The discovery of novel variants reveals the genetic diversity and potential origin of Seoul orthohantavirus.

Seoul orthohantavirus (SEOV) has been identified as one of the main causative agents of hemorrhagic fever with renal syndrome (HFRS) in China. The virus was found circulating in rodent populations in almost all provinces of the country, reflecting the wide distribution of HFRS. Here, using the direct immunofluorescence assay (DFA) and real-time quantitative reverse transcription PCR (qRT-PCR) approach, we performed screening in 1784 small mammals belonging to 14 species of three orders captured in the main areas of HFRS endemicity in Yunnan province (southwestern China) and identified 37 SEOV-positive rats (36 Rattus norvegicus and 1 Rattus tanezumi). A 3-year surveillance of HFRS epidemics and dynamics of rodent reservoir density and virus prevalence implied a potential correlation between them. The subsequent meta-transcriptomic sequencing and phylogenetic analyses revealed three SEOV variants, among which two are completely novel. The ancestral character state reconstruction (ACSR) analysis based on both novel variants and documented strains from 5 continents demonstrated that SEOV appeared to originate near the southwestern area (Yunnan-Kweichow Plateau) of China, then could spread to other regions and countries by their rodent carriers, resulting in a global distribution today. In summary, these data furthered the understanding regards genetic diversity and the potential origin for SEOV. However, the expanding endemic foci in the province suggest that the virus is spreading over a wider region and is much more diverse than previous depicted, which means that increased sampling is necessary.

Status and analysis of undetected plague cases in Yunnan Province, China.

Background: The virulence of Yersinia pestis strains in the Rattus flavipectus plague focus is relatively low. The purpose of this study was to investigate the undetected, sporadic plague cases in plague foci and provide the basis for plague prevention and control. Methods: A 3-year-old plague-confirmed case was investigated in the R. flavipectus plague focus of Yunnan Province in 2020 due to the intensive screening for fever symptoms during the coronavirus disease 2019 (COVID-19) pandemic. Epidemiological investigation, laboratory testing, and clinical treatment were conducted for the case. The expanded survey was carried out around the case within a 7-km radius, including the resident population, domesticated dogs, and rats. PCR and indirect hemagglutination tests were performed on the collected samples. Results: The isolation rates of Y. pestis were 100.0% (7 out of 7) in dead rats and 4.00% (3 out of 75) in live rats in the survey area of the foci. A total of 5.00% (6 out of 120) of the domesticated dogs were F1 antibody positive. Nine local people were determined for plague infection recently (0.92%, 9 out of 978). The locations of human cases coincided with the Y. pestis epidemic area among the animals. Conclusion: This study discovered the existence of plague cases that had not been detected by routine surveillance in the R. flavipectus plague focus, and the actual epidemic of human infection may be underestimated.

Zoonotic pathogens identified in rodents and shrews from four provinces, China, 2015-2022.

Rodents and shrews are major reservoirs of various pathogens that are related to zoonotic infectious diseases. The purpose of this study was to investigate co-infections of zoonotic pathogens in rodents and shrews trapped in four provinces of China. We sampled different rodent and shrew communities within and around human settlements in four provinces of China and characterised several important zoonotic viral, bacterial, and parasitic pathogens by PCR methods and phylogenetic analysis. A total of 864 rodents and shrews belonging to 24 and 13 species from RODENTIA and EULIPOTYPHLA orders were captured, respectively. For viral pathogens, two species of hantavirus (Hantaan orthohantavirus and Caobang orthohantavirus) were identified in 3.47% of rodents and shrews. The overall prevalence of Bartonella spp., Anaplasmataceae, Babesia spp., Leptospira spp., Spotted fever group Rickettsiae, Borrelia spp., and Coxiella burnetii were 31.25%, 8.91%, 4.17%, 3.94%, 3.59%, 3.47%, and 0.58%, respectively. Furthermore, the highest co-infection status of three pathogens was observed among Bartonella spp., Leptospira spp., and Anaplasmataceae with a co-infection rate of 0.46%. Our results suggested that species distribution and co-infections of zoonotic pathogens were prevalent in rodents and shrews, highlighting the necessity of active surveillance for zoonotic pathogens in wild mammals in wider regions.

Individual bat virome analysis reveals co-infection and spillover among bats and virus zoonotic potential.

Bats are reservoir hosts for many zoonotic viruses. Despite this, relatively little is known about the diversity and abundance of viruses within individual bats, and hence the frequency of virus co-infection and spillover among them. We characterize the mammal-associated viruses in 149 individual bats sampled from Yunnan province, China, using an unbiased meta-transcriptomics approach. This reveals a high frequency of virus co-infection (simultaneous infection of bat individuals by multiple viral species) and spillover among the animals studied, which may in turn facilitate virus recombination and reassortment. Of note, we identify five viral species that are likely to be pathogenic to humans or livestock, based on phylogenetic relatedness to known pathogens or in vitro receptor binding assays. This includes a novel recombinant SARS-like coronavirus that is closely related to both SARS-CoV and SARS-CoV-2. In vitro assays indicate that this recombinant virus can utilize the human ACE2 receptor such that it is likely to be of increased emergence risk. Our study highlights the common occurrence of co-infection and spillover of bat viruses and their implications for virus emergence.

