by nested RT-PCR was sequenced and compared with standard HEV genotypes 1-4. RESULTS: Serum anti-HEV positive was found in 13.92% (228/1638) residents. The HEV infection rate in males was significantly higher than that in females with a ratio of 1.47 (P<0.01). 20-30 and 30-40 years old young men showed the highest incidence, 20.57% and 20.78%, respectively. While 10-20 and 20-30 years old young women exhibited the highest infection rate, 11.85% and 15.60%, respectively. According to occupation, the highest HEV infection rate was observed in farmers (20.35%) and migrants (16.50%). We isolated 10 individual HEV isolates from 31 patients with serum anti-HEV IgM positive. Homology analysis and phylogenetic analysis indicated that these 10 HEV isolates belonged to HEV genotype 4 with the homology of 78.65%-94.71%. CONCLUSIONS: The HEV infection rate is high in western Yunnan Province. HEV genotype 4 is the leading cause of HEV infection and young farmers and migrants are the main infected population.