Identification of the First C1 Subgenotype of Enterovirus 71 in Mainland of China in a Retrospective Study

The C4 sub-genotype of Enterovirus 71(EV71) is identified as the most dominant sub-genotype circulating in Chinese mainland since 1998, while the circulation situation of EV71 before 1998 is not well established due to insufficient experimental data. The C1 sub-genotype of EV71 has not been reported in Chinese mainland by now. Based on AFP surveillance system of the mainland of China, this study performed a retrospective study of AFP cases for 1985-1999༚A strain of EV-A71 C1 sub-genotype was found. To our knowledge, this strain (SD92-41) is the first C1 sub-genotype reported in Chinese mainland. This study proves that the C1 gene subtype also appeared in Chinese mainland, but it is not clear whether it is an imported or a local epidemic strain. With sufficient information from retrospective studies, the source of the SD92-41 strain will be identified, and the prevalence of EV-A71 in Chinese mainland before 1998 will be clearer.

Fourier Transform Infrared Spectroscopy for Typing Burkholderia cenocepacia ET12 Isolates

Respiratory infections due to Burkholderia cenocepacia , particularly the ET12 epidemic strain, are considered sentinel events for persons with cystic fibrosis, as they are often associated with person-to-person transmission and accelerated decline in lung function and early mortality. Current typing methods are generally only available at reference centers, with long turn-around-times, which can affect the identification of outbreaks and critical patient triage.

Evaluation of Safety and Protective Efficacy of a waaJ and spiC Double Deletion Korean Epidemic Strain of Salmonella enterica Serovar Gallinarum

With an aim to develop a highly attenuated and strongly immunogenic distinguishable vaccine candidate, a waaJ (a gene involved in the synthesis of lipopolysaccharide) and spiC (a virulence gene) double deletion Korean epidemic strain of S. enterica ser. Gallinarum (SG005) was constructed. Our results showed that the growth and biochemical characteristics were not altered by this double deletion. The double deletion strain contained dual markers. One was a bacteriological marker (rough phenotype) and the other was a serological marker helping distinguish infected chickens from vaccinated chickens. The double deletion strain showed good genetic stability and reduced resistance to environmental stresses in vitro; furthermore, it was extremely safe and highly avirulent in broilers. Single intramuscular or oral immunization of 7-day-old broilers with the double deletion strain could stimulate the body to produce antibody levels similar to the conventional vaccine strain SG9R. In addition, against a lethal wild-type challenge, it conferred effective protection that was comparable to that seen in the group vaccinated with SG9R. In conclusion, this double deletion strain may be an effective vaccine candidate for controlling S. enterica ser. Gallinarum infection in broilers.

Characterization of Canine Influenza Virus A (H3N2) Circulating in Dogs in China from 2016 to 2018

Avian H3N2 influenza virus follows cross-host transmission and has spread among dogs in Asia since 2005. After 2015–2016, a new H3N2 subtype canine influenza epidemic occurred in dogs in North America and Asia. The disease prevalence was assessed by virological and serological surveillance in dogs in China. Herein, five H3N2 canine influenza virus (CIV) strains were isolated from 1185 Chinese canine respiratory disease samples in 2017–2018; these strains were on the evolutionary branch of the North American CIVs after 2016 and genetically far from the classical canine H3N2 strain discovered in China before 2016. Serological surveillance showed an HI antibody positive rate of 6.68%. H3N2 was prevalent in the coastal areