Swine In China Research Articles

Development and application of a colloidal-gold immunochromatographic strip for detecting Getah virus antibodies

Getah virus (GETV) is a re-emerging mosquito-borne alphavirus that is highly pathogenic, mainly to pigs and horses. There are no vaccines or treatments available for GETV in swine in China. Therefore, the development of a simple, rapid, specific, and sensitive serological assay for GETV antibodies is essential for the prevention and control of GETV. Current antibody monitoring methods are time-consuming, expensive, and dependent on specialized instrumentation, and these features are not conducive to rapid detection in clinical samples. To address these problem, we developed immunochromatographic test strips (ICTS) using eukaryotically expressed soluble recombinant p62-E1 protein of GETV as a labelled antigen, which has good detection sensitivity and no cross-reactivity with other common porcine virus-positive sera. The ICTS is highly compatible with IFA and ELISA and can be stored for 1 month at 37 °C and for at least 3 months at room temperature. Hence, p62-E1-based ICTS is a rapid, accurate, and convenient method for rapid on-site detection of GETV antibodies.Key points• We established a rapid antibody detection method that can monitor GETV infection• We developed colloidal gold test strips with high sensitivity and specificity• The development of colloidal gold test strips will aid in the field serologic detection of GETV

Occurrence and characteristics of blaOXA-181-carrying Klebsiella aerogenes from swine in China

Klebsiella aerogenes is a largely understudied opportunistic pathogen that can cause sepsis and lead to high mortality rates. In this study, we reported the occurrence of carbapenem-resistant blaOXA-181-carrying Klebsiella aerogenes from swine in China and elucidate their genomic characteristics. A total of 126 samples, including 109 swine fecal swabs, 14 environmental samples, and three feed samples were collected from a pig farm in China. The samples were enriched with LB broth culture and then inoculated into MacConkey agar plates for bacterial isolation. After PCR detection of carbapenemases genes, the blaOXA-181-carrying isolates were subjected to antimicrobial susceptibility testing, and whole-genome sequence analysis. Four Klebsiella aerogenes isolates carrying the blaOXA-181 gene were obtained from swine faecal samples. All the 4 strains were belonged to ST438. The blaOXA-181 genes were located in IncX3-ColKP3 hybrid plasmids with the core genetic structure of IS26-ΔIS3000-ΔISEcp1-blaOXA-181-ΔlysR-ΔereA-ΔrepA-ISKpn19-tinR-qnrS1-ΔIS2-IS26, which suggests the potential for horizontal transfer and further dissemination of this resistance gene among Enterobacteriaceae and other sources. This study represents the first instance of OXA-181-producing K. aerogenes being identified from swine faeces in China. It is crucial to maintain continuous monitoring and ongoing attention to the detection of K. aerogenes carrying blaOXA-181 and other resistance genes in pigs.

Identification of a Novel IncHI1B Plasmid in MDR Klebsiella pneumoniae 200 from Swine in China.

Multidrug-resistant (MDR) Klebsiella pneumoniae poses a seriously threat to public health. The aim of this study was to better understand the genetic structure of its plasmids and chromosomes. The whole-genome sequence of K. pneumoniae 200 isolated from the liver of a swine with diarrhea in China was determined using PacBio RS II and Illumina MiSeq sequencing. The complete sequences of the chromosomal DNA and the plasmids were analyzed for the presence of resistance genes. The phylogenetic trees revealed that K. pneumoniae 200 displayed the closest relationship to a human-associated K. pneumoniae strain from Thailand. K. pneumoniae 200 contained two plasmids, pYhe2001 and pYhe2002, belonging to the incompatibility groups IncH-HI1B and IncF-FIA. The plasmid pYhe2001 was a novel plasmid containing four types of heavy metal resistance genes and a novel Tn6897 transposon flanked by two copies of IS26 at both ends. Mixed plasmids could be transferred from K. pneumoniae 200 to Escherichia coli DH5α through transformation together. This study reported the first time a novel plasmid pYhe2001 from swine origin K. pneumoniae 200, suggesting that the plasmids may act as reservoirs for various antimicrobial resistance genes and transport multiple resistance genes in K. pneumoniae of both animal and human origin.

Divergent Viruses Discovered in Swine Alter the Understanding of Evolutionary History and Genetic Diversity of the Respirovirus Genus and Related Porcine Parainfluenza Viruses.

ABSTRACTParamyxoviridae is a rapidly growing family of viruses, whose potential for cross-species transmission makes it difficult to predict the harm of newly emerging viruses to humans and animals. To better understand their diversity, evolutionary history, and co-evolution with their hosts, we analyzed a collection of porcine parainfluenza virus (PPIV) genomes to reconstruct the species classification basis and evolutionary history of the Respirovirus genus. We sequenced 17 complete genomes of porcine respirovirus 1 (also known as porcine parainfluenza virus 1; PPIV-1), thereby nearly tripling the number of currently available PPIV-1 genomes. We found that PPIV-1 was widely prevalent in China with two divergent lineages, PPIV-1a and PPIV-1b. We further provided evidence that a new species, porcine parainfluenza virus 2 (PPIV-2), had recently emerged in China. Our results pointed to a need for revising the current species demarcation criteria of the Respirovirus genus. In addition, we used PPIV-1 as an example to explore recombination and diversity of the Respirovirus genus. Interestingly, we only detected heterosubtypic recombination events between PPIV-1a and PPIV-1b with no intrasubtypic recombination events. The recombination hotspots highlighted a diverse geography-dependent genome structure of paramyxovirus infecting swine in China. Furthermore, we found no evidence of co-evolution between respirovirus and its host, indicating frequent cross-species transmission. In summary, our analyses showed that swine can be infected with a broad range of respiroviruses and recombination may serve as an important evolutionary mechanism for the Respirovirus genus’ greater diversity in genome structure than previously anticipated.IMPORTANCE Livestock have emerged as critically underrecognized sources of paramyxovirus diversity, including pigs serving as the source of Nipah virus (NiV) and swine parainfluenza virus type 3, and goats and bovines harboring highly divergent viral lineages. Here, we identified a new species of Respirovirus genus named PPIV-2 in swine and proposed to revise the species demarcation criteria of the Respirovirus genus. We found heterosubtypic recombination events and high genetic diversity in PPIV-1. Further, we showed that genetic recombination may have occurred in the Respirovirus genus which may be associated with host range expansion. The continued expansion of Respirovirus genus diversity in livestock with relatively high human contact rates requires enhanced surveillance and ongoing evaluation of emerging cross-species transmission threats.

Characterisation of novel Tn7-derivatives and Tn7-like transposon found in Proteus mirabilis of food-producing animal origin in China

This study aimed to clarify the characteristics of Tn7-derivatives transposons in MDR Proteus mirabilis strains isolated from anal swabs of chicken and swine in China from 2015-2020. The Tn7 tnsA gene was screened in 207 P. mirabilis isolates by polymerase chain reaction (PCR). These strains were subjected to antimicrobial susceptibility testing. Illumina Hiseq (200×coverage) was used for genome sequencing. Transposon maps were completed by PCR and Sanger sequencing and analysed by BLAST. The Tn7 tnsA gene was detected in 21 strains by PCR. Eight novel Tn7-derivatives, named Tn6667, Tn6668, Tn6669, Tn6670, Tn7095, Tn7096, Tn7097 and Tn7098, were characterised. Three types of hybrid class 2/1 integrons were found at the right end of Tn7 derivatives. A novel Tn7-like transposon Tn6666 with an active integrase gene intI2, whose transposition module shows 93% nucleotide identity to the corresponding region of Tn7, was characterised in three strains. Tn6666 is also found next to Tn7097 or Tn7098 in the chromosomes of two clonally related P. mirabilis strains. The number of resistance genes carried by the novel transposons varied from 1 to 18. A novel variant of class A extended-spectrum beta-lactamase gene, blaPER-16, with eight base substitutions compared with blaPER-12, was harboured by Tn7098. Our study characterised diverse novel Tn7-derivatives and a new Tn7-like transposon in P. mirabilis. An active integrase gene intI2 might promote the diversification of Tn7-like transposons. More attention should be paid to the prevalence and evolution of Tn7-derivatives and Tn7-like transposons and antimicrobial resistance genes they carry.

The construction and immunogenicity analyses of a recombinant pseudorabies virus with porcine circovirus type 3 capsid protein co-expression

Porcine circovirus-associated diseases (PCVADs) and pseudorabies (PR) are highly contagious and economically significant diseases of swine in China. Porcine circovirus type 3 (PCV3) is an emerging swine pathogen of PCVAD. Currently, no PCV3 vaccine is commercially available, and the epidemic caused by it is still spreading worldwide. In this study, we used the PRV variant strain HNX as the parental virus to construct recombinant PRV with TK/gE gene deletion and capsid (Cap) protein co-expression, named HNX-ΔTK/ΔgE-ORF2. The results revealed that PCV3 Cap protein can be detected in HNX-ΔTK/ΔgE-ORF2-infected PK-15 cells by both western blotting and immunofluorescence assays. Vaccination with HNX-ΔTK/ΔgE-ORF2 did not cause pruritus, ruffled fur, systemic infection, or inflammation (without high expression of interleukin-6 (IL-6) and granulocyte colony-stimulating factor (G-CSF) in plasma). Furthermore, HNX-ΔTK/ΔgE-ORF2 immunization induced an anti-Cap specific antibody, activated a PRV-specific cellular immune response, and provided 100 % protection to mice against the challenge of the virulent HNX strain. Thus, HNX-ΔTK/ΔgE-ORF2 appears to be a promising vaccine candidate against PRV and PCV3 for the control of the PRV variant and PCV3.

Prevalence of Chlamydia in Pigs in China from 1985 to 2020: A Systematic Review and Meta-Analysis.

Chlamydia is a small gram-negative (G-) microorganism that can be dangerous to human and animals. In this study, we conducted a systematic review and meta-analysis of Chlamydia infection in swine in China. From PubMed, ScienceDirect, Chinese Web of knowledge (CNKI), VIP Chinese journal database, and Wanfang database, we collected a total of 72 publications reported in 1985-2020. The prevalence of Chlamydia was 22.48% in China. In the sampling year subgroup, the prevalence after 2011 was the highest (26.14%). In southern China, the prevalence was 30.97%. By contrast, the prevalence in northern China was only 10.79%. Also the difference was significant (p < 0.05). In the provincial level, Hubei had the highest rate of 36.23%. Boars had a higher prevalence (29.47%). The prevalence of Chlamydia detection in pigs with reproductive disorders (21.86%) was higher than that without reproductive disorders. Among the three age groups, finishing pigs (21.43%) had the highest prevalence. The prevalence in large-scale farmed pigs (28.58%) was the highest in the subgroup of feeding methods. The prevalence in farms was 24.29%, which was the highest in the survey areas. The prevalence in spring was the highest with 40.51%. Other methods had the highest prevalence (39.61%) than enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination assay. The prevalence of Chlamydia psittaci 18.41% was lower than the prevalence of Chlamydia abortus (41.35%). We also analyzed the impact of different climate factor subgroups (rainfall, temperature, and humidity) on the probability of pigs suffering from the disease. The results showed that Chlamydia was widespread in pigs in China. We suggest that we should strengthen the detection of Chlamydia in the semen of breeding pigs and pigs with reproductive disorders, and reasonably control the environment of large-scale pig farms, so as to reduce further infection of Chlamydia in pigs.

A Novel Structure Harboring blaCTX-M-27 on IncF Plasmids in Escherichia coli Isolated from Swine in China.

The aim of this study was to elucidate the prevalence of blaCTX-M-27-producing Escherichia coli and transmission mechanisms of blaCTX-M-27 from swine farms in China. A total of 333 E. coli isolates were collected from two farms from 2013 to 2016. Thirty-two CTX-M-27-positive E. coli were obtained, and all were multidrug-resistant. Pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) profiles indicated a wide range of strain types that carried blaCTX-M-27, and the sequence type ST10 predominated. Conjugation, replicon typing, S1-PFGE and hybridization experiments confirmed that 28 out of 32 CTX-M-27 positive isolates carried blaCTX-M-27 genes on plasmids F18:A-:B10 (16) and F24:A-:B1 (12).The blaCTX-M-27 genes for 24 isolates were transmitted by plasmids with sizes ranging from 40 to 155 kb. A comparative analysis with blaCTX-M-27-plasmids indicated that the tra-trb region of F24:A-:B1 plasmids was destroyed by insertion of a complex region (eight isolates) and a novel structure containing blaCTX-M-27 in the F18:A-:B10 plasmids (12 isolates). The novel structure increased the stability of the blaCTX-M-27 gene in E. coli. This study indicated that the predominant vehicle for blaCTX-M-27 transmission has diversified over time and that control strategies to limit blaCTX-M-27 transmission in farm animals are necessary.

(-)-Epigallocatechin-3-Gallate Inhibits the Life Cycle of Pseudorabies Virus In Vitro and Protects Mice Against Fatal Infection.

A newly emerged pseudorabies virus (PRV) variant with enhanced pathogenicity has been identified in many PRV-vaccinated swine in China since 2011. The PRV variant has caused great economic cost to the swine industry, and measures for the effective prevention and treatment of this PRV variant are still lacking. (–)-Epigallocatechin-3-gallate (EGCG) exhibits antiviral activity against diverse viruses and thus in this study, we investigated the anti-PRV activity of EGCG in vitro and in vivo. EGCG significantly inhibited infectivity of PRV Ra and PRV XJ5 strains in PK15 B6 cells and Vero cells. The anti-PRV activity of EGCG was dose-dependent, and 50 μM EGCG could completely block viral infection at different multiplicities of infection. We next revealed that EGCG blocked PRV adsorption and entry to PK15 B6 cells in a dose-dependent manner, but inhibition of PRV entry by EGCG was not as efficient as its inhibition of PRV adsorption. PRV replication was suppressed in PK15 B6 cells treated with EGCG post-infection. However, EGCG did not affect PRV assembly and could promote PRV release. Furthermore, 40 mg/kg EGCG provided 100% protection in BALB/c mice challenged with PRV XJ5, when EGCG was administrated both pre- and post-challenge. These results revealed that EGCG exhibits antiviral activity against PRV mainly by inhibiting virus adsorption, entry and replication in vitro. Meanwhile, EGCG increased the survival of mice challenged with PRV. Therefore, EGCG might be a potential antiviral agent against PRV infection.

Prevalence of hepatitis E virus among swine in China from 2010 to 2019: A systematic review and meta-analysis

Hepatitis E virus (HEV) is a zoonotic pathogen that has spread worldwide. The HEV reservoir associated with livestock hepatitis E poses a huge threat to public health. Awareness of the prevalence and spatial distribution of livestock hepatitis E is valuable to prevent and control diseases caused by HEV, especially human hepatitis E infection. Currently, swine, including pigs (Sus scrofa), are recognized as the major reservoir of HEV. Therefore, we conducted a systematic review and meta-analysis to evaluate the pooled prevalence of HEV among swine in China. A total of 71 published papers on HEV infection in swine in China (including data from 49,523 animals) from January 1, 2010 to December 31, 2019 met the standard after searching five databases including the Technology Periodical Database, the Wan Fang Database, the China National Knowledge Infrastructure, PubMed, and ScienceDirect. A random effects model was used to calculate the pooled prevalence of HEV in swine. The results showed that the seroprevalence was 48.0% (95% confidence interval (CI) 39.6–56.9) and the prevalence of HEV RNA was 14.4% (95% CI 10.7–18.5). The estimated overall prevalence was 34.1% (95% CI 27.2–41.4). Central China (68.0%, 95% CI 42.2–89.1) had a significantly higher prevalence than other regions. In the publication year subgroup, the prevalence in 2016 or later (27.2%, 95% CI 19.3–36.0) was significantly lower than that in 2011 or earlier (49.0%, 95% CI 36.2–61.8). The prevalence of IgG (42.9%, 95% CI 31.7–54.6) was significantly higher than that of IgM (4.9%, 95% CI 1.6–9.7). Suckling piglets (15.6%, 95% CI 6.6–27.1) had a lower prevalence compared with that in other age groups. In all sample types, body fluids showed the highest prevalence (50.5%, 95% CI 41.7–59.3). Moreover, the pooled prevalence of HEV in boars was higher than that in sows (35.4% > 17.3%). The analysis suggested that HEV infection is common among swine in China. Further strengthening HEV testing in boars, controlling environmental pollution, and reducing the mixed feeding of different stages could contribute to reducing HEV infection in pigs in China and the risk of porcine HEV infection in humans.

R93P Substitution in the PmrB HAMP Domain Contributes to Colistin Heteroresistance in Escherichia coli Isolates from Swine.

Here, the mechanisms of colistin heteroresistance (CHR) were assessed in 12 Escherichia coli isolates from swine in China. CHR was investigated by population analysis profile tests. CHR stability was studied by culturing isolates for five overnight incubation periods in colistin-free medium. Subsequently, the mcr-1 gene and mutations in PmrAB, PhoPQ, and MgrB were screened in parental isolates and resistant subpopulations. Additionally, the expression levels of phoPQ, its target gene pagP, and its negative regulator gene mgrB, as well as pmrAB and its target genes pmrHFIJKLM and pmrC, were determined by real-time relative quantitative PCR. Eleven of the 12 isolates were confirmed to show CHR, with 17 resistant subpopulations. Also, 11 of the 17 subpopulations (64.71%) harbored point mutations in PmrB and/or PhoQ, differing from their parental isolates. However, only one stable resistant subpopulation (EPF42-4) was identified; it harbored an arginine-to-proline substitution at position 93 (R93P) within the PmrB HAMP (histidine kinase, adenylyl cyclase, methyl-binding protein, and phosphatase) domain. Compared to the pmrB expression levels in the parental isolate EPF42 and E. coli K-12 MG1655, remarkable pmrB overexpression was observed in EPF42-4, which showed upregulated pmrA, pmrK, and pmrC expression. Structural analysis demonstrated that the R93P substitution promotes conformational changes in the HAMP domain, leading to an acceleration in its signal transduction ability and the activation of PmrB expression. In conclusion, point mutations in PmrB and/or PhoQ were primarily associated with CHR. The R93P substitution resulted in the establishment of stable resistant subpopulations in E. coli showing CHR.

Whole-genome sequence analyses of Glaesserella parasuis isolates reveals extensive genomic variation and diverse antibiotic resistance determinants.

BackgroundGlaesserella parasuis (G. parasuis) is a respiratory pathogen of swine and the etiological agent of Glässer’s disease. The structural organization of genetic information, antibiotic resistance genes, potential pathogenicity, and evolutionary relationships among global G. parasuis strains remain unclear. The aim of this study was to better understand patterns of genetic variation, antibiotic resistance factors, and virulence mechanisms of this pathogen.MethodsThe whole-genome sequence of a ST328 isolate from diseased swine in China was determined using Pacbio RS II and Illumina MiSeq platforms and compared with 54 isolates from China sequenced in this study and 39 strains from China and eigtht other countries sequenced by previously. Patterns of genetic variation, antibiotic resistance, and virulence mechanisms were investigated in relation to the phylogeny of the isolates. Electrotransformation experiments were performed to confirm the ability of pYL1—a plasmid observed in ST328—to confer antibiotic resistance.ResultsThe ST328 genome contained a novel Tn6678 transposon harbouring a unique resistance determinant. It also contained a small broad-host-range plasmid pYL1 carrying aac(6’)-Ie-aph(2”)-Ia and blaROB-1; when transferred to Staphylococcus aureus RN4220 by electroporation, this plasmid was highly stable under kanamycin selection. Most (85.13–91.74%) of the genetic variation between G. parasuis isolates was observed in the accessory genomes. Phylogenetic analysis revealed two major subgroups distinguished by country of origin, serotype, and multilocus sequence type (MLST). Novel virulence factors (gigP, malQ, and gmhA) and drug resistance genes (norA, bacA, ksgA, and bcr) in G. parasuis were identified. Resistance determinants (sul2, aph(3”)-Ib, norA, bacA, ksgA, and bcr) were widespread across isolates, regardless of serovar, isolation source, or geographical location.ConclusionsOur comparative genomic analysis of worldwide G. parasuis isolates provides valuable insight into the emergence and transmission of G. parasuis in the swine industry. The result suggests the importance of transposon-related and/or plasmid-related gene variations in the evolution of G. parasuis.