Associations between ecological diversity and rodent plague circulation in Yunnan Province, China, 1983-2020: A data-informed modelling study.

BACKGROUND: Following its resurgence in 1982, rodent plague has been linked to a wide range of circulation risks in Yunnan Province. The most serious public health concern associated with effective plague control is determining how various ecological variables influence the differential risk of transmission. METHODS: We investigated the population dynamics of the hosts and vectors using large-scale epidemiological surveillance data. In a seasonal eco-epidemiological model, we evaluated the impact of ecological conditions on the vectored flea index (VFI) to determine the rate of plague transmission. RESULTS: The findings revealed a changing species composition in natural foci over time. Additionally, shifting distributional ranges of species by elevation may be vital in modulating the VFI. The model estimates indicate that the dynamic VFI contributes to spatiotemporal variance in transmission. CONCLUSIONS: The VFI could be a critical ecological indicator, allowing for real-time tracking and prompt intervention in the circulation of rodent plague. Understanding eco-epidemiological diversity can provide essential insights into effective responses to future plague resurgence.

Individual bat viromes reveal the co-infection, spillover and emergence risk of potential zoonotic viruses.

Bats are reservoir hosts for many zoonotic viruses. Despite this, relatively little is known about the diversity and abundance of viruses within bats at the level of individual animals, and hence the frequency of virus co-infection and inter-species transmission. Using an unbiased meta-transcriptomics approach we characterised the mammalian associated viruses present in 149 individual bats sampled from Yunnan province, China. This revealed a high frequency of virus co-infection and species spillover among the animals studied, with 12 viruses shared among different bat species, which in turn facilitates virus recombination and reassortment. Of note, we identified five viral species that are likely to be pathogenic to humans or livestock, including a novel recombinant SARS-like coronavirus that is closely related to both SARS-CoV-2 and SARS-CoV, with only five amino acid differences between its receptor-binding domain sequence and that of the earliest sequences of SARS-CoV-2. Functional analysis predicts that this recombinant coronavirus can utilize the human ACE2 receptor such that it is likely to be of high zoonotic risk. Our study highlights the common occurrence of inter-species transmission and co-infection of bat viruses, as well as their implications for virus emergence.

Epidemiological Characteristics of Human and Animal Plague in Yunnan Province, China, 1950 to 2020.

This study analyzed the epidemiological characteristics of 3,464 human plague cases and the distribution pattern of 4,968 Yersinia pestis isolates from humans, hosts, and vector insects from 1950 to 2020 among two natural plague foci in Yunnan Province, China. These foci include the Rattus flavipectus plague focus of the Yunnan, Guangdong, and Fujian provinces and the Apodemus chevrieri-Eothenomys miletus plague focus of the highlands of northwestern Yunnan Province. The case fatality rate for plague in humans was 18.39% (637/3,464), and the total isolation rate of Y. pestis was 0.17% (4,968/2,975,288). Despite that the frequency of human cases declined rapidly, the animal plague fluctuated greatly, alternating between activity and inactivity in these foci. The tendency among human cases can be divided into 4 stages, 1950 to 1955, 1956 to 1989, 1990 to 2005, and 2006 to 2020. Bubonic plague accounted for the majority of cases in Yunnan, where pneumonic and septicemic plague rarely occurred. The natural plague foci have been in a relatively active state due to the stability of local ecology. Dense human population and frequent contact with host animals contribute to the high risk of human infection. This study systematically analyzed the epidemic pattern of human plague and the distribution characteristics of Y. pestis in the natural plague foci in Yunnan, providing a scientific basis for further development and adjustment of plague prevention and control strategies. IMPORTANCE Yunnan is the origin of the third plague pandemic. The analysis of human and animal plague characteristics of plague foci in Yunnan enlightens the prevention and control of the next plague pandemics. The plague characteristics of Yunnan show that human plague occurred when animal plague reached a certain scale, and strengthened surveillance of animal plague and reducing the density of host animals and transmission vectors contribute to the prevention and control of human plague outbreaks. The phenomenon of alternation between the resting period and active period of plague foci in Yunnan further proves the endogenous preservation mechanism of plague.

An HFman Probe-Based Multiplex Reverse Transcription Loop-Mediated Isothermal Amplification Assay for Simultaneous Detection of Hantaan and Seoul Viruses.

Hantaviruses are zoonotic pathogens that are widely distributed worldwide. Hantaan virus (HTNV) and Seoul virus (SEOV) are two most common hantaviruses that infect humans and cause hemorrhagic fever with renal syndrome (HFRS). Rapid and sensitive detection of HTNV and SEOV are crucial for surveillance, clinical treatment and management of HFRS. This study aimed to develop a rapid HFman probe-based mulstiplex reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay to simultaneously detect HTNV and SEOV. A novel multiplex RT-LAMP assay was developed, and 46 serum samples obtained from clinically suspected patients were used for evaluation. The novel RT-LAMP assay can detect as low as 3 copies/reaction of hantaviruses with a detection limit of 41 and 73 copies per reaction for HTNV and SEOV, respectively. A clinical evaluation showed that the consistencies of the multiplex RT-LAMP with RT-qPCR assay were 100% and 97.8% for HTNV and SEOV, respectively. In view of the high prevalence of HTNV and SEOV in rural areas with high rodent density, a colorimetric visual determination method was also developed for point-of-care testing (POCT) for the diagnosis of the two viruses. The novel multiplex RT-LAMP assay is a sensitive, specific, and efficient method for simultaneously detecting HTNV and SEOV.

Investigation of Negative Bias Temperature Instability Effect in Nano PDSOI PMOSFET.

The Negative Bias Temperature Instability (NBTI) effect of partially depleted silicon-on-insulator (PDSOI) PMOSFET based on 130 nm is investigated. First, the effect of NBTI on the IV characteristics and parameter degradation of T-Gate PDSOI PMOSFET was investigated by accelerated stress tests. The results show that NBTI leads to a threshold voltage negative shift, saturate drain current reduction and transconductance degradation of the PMOSFET. Next, the relationship between the threshold voltage shift and stress time, gate bias and temperature, and the channel length is investigated, and the NBTI lifetime prediction model is established. The results show that the NBTI lifetime of a 130 nm T-Gate PDSOI PMOSFET is approximately 18.7 years under the stress of VG = -1.2 V and T = 125 °C. Finally, the effect of the floating-body effect on NBTI of PDSOI PMOSFET is investigated. It is found that the NBTI degradation of T-Gate SOI devices is greater than that of the floating-body SOI devices, which indicates that the floating-body effect suppresses the NBTI degradation of SOI devices.

Investigation on Ehrlichia Infection in Small Mammals and Ticks from Tengchong, Yunnan Province, Southern China.

BACKGROUND: Rare investigation on tick-borne pathogens was carried out in Yunnan, China. In this study, we did a survey on Ehrlichia infection in small mammals and ticks. A total of 40 small mammals and 49 ticks were collected from Tengchong, Yunnan province. PCR targeting 16S ribosomal RNA (rRNA), citrate synthase, GroEL heat-shock protein operon, and major outer membrane protein genes was performed and positive amplicons were sequenced. RESULTS: The 40 small mammals were identified as 10 species, 2 (5.0%) of which were infected with Ehrlichia, 4 (10.0%) were infected with Anaplasma phagocytophilum and another 2 (5.0%) were infected with Candidatus Neoehrlichia mikurensis. Six (12.2%) ticks were positive for Ehrlichia and another two (4.1%) were infected with A. phagocytophilum. Neither small mammals nor ticks had coinfection. The detected Ehrlichia was named as Ehrlichia sp. YN04, which was in the same clade of Ehrlichia sp. 360 by phylogenetic analysis. The sequences of the pathogen recovered from small mammals and ticks were identical with each other. CONCLUSION: The study reports one Ehrlichia species first detected from small mammals and ticks in mainland China. As Yunnan is a famous "Global Biodiversity Hotspot" in the world, we may expect much more tick-borne infectious pathogens existing and declare more public health attention in this region.

Wide Distribution and Genetic Diversity of Babesia microti in Small Mammals from Yunnan Province, Southwestern China.

BACKGROUND: Babesia, usually found in wild and domestic mammals worldwide, have recently been responsible for emerging malaria-like zoonosis in infected patients. Human B. microti infection has been identified in China, primarily in the Southwest along the Myanmar border but little direct surveillance of B. microti infection in rodents has been carried out here (Yunnan province). In this region, a diverse topographic range combined with tropical moisture sustains a high biodiversity of small mammals, which might play important role on Babesia transmission. METHODS: Small mammals were captured in 141 sample locations from 18 counties located Yunnan Province, and screened for B. microti-like parasites infection by a nested PCR to target 18S rRNA gene of Babesia, plus directly sequencing for positive samples. Univariate and multivariate forward stepwise logistic regression analysis was used to access the association between infections and some related risk factors. RESULTS: Infection with Babesia microti was confirmed in 2.4% (53/ 2204) of small mammals. Significant differences in prevalence rates of B. microti were observed based on variations in forest, agricultural, and residential landscapes. Furthermore, adult small mammals had higher prevalence rates than younger, pubertal mammals. The near full-length 18S rRNA gene revealed that there were two types of B. microti, Kobe and Otsu, which demonstrate the genetic diversity and regional distribution. CONCLUSIONS: There exists a wide distribution and genetic diversity of endemic B. microti in Southwestern China, warranting further investigations and monitoring of clinical disease in individuals presenting with Babesia like symptoms in these areas.