Highly potent multivalent VHH antibodies against Chikungunya isolated from an alpaca naïve phage display library.

BACKGROUND: Chikungunya virus (CHIKV) is a re-emerged mosquito-borne alphavirus that can cause musculoskeletal diseases, imposing a substantial threat to public health globally. High-affinity antibodies are need for diagnosis and treatment of CHIKV infections. As a potential diagnostic and therapeutic agent, the multivalent VHH antibodies is a promising tookit in nanomedicine. Here, we developed potent multivalent VHH antibodies from an alpaca naïve phage display library targeting the E2 glycoprotein of the CHIKV virus. RESULTS: In the present study, we generated 20 VHH antibodies using a naïve phage display library for binders to the CHIKV E2 glycoprotein. Of these, multivalent VHH antibodies Nb-2E8 and Nb-3C5 had specific high-affinity binding to E2 protein within the nanomolar range. The equilibrium dissociation constant (KD) was between 2.59-20.7 nM, which was 100-fold stronger than the monovalent antibodies' affinity. Moreover, epitope mapping showed that Nb-2E8 and Nb-3C5 recognized different linear epitopes located on the E2 glycoprotein domain C and A, respectively. A facile protocol of sandwich ELISA was established using BiNb-2E8 as a capture antibody and HRP-conjugated BiNb-3C5 as a detection antibody. A good linear correlation was achieved between the OD450 value and the E2 protein concentration in the 5-1000 ng/mL range (r = 0.9864, P < 0.0001), indicating its potential for quantitative detection of the E2 protein. CONCLUSIONS: Compared to monovalent antibodies, multivalent VHH antibodies Nb-2E8 and Nb-3C5 showed high affinity and are potential candidates for diagnostic applications to better detect CHIKV virions in sera.

Ubiquitin-Modified Proteome of SARS-CoV-2-Infected Host Cells Reveals Insights into Virus-Host Interaction and Pathogenesis.

The outbreak of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to global public health. The mechanism of pathogenesis and the host immune response to SARS-CoV-2 infection are largely unknown. In the present study, we applied a quantitative proteomic technology to identify and quantify the ubiquitination changes that occur in both the virus and the Vero E6 cells during SARS-CoV-2 infection. By applying label-free, quantitative liquid chromatography with tandem mass spectrometry proteomics, 8943 lysine ubiquitination sites on 3086 proteins were identified, of which 138 sites on 104 proteins were quantified as significantly upregulated, while 828 sites on 447 proteins were downregulated at 72 h post-infection. Bioinformatics analysis suggested that SARS-CoV-2 infection might modulate host immune responses through the ubiquitination of important proteins, including USP5, IQGAP1, TRIM28, and Hsp90. Ubiquitination modification was also observed on 11 SAR-CoV-2 proteins, including proteins involved in virus replication and inhibition of the host innate immune response. Our study provides new insights into the interaction between SARS-CoV-2 and the host as well as potential targets for the prevention and treatment of COVID-19.

The Pearl River Declaration: a timely call for enhancing health security through fostering a regional one health collaboration in the Asia-Pacific.

The Second International Symposium on One Health Research (ISOHR) was held in Guangzhou city, China on 23-24 November 2019. A transdisciplinary collaborative approach, One Health (OH), was the central theme of the symposium which brought together more than 260 experts, scholars and emerging researchers from human health, veterinary health, food safety, environmental health and related disciplines and sectors. More than 50 organizations including World Health Organization, Centers for Disease Control (USA), and Queensland Government (Australia) participated in the symposium. Scholars, experts and emerging researchers, policy-makers and practitioners in their respective fields delivered over 50 presentations at the symposium, highlighting the collective vulnerability to some of the emerging health challenges the region was combating. These included emerging infectious diseases, antimicrobial resistance, climate change, food safety and the growing burden of non-communicable diseases. The Pearl River Declaration, emanated from the symposium, called for establishing a One Health Cooperation Network in the Southeast Asia-Pacific region with a vision to strengthen regional health security through sharing each other's knowledge and experience, and making investments in workforce development, scientific innovations such as vaccine research and development, sharing epidemic intelligence, risk identification, risk communication and appropriate response measures against emerging health threats.

A Comparative Study of Associated Microbiota Between Pig Farm and Pig Slaughterhouse in Guangdong, China.

The goal of this study was to compare the microbiota in different pig-present settings in China. Bioaerosol samples from pig farms and slaughterhouses and nasal samples from pig farmers and slaughterhouse workers were collected in Guangdong, southern China. The bacterial genomic DNA was isolated and subjected to 16S sequencing. The data were analyzed using QIIME2 with the DADA2 pipeline. A total of 14,923,551 clean reads and 2785 operational taxonomic units (OTUs) were obtained, which were mostly grouped into 4 phyla (Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria) and 220 families. The microbiota richness of nasal samples in pig-present workers was higher than that of bioaerosols collected in the vicinity of the pig enclosures. There were 31.7% (620/1954) shared OTUs between pig farm bioaerosols and pig farmers which was higher than that between pig slaughterhouses and slaughterhouse workers (23.4%, 364/1553) (p < 0.001). Acinetobacter and Pseudomonas were the most abundant in pig-present bioaerosols, and Staphylococcus, Pseudomonas, and Corynebacterium were dominant bacterial genus in pig farmers. The bacterial patterns are also specific to the location of sample collected. The results suggest that bioaerosol microbiota interact with human nasal microbes in the vicinity of the pig farm enclosures, providing the basis for further analysis of microbial transmission across hosts in pig-present settings.

A Divalent Chikungunya and Zika Nanovaccine with Thermostable Self-Assembly Multivalent Scaffold LS-SUMO.

The convergence strategies of antigenic subunits and synthetic nanoparticle scaffold platform improve the vaccine production efficiency and enhance vaccine-induced immunogenicity. Selecting the appropriate nanoparticle scaffold is crucial to controlling target antigens immunologically. Lumazine synthase (LS) is an attractive candidate for a vaccine display system due to its thermostability, modification tolerance, and morphological plasticity. Here, the first development of a multivalent thermostable scaffold, LS-SUMO (SUMO, small ubiquitin-likemodifier), and a divalent nanovaccine covalently conjugated with Chikungunya virus E2 and Zika virus EDIII antigens, is reported. Compared with antigen monomers, LS-SUMO nanoparticle vaccines elicit a higher humoral response and neutralizing antibodies against both antigen targets in mouse sera. Mice immunized with LS-SUMO conjugates produce CD4+ T cell-mediated Th2-biased responses and promote humoral immunity. Importantly, LS-SUMO conjugates possess equivalent humoral immunogenicity after heat treatment. Taken together, LS-SUMO is a powerful biotargeting nanoplatform with high-yield production, thermal stability and opens a new avenue for multivalent presentation of various antigens.

IgM-specific linear epitopes on the E2 protein for serodiagnosis of Chikungunya.

Chikungunya virus (CHIKV) and Dengue virus (DENV) are vector-borne diseases transmitted by Aedes aegypti and Aedes albopictus that pose a significant threat to global public health. Cases of acute Chikungunya fever often present similar clinical symptoms to other vector-borne diseases, such as Dengue fever. In regions where multiple vector-borne diseases coexist, CHIKV is often overlooked or misdiagnosed as Dengue virus, West Nile virus, Zika virus or other viral infections, which delays its prevention and control. However, IgM antibodies directed against the E2 protein of CHIKV have not yet been generalized to clinical settings due to the low sensitivity and high cost in commercial kits. Indirect ELISA with peptides provides an effective supplementary tool for detecting CHIKV IgM antibodies. Our study aims at examining the potential of linear epitopes on the E2 glycoprotein that specifically bind to IgM antibodies as serodiagnostic tool for CHIKV. The sensitivity of the established peptide indirect ELISA method for detecting clinical samples is significantly better than that of commercial kits, realizing a beneficial supplement to the existing IgM antibody assay. It also established the groundwork for comprehending the biological mechanisms of the CHIKV E2 protein and the advancement of innovative epitope peptide vaccines.

A rapid and sensitive fluorescent chromatography with cloud system for MPXV point-of-care diagnosis.

Monkeypox (mpox) is spreading around the world, and its rapid diagnosis is of great significance. In the present study, a rapid and sensitive fluorescent chromatography assisted with cloud system was developed for point-of-care diagnosis of mpox. To screen high affinity antibodies, nanoparticle antigen AaLS-A29 was generated by conjugating A29 onto scaffold AaLS. Immunization with AaLS-A29 induced significantly higher antibody titers and monoclonal antibodies were generated with the immunized mice. A pair of monoclonal antibodies, MXV 14 and MXV 15, were selected for fluorescence chromatography development. The Time-Resolved Fluorescence Immunoassay (TRFIA) was used to develop the chromatography assay. After optimization of the label and concentration of antibodies, a sensitive TRFIA assay with detection limit of 20 pg/mL and good repeatability was developed. The detection of the surrogate Vaccinia virus (VACA) strain Tian Tan showed that the TRFIA assay was more sensitive than the SYBR green I based quantitative PCR. In real samples, the detection result of this assay were highly consistent with the judgement of Quantitative Real-Time PCR (Concordance Rate = 90.48%) as well as the clinical diagnosis (Kappa Value = 0.844, P < 0.001). By combining the portable detection and online cloud system, the detection results could be uploaded and shared, making this detection system an ideal system for point-of-care diagnosis of mpox both in field laboratory and outbreak investigation.

T Cell Activating Thermostable Self-Assembly Nanoscaffold Tailored for Cellular Immunity Antigen Delivery.

Antigen delivery based on non-virus-like particle self-associating protein nanoscffolds, such as Aquifex aeolicus lumazine synthase (AaLS), is limited due to the immunotoxicity and/or premature clearance of antigen-scaffold complex resulted from triggering unregulated innate immune responses. Here, using rational immunoinformatics prediction and computational modeling, we screen the T epitope peptides from thermophilic nanoproteins with the same spatial structure as hyperthermophilic icosahedral AaLS, and reassemble them into a novel thermostable self-assembling nanoscaffold RPT that can specifically activate T cell-mediated immunity. Tumor model antigen ovalbumin T epitopes and the severe acute respiratory syndrome coronavirus 2 receptor-binding domain are loaded onto the scaffold surface through the SpyCather/SpyTag system to construct nanovaccines. Compared to AaLS, RPT -constructed nanovaccines elicit more potent cytotoxic T cell and CD4+ T helper 1 (Th1)-biased immune responses, and generate less anti-scaffold antibody. Moreover, RPT significantly upregulate the expression of transcription factors and cytokines related to the differentiation of type-1 conventional dendritic cells, promoting the cross-presentation of antigens to CD8+ T cells and Th1 polarization of CD4+ T cells. RPT confers antigens with increased stability against heating, freeze-thawing, and lyophilization with almost no antigenicity loss. This novel nanoscaffold offers a simple, safe, and robust strategy for boosting T-cell immunity-dependent vaccine development.

A Multivalent and Thermostable Nanobody Neutralizing SARS-CoV-2 Omicron (B.1.1.529).

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants have risen to dominance, which contains far more mutations in the spike protein in comparison to previously reported variants, compromising the efficacy of most existing vaccines or therapeutic monoclonal antibodies. Nanobody screened from high-throughput naïve libraries is a potential candidate for developing preventive and therapeutic antibodies. Methods: Four nanobodies specific to the SARS-CoV-2 wild-type receptor-binding domain (RBD) were screened from a naïve phage display library. Their affinity and neutralizing activity were evaluated by surface plasmon resonance assays, surrogate virus neutralization tests, and pseudovirus neutralization assays. Preliminary identification of the binding epitopes of nanobodies by peptide-based ELISA and competition assay. Then four multivalent nanobodies were engineered by attaching the monovalent nanobodies to an antibody-binding nanoplatform constructed based on the lumazine synthase protein cage nanoparticles isolated from the Aquifex aeolicus (AaLS). Finally, the differences in potency between the monovalent and multivalent nanobodies were compared using the same methods. Results: Three of the four specific nanobodies could maintain substantial inhibitory activity against the Omicron (B.1.1.529), of them, B-B2 had the best neutralizing activity against the Omicron (B.1.1.529) pseudovirus (IC50 = 1.658 µg/mL). The antiviral ability of multivalent nanobody LS-B-B2 was improved in the Omicron (B.1.1.529) pseudovirus assays (IC50 = 0.653 µg/mL). The results of peptide-based ELISA indicated that LS-B-B2 might react with the linear epitopes in the SARS-CoV-2 RBD conserved regions, which would clarify the mechanisms for the maintenance of potent neutralization of Omicron (B.1.1.529) preliminary. Conclusion: Our study indicated that the AaLS could be used as an antibody-binding nanoplatform to present nanobodies on its surface and improve the potency of nanobodies. The multivalent nanobody LS-B-B2 may serve as a potential agent for the neutralization of SARS-CoV-2 variants.

A meta-transcriptomic study of mosquito virome and blood feeding patterns at the human-animal-environment interface in Guangdong Province, China.

Mosquitoes are a formidable reservoir of viruses and important vectors of zoonotic pathogens. Blood-fed mosquitoes have been utilized to determine host infection status, overcoming the difficulties associated with sampling from human and animal populations. Comprehensive surveillance of potential pathogens at the interface of humans, animals, and the environment is currently an accredited method to provide an early warning of emerging or re-emerging infectious diseases and to proactively respond to them. Herein we performed comprehensive sampling of mosquitoes from seven habitats (residential areas, hospital, airplane, harbor, zoo, domestic sheds, and forest park) across five cities in Guangdong Province, China. Our aim was to characterize the viral communities and blood feeding patterns at the human-animal-environment interface and analyze the potential risk of cross-species transmission using meta-transcriptomic sequencing. 1898 female adult mosquitoes were collected, including 1062 Aedes and 836 Culex mosquitoes, of which approximately 12% (n = 226) were satiated with blood. Consequently, 101 putative viruses were identified, which included DNA and RNA viruses, and positive-stranded RNA viruses (+ssRNA) were the most abundant. According to viral diversity analysis, the composition of the viral structure was highly dependent on host species, and Culex mosquitoes showed richer viral diversity than Aedes mosquitoes. Although the virome of mosquitoes from different sampling habitats showed an overlap of 39.6%, multiple viruses were specific to certain habitats, particularly at the human-animal interface. Blood meal analysis found four mammals and one bird bloodmeal source, including humans, dogs, cats, poultry, and rats. Further, the blood feeding patterns of mosquitoes were found to be habitat dependent, and mosquitoes at the human-animal interface and from forests had a wider choice of hosts, including humans, domesticated animals, and wildlife, which in turn considerably increases the risk of spillover of potential zoonotic pathogens. To summarize, we are the first to investigate the virome of mosquitoes from multiple interfaces based on the One Health concept. The characteristics of viral community and blood feeding patterns of mosquitoes at the human-animal-environment interface were determined. Our findings should support surveillance activities to identify known and potential pathogens that are pathogenic to vertebrates.

A non-toxic recombinant Clostridium septicum α toxin induces protective immunity in mice and rabbits.

Clostridium septicum alpha toxin (CSA) plays significant roles in ruminant's braxy. Genetically engineered CSA has been shown to function as a potential vaccine candidate in the prevention of the disease caused by Clostridium septicum. In the present study, we synthesized a non-toxic recombinant, rCSAm4/TMD by introducing four amino acid substitutions (C86L/N296A/H301A/W342A) and 11-amino-acid deletion (residues 212 to 222). Compared to recombinant CSA, rCSAm4/TMD showed no cytotoxicity to MDCK cells and was not fatal to mice. Moreover, rCSAm4/TMD could protect immunized mice against 5 × mouse LD100 (100% lethal dose) of crude CSA without obvious pathological change. Most importantly, rabbits immunized with rCSAm4/TMD produced high titers of neutralizing antibodies which protected the rabbits against crude CSA challenge. These data suggest that genetically detoxified rCSAm4/TMD is a potential subunit vaccine candidate against braxy.

A One Health strategy for emerging infectious diseases based on the COVID-19 outbreak.

Coronavirus disease 2019 (COVID-19) is as an emerging infectious disease (EID) that has caused the worst public health catastrophe of the 21st century thus far. In terms of impact, the COVID-19 pandemic is second only to the Spanish Flu pandemic of 1918 in modern world history. As of 7 September 2021, there have been 220 million confirmed cases of COVID-19 and more than 4.5 million deaths. EIDs pose serious public health and socio-economic risks, and 70% of EIDs originate from wildlife. Preventing development of EIDs such as COVID-19 is a pressing concern. Here, taking the COVID-19 pandemic as an example, we illustrate the disastrous effects of EIDs and assess their emergence and evolution from a One Health perspective. We propose a One Health strategy, centered on 'moving the gates forward', for EID prevention and control at the human-animal-environment interface. This strategy may be instructive and provide early warnings of EIDs in the future.

Inhibition of Chikungunya virus early replication by intracellular nanoantibodies targeting nsP2 Epitope Rich Region.

Chikungunya fever, caused by Chikungunya virus (CHIKV), is an Aedes mosquito-borne disease present worldwide, and millions of CHIKV infections have been reported. Treatment for CHIKV includes supportive care and anti-inflammatory medications, but there are currently no antiviral treatments or vaccines. Nonstructural protein 2 (nsP2) of CHIKV is the most important functional protein mediating virus replication and amplification, making it an ideal antiviral target for CHIKV. In this study, we determined the CHIKV nsP2 Epitope Rich Region, expressed recombinant nsP2 protein, and isolated 5 nsP2-specific nanobodies (Nb-A2, Nb-A9, Nb-D7, Nb-D12 and Nb-E12) from a phage display library comprising variable domains of Camellidae heavy chain-only antibodies (VHH). We subsequently established a stable Nbs-expressing HEK293T cell line to explore antiviral function. The results showed that Nb-A9 inhibited CHIKV replication at the early stage of CHIKV infection in HEK293T cells, and protected cells against CHIKV-induced cytopathic effect (CPE). This is possibly the first report of an Nbs-based strategy against CHIKV nsP2, Nb-A9 has great potential for developing a novel antiviral drug to treat CHIKV infection. The acquisition of antibodies has laid a foundation for further research on the function of CHIKV nsP2 and the development of therapeutic drugs.

Development of a neutralizing antibody targeting linear epitope of the envelope protein domain III of ZIKV.

Zika virus (ZIKV) infection represents an emerging infectious disease that poses an increasing threat to human health, especially after the ZIKV outbreak in Brazil in 2015. Unfortunately, there continues to be a lack of highly effective antiviral drugs or vaccines against ZIKV. In this study, we expressed the ZIKV envelope protein domain III (ZIKV EDIII) in E. coli strain BL21. The purified recombinant protein was used to immunize mice to produce monoclonal antibodies (mAbs). After 6 screening and 5 subcloning cycles, 10 monoclonal cell lines that stably produced antibodies, termed 2F5, 5B8, 6G6, 7E12, 8B6, 17E6, 19E7, 20F4, 26G6, and 37E6, were identified. The mAb 8B6 could neutralize ZIKV and recognize the ZIKV EDIII epitope (GRLITANPVITESTE). Another 9 mAbs did not exhibit neutralizing activity; however, they could specifically recognize the ZIKV EDIII and ZIKV lysate, suggesting their potential use in the diagnosis of ZIKV.

Development of Immunochromatographic Assay for the Rapid Detection of Mycoplasma capricolum subsp. capripneumoniae Antibodies.

Mycoplasma capricolum subsp. capripneumoniae (Mccp) is the cause of contagious caprine pleuropneumonia (CCPP), which is a highly significant respiratory disease in goats leading to significant economic losses in Africa and Asia. Currently available procedures for the diagnosis of CCPP have some limitations in sensitivity, specificity, operation time, requirement of sophisticated equipment or skilled personnel, and cost. In this study, we developed a rapid, sensitive, and specific colloidal gold-based immunochromatographic assay (GICA) strip for the efficient on-site detection of antibodies against Mccp in the serum within 10 min. For the preparation of this colloidal GICA strip, recombinant P20 protein, the membrane protein of Mccp, was expressed by Escherichia coli prokaryotic expression system after purification was used as the binding antigen in the test. The rabbit anti-goat immunoglobulin G labeled with the colloidal gold was used as the detection probe, whereas the goat anti-rabbit immunoglobulin G was coated on the nitrocellulose membrane as the control line. The concentration of the coating antibody was optimized, and the effectiveness of this colloidal GICA strip was evaluated. Our results proved that the detection limit of the test strip was up to 1:64 dilutions for the Mccp antibody-positive serum samples with no cross-reactivity with other pathogens commonly infecting small ruminants,including goat pox virus, peste des petits ruminants virus, foot-and-mouth disease virus type A, or other mycoplasmas. Moreover, the colloidal GICA strip was more sensitive and specific than the indirect hemagglutination assay for the detection of Mccp antibodies. The 106 clinical serum samples were detected by the colloidal GICA strip compared with the complement fixation test, demonstrating an 87.74% concordance with the complement fixation test. This novel colloidal GICA strip would be an effective tool for the cost-effective and rapid diagnosis of CCPP in the field.

Pre-Existing Cross-Reactive Antibody Responses Do Not Significantly Impact Inactivated COVID-19 Vaccine-Induced Neutralization.

Recent exposure to seasonal coronaviruses (sCoVs) may stimulate cross-reactive antibody responses against severe acute respiratory syndrome CoV 2 (SARS-CoV-2). However, previous studies have produced divergent results regarding protective or damaging immunity induced by prior sCoV exposure. It remains unknown whether pre-existing humoral immunity plays a role in vaccine-induced neutralization and antibody responses. In this study, we collected 36 paired sera samples from 36 healthy volunteers before and after immunization with inactivated whole-virion SARS-CoV-2 vaccines for COVID-19, and analyzed the distribution and intensity of pre-existing antibody responses at the epitope level pre-vaccination as well as the relationship between pre-existing sCoV immunity and vaccine-induced neutralization. We observed large amounts of pre-existing cross-reactive antibodies in the conserved regions among sCoVs, especially the S2 subunit. Excep t for a few peptides, the IgG and IgM fluorescence intensities against S, M and N peptides did not differ significantly between pre-vaccination and post-vaccination sera of vaccinees who developed a neutralization inhibition rate (%inhibition) <40 and %inhibition ≥40 after two doses of the COVID-19 vaccine. Participants with strong and weak pre-existing cross-reactive antibodies (strong pre-CRA; weak pre-CRA) had similar %inhibition pre-vaccination (10.9% ± 2.9% vs. 12.0% ± 2.2%, P=0.990) and post-vaccination (43.8% ± 25.1% vs. 44.6% ± 21.5%, P=0.997). Overall, the strong pre-CRA group did not show a significantly greater increase in antibody responses to the S protein linear peptides post-vaccination compared with the weak pre-CRA group. Therefore, we found no evidence for a significant impact of pre-existing antibody responses on inactivated vaccine-induced neutralization and antibody responses. Our research provides an important basis for inactivated SARS-CoV-2 vaccine use in the context of high sCoV seroprevalence.

Immunoreactive peptide maps of SARS-CoV-2.

Serodiagnosis of SARS-CoV-2 infection is impeded by immunological cross-reactivity among the human coronaviruses (HCoVs): SARS-CoV-2, SARS-CoV-1, MERS-CoV, OC43, 229E, HKU1, and NL63. Here we report the identification of humoral immune responses to SARS-CoV-2 peptides that may enable discrimination between exposure to SARS-CoV-2 and other HCoVs. We used a high-density peptide microarray and plasma samples collected at two time points from 50 subjects with SARS-CoV-2 infection confirmed by qPCR, samples collected in 2004-2005 from 11 subjects with IgG antibodies to SARS-CoV-1, 11 subjects with IgG antibodies to other seasonal human coronaviruses (HCoV), and 10 healthy human subjects. Through statistical modeling with linear regression and multidimensional scaling we identified specific peptides that were reassembled to identify 29 linear SARS-CoV-2 epitopes that were immunoreactive with plasma from individuals who had asymptomatic, mild or severe SARS-CoV-2 infections. Larger studies will be required to determine whether these peptides may be useful in serodiagnostics.

Distribution of the COVID-19 epidemic and correlation with population emigration from Wuhan, China.

BACKGROUND: The ongoing new coronavirus pneumonia (Corona Virus Disease 2019, COVID-19) outbreak is spreading in China, but it has not yet reached its peak. Five million people emigrated from Wuhan before lockdown, potentially representing a source of virus infection. Determining case distribution and its correlation with population emigration from Wuhan in the early stage of the epidemic is of great importance for early warning and for the prevention of future outbreaks. METHODS: The official case report on the COVID-19 epidemic was collected as of January 30, 2020. Time and location information on COVID-19 cases was extracted and analyzed using ArcGIS and WinBUGS software. Data on population migration from Wuhan city and Hubei province were extracted from Baidu Qianxi, and their correlation with the number of cases was analyzed. RESULTS: The COVID-19 confirmed and death cases in Hubei province accounted for 59.91% (5806/9692) and 95.77% (204/213) of the total cases in China, respectively. Hot spot provinces included Sichuan and Yunnan, which are adjacent to Hubei. The time risk of Hubei province on the following day was 1.960 times that on the previous day. The number of cases in some cities was relatively low, but the time risk appeared to be continuously rising. The correlation coefficient between the provincial number of cases and emigration from Wuhan was up to 0.943. The lockdown of 17 cities in Hubei province and the implementation of nationwide control measures efficiently prevented an exponential growth in the number of cases. CONCLUSIONS: The population that emigrated from Wuhan was the main infection source in other cities and provinces. Some cities with a low number of cases showed a rapid increase in case load. Owing to the upcoming Spring Festival return wave, understanding the risk trends in different regions is crucial to ensure preparedness at both the individual and organization levels and to prevent new outbreaks.

Characterisation of drug resistance-associated mutations among clinical multidrug-resistant Mycobacterium tuberculosis isolates from Hebei Province, China.

OBJECTIVES: Multidrug-resistant tuberculosis (MDR-TB) is a major public-health problem in China. However, there is little information on the molecular characterisation of clinical MDR-TB isolates in Hebei Province. METHODS: In this study, 123 MDR-TB isolates were identified in sputum cultures using traditional drug susceptibility testing. The isolates were analysed for mutations in seven genes associated with resistance to antituberculous four drugs: katG and inhA promoter for isoniazid (INH); rpoB for rifampicin (RIF); gyrA and gyrB for ofloxacin (OFLX); and rrs and eis promoter for kanamycin (KAN). All strains were genotyped by spoligotyping and 15-loci MIRU-VNTR analysis. RESULTS: A total of 39 distinct mutations were found at the seven loci in 114/123 (92.7%) MDR-TB isolates. Frequencies of INH, RIF, OFLX and KAN resistance-associated mutations were 82.1% (101/123), 83.7% (103/123), 92.1% (35/38) and 76.2% (16/21), respectively. The most prevalent mutations involved in resistance were: Ser315Thr in katG (70/123; 56.9%) and C(-15)T in inhA (15/123; 12.2%) for INH; Ser531Leu in rpoB (72/123; 58.5%) for RIF; Asp94Gly in gyrA (10/38; 26.3%) for OFLX; and A1401G in rrs (12/21; 57.1%) for KAN. Four novel gyrB mutants (Leu442Leu, Ser447Phe, Asn499Thr and Ala504Val) were identified. Mutations in katG, rpoB (or both) and the inhA promoter showed a sensitivity of 75.6% and specificity of 97.0% for detection of MDR-TB. DNA sequencing of the seven loci was 57.1% sensitive and 91.0% specific for prediction of XDR-TB isolates. CONCLUSION: These results may be of value in rapid molecular detection of MDR- and XDR-TB isolates in clinical samples in Hebei Province.

The roles of rpsL, rrs, and gidB mutations in predicting streptomycin-resistant drugs used on clinical Mycobacterium tuberculosis isolates from Hebei Province, China.

Streptomycin (STR) is a component of first-line drugs used to treat multidrug-resistant tuberculosis. The purpose of this study was to investigate the proportion and type of mutations in Mycobacterium tuberculosis isolates resistant to STR and their relationship with the STR-resistant phenotype and with the epidemiological molecular model of the isolates. A total of 302 clinical isolates, including 215 STR-resistant and 87 STR-susceptible isolates, were characterized using the proportion method with Lowenstein-Jensen medium. The genes rpsL, rrs and gidB were screened for mutations using DNA sequencing methodology. All strains were genotyped using the spoligotyping technique. Mutations in rpsL and in rrs were observed in 63.3% and 15.8% of the STR-resistance isolates, respectively. The most prevalent mutations were the Lys43Arg substitution in the rpsL gene and the A514C change in the rrs gene. Ten novel mutations were identified in gidB. These novel mutations might be new potential markers for predicting STR-resistance in clinical Mycobacterium tuberculosis isolates. Mutations in rpsL, rrs, and gidB had a sensitivity of 84.2% and a specificity of 77.0% for the detection of STR-resistance isolates. The Beijing lineage strains were associated with the rpsL mutation Lys43Arg (P = 0.051), as well as the dual gidB mutations Glu92Asp and Ala205Ala (P < 0.001). Our study suggested that rpsL and rrs can act as useful genetic markers for predicting STR-resistance, and gidB polymorphisms play an important role in STR-resistant clinical Mycobacterium tuberculosis isolates from Hebei, China.