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide.

The global anxiety and a significant threat to public health due to the current COVID-19 pandemic reiterate the need for active surveillance for the zoonotic virus diseases of pandemic potential. Influenza virus due to its wide host range and zoonotic potential poses such a significant threat to public health. Swine serve as a “mixing vessel” for influenza virus reassortment and evolution which as a result may facilitate the emergence of new strains or subtypes of zoonotic potential. In this context, the currently available scientific data hold a high significance to unravel influenza virus epidemiology and evolution. With this objective, the current systematic review summarizes the original research articles and case reports of all the four types of influenza viruses reported in swine populations worldwide. A total of 281 articles were found eligible through screening of PubMed and Google Scholar databases and hence were included in this systematic review. The highest number of research articles (n = 107) were reported from Asia, followed by Americas (n = 97), Europe (n = 55), Africa (n = 18), and Australia (n = 4). The H1N1, H1N2, H3N2, and A(H1N1)pdm09 viruses were the most common influenza A virus subtypes reported in swine in most countries across the globe, however, few strains of influenza B, C, and D viruses were also reported in certain countries. Multiple reports of the avian influenza virus strains documented in the last two decades in swine in China, the United States, Canada, South Korea, Nigeria, and Egypt provided the evidence of interspecies transmission of influenza viruses from birds to swine. Inter-species transmission of equine influenza virus H3N8 from horse to swine in China expanded the genetic diversity of swine influenza viruses. Additionally, numerous reports of the double and triple-reassortant strains which emerged due to reassortments among avian, human, and swine strains within swine further increased the genetic diversity of swine influenza viruses. These findings are alarming hence active surveillance should be in place to prevent future influenza pandemics.

Gulls as Sources of Environmental Contamination by Colistin-resistant Bacteria

In 2015, the mcr-1 gene was discovered in Escherichia coli in domestic swine in China that conferred resistance to colistin, an antibiotic of last resort used in treating multi-drug resistant bacterial infections in humans. Since then, mcr-1 was found in other human and animal populations, including wild gulls. Because gulls could disseminate the mcr-1 gene, we conducted an experiment to assess whether gulls are readily colonized with mcr-1 positive E. coli, their shedding patterns, transmission among conspecifics, and environmental deposition. Shedding of mcr-1 E. coli by small gull flocks followed a lognormal curve and gulls shed one strain >101 log10 CFU/g in their feces for 16.4 days, which persisted in the environment for 29.3 days. Because gulls are mobile and can shed antimicrobial-resistant bacteria for extended periods, gulls may facilitate transmission of mcr-1 positive E. coli to humans and livestock through fecal contamination of water, public areas and agricultural operations.

Recombinant pseudorabies virus expressing E2 of classical swine fever virus (CSFV) protects against both virulent pseudorabies virus and CSFV

Both classical swine fever (CSF) and pseudorabies are highly contagious, economically significant diseases of swine in China. Although vaccination with the C-strain against classical swine fever virus (CSFV) is widely carried out and severe outbreaks of CSF seldom occur in China, CSF is sporadic in many pig herds and novel sub-subgenotypes of CSFV endlessly emerge. Thus, new measures are needed to eradicate CSFV from Chinese farms. The emergence of a pseudorabies virus (PRV) variant also posed a new challenge for the control of swine pseudorabies. Here, the recombinant PRV strain JS-2012-ΔgE/gI-E2 expressing E2 protein of CSFV was developed by inserting the E2 expression cassette into the intergenic region between the gG and gD genes of the gE/gI-deletion PRV variant strain JS-2012-ΔgE/gI. The recombinant virus was stable when passaged in vitro. A single vaccination of JS-2012-ΔgE/gI-E2 via intramuscular injection fully protected against lethal challenges of PRV and CSFV. Vaccination of piglets with the recombinant JS-2012-ΔgE/gI-E2 in the presence of high levels of maternally derived antibodies (Abs) to PRV can provide partial protection against lethal challenge of CSFV. Vaccination of the recombinant PRV JS-2012-ΔgE/gI-E2 strain did not induce the production of Abs to the gE protein of PRV or to the CSFV proteins other than E2. Thus, JS-2012-ΔgE/gI-E2 appears to be a promising recombinant marker vaccine candidate against PRV and CSFV for the control and eradication of the PRV variant and CSFV.

Identification of a novel conjugative plasmid carrying the multiresistance gene cfr in Proteus vulgaris isolated from swine origin in China

The multiresistance gene cfr has a broad host range encompassing both Gram-positive and Gram-negative bacteria, and can be located on the chromosomes or on plasmids. In this study, a novel conjugative plasmid carrying cfr, designated as pPvSC3, was characterized in a Proteus vulgaris strain isolated from swine in China. Plasmid pPvSC3 is 284,528 bp in size and harbors 10 other antimicrobial resistance genes, making it a novel plasmid that differs from all known plasmids due to its unique backbone and repA gene. BLAST analysis of the plasmid sequence shows no significant homology to any known plasmid backbone, but shows high level homology to Providencia rettgeri strain CCBH11880 Contig_9, a strain isolated from surgical wound in Brazil, 2014. There are two resistance-determining regions in pPvSC3, a cfr-containing region and a multidrug-resistant (MDR) region. The cfr-containing region is flanked by IS26, which could be looped out via IS26-mediated recombination. The MDR region harbors 10 antimicrobial resistance genes carried by various DNA segments that originated from various sources. Plasmid pPvSC3 could be successfully transferred to Escherichia coli by conjugation. In summary, we have characterized a novel conjugative plasmid pPvSC3 carrying the multiresistance gene cfr and 10 other antimicrobial resistance genes, and consider that this novel type of plasmid deserves attention.

Carbapenemase-producing Enterobacteriaceae (CPE) isolated from pigs in China

Background The increasing prevalence of CPE is a global concern in public health. CPE were found to be present in livestock. Food animals act as a reservoir for NDM-producing bacteria. However, there is limited information about CPE in food animals. Here we screen the carbapenemase-producing bacteria in pig samples. Objective To investigate the prevalence of carbapenem resistance in swine from China. Methods A total of 138 rectal swabs from pigs imported from China were collected in Hong Kong between June 2017 and Oct 2018. Bacterial identification was conducted by MALDI-TOF for all isolates. Carba-NP test and disc diffusion method were performed to detect carbapenemase and determine the antibiotic susceptibility. Identification of carbapenemase gene and replicon type of plasmid, and further characterization of isolates were performed through PCR and next-generation sequencing respectively. Results Twenty-one CPE isolates including Escherichia coli (n=20) and Enterobacter cloacae (n=1) were isolated from 20 pigs, which were resistant to carbapenem (meropenem, ertapenem and imipenem). The prevalence rate of carbapenemase producers was 14 % (20/138). All isolates were positive in carba-NP test and harboured carbapenemase gene bla NDM. Two-third of IncX3 (14/21) plasmid appeared in bla NDM-producing isolates. Different resistance patterns were discovered among NDM-carrying isolates, but all of them were susceptible to fosfomycin and azithromycin. Conclusion Our data show that the prevalence of carbapenem-resistance Enterobacteriaceae among swine in China during 2017 to 2018 . It is also observed that NDM carbapenemases is still circulating in pigs over times.

Emergence and Evolution of Novel Reassortant Influenza A Viruses in Canines in Southern China.

ABSTRACTThe capacity of influenza A viruses (IAVs) to host jump from animal reservoir species to humans presents an ongoing pandemic threat. Birds and swine are considered major reservoirs of viral genetic diversity, whereas equines and canines have historically been restricted to one or two stable IAV lineages with no transmission to humans. Here, by sequencing the complete genomes of 16 IAVs obtained from canines in southern China (Guangxi Zhuang Autonomous Region [Guangxi]) in 2013 to 2015, we demonstrate that the evolution of canine influenza viruses (CIVs) in Asian dogs is increasingly complex, presenting a potential threat to humans. First, two reassortant H1N1 virus genotypes were introduced independently from swine into canines in Guangxi, including one genotype associated with a zoonotic infection. The genomes contain segments from three lineages that circulate in swine in China: North American triple reassortant H3N2, Eurasian avian-like H1N1, and pandemic H1N1. Furthermore, the swine-origin H1N1 viruses have transmitted onward in canines and reassorted with the CIV-H3N2 viruses that circulate endemically in Asian dogs, producing three novel reassortant CIV genotypes (H1N1r, H1N2r, and H3N2r [r stands for reassortant]). CIVs from this study were collected primarily from pet dogs presenting with respiratory symptoms at veterinary clinics, but dogs in Guangxi are also raised for meat, and street dogs roam freely, creating a more complex ecosystem for CIV transmission. Further surveillance is greatly needed to understand the full genetic diversity of CIV in southern China, the nature of viral emergence and persistence in the region’s diverse canine populations, and the zoonotic risk as the viruses continue to evolve.

Novel Variant of New Delhi Metallo-β-lactamase, NDM-20, in Escherichia coli.

The spread of carbapenem-resistant Enterobacteriaceae (CRE) mediated by New Delhi metallo-β-lactamase (NDM) poses a serious challenge to clinicians and has become a major public health concern. NDM has been evolving into variants that possess different hydrolysis activity toward antibiotics, so as to affect treatment strategy. In addition, very few studies on NDM variants have focused on animal-derived bacterial isolates. Our study reports a novel NDM variant, NDM-20, in an isolate of Escherichia coli CCD1 recovered from the food animal swine in China. The isolate that was assigned to ST1114, exhibited high level resistance to all β-lactams tested, including aztreonam and carbapenems. The gene of blaNDM-20 was located on an IncX3-type plasmid, surrounded by multiple insertion sequences. Sequencing analysis demonstrated that blaNDM-20 contained three point mutations at positions 262 (G→T), 460 (A→C), and 809 (G→A), compared with blaNDM-1, and just one point mutation at position 809 (G→A), relative to blaNDM-5. Functional analysis revealed that the blaNDM-20 transformant, DH5α+pHSG398/NDM-20, exhibited a higher resistance to ertapenem than that of blaNDM-1 transformant DH5α+pHSG398/NDM-1. Kinetic parameter analysis showed that NDM-20 had increased enzymatic activity against some penicillins and cephalosporins but decreased carbapenemase activity relative to NDM-5. The identification of NDM-20 further confirms the evolution and prevalence of NDM variants in bacteria of food-animal origin.

Diversity of group A rotavirus of porcine rotavirus in Shandong province China.

Porcine rotavirus (PoRV) is one of the major causes of neonatal diarrhea in swine worldwide. Multiple serotypes of PoRV have been detected in diarrhea cases of suckling and weaning pigs. To date, the prevalence and molecular characterizations of PoRV circulating in swine in Shandong province of China remains largely unknown. Two hundred and twenty-six feces samples were collected from ten farms showing diarrhea in Shandong. All the samples were tested by RT-PCR for the presence of PoRV, TGEV, or PEDV. The results showed that all farms are positive for PEDV, and 60% and 10% of the farms are positive for PoRV and TGEV respectively. PoRV was detected in 65 out of 226 (28.76%) samples collected from 1-3 months old suckling and weaning pigs, while the positive rates of the TGEV and PEDV were 2.21% and 34.96%, respectively. The present data emphasized that PoRV is an important pathogen causing diarrhea in swine in China. In addition, VP6 and VP7 genes of PoRVs were sequenced and analyzed. Phylogenetical analysis of VP6 showed that all of the five PoRVs belong to group A rotavirus, meanwhile VP7 genes belong to the G3, G5, and G9 genotypes. Moreover, G5 and G9 genotypes are the dominant genotypes. Taken together, co-infections of TGEV, PEDV, and PoRV occur in pig population in Shandong, and the multiple serotypes of PoRVs are circulating in those herds, suggesting the active surveillance and matched vaccine application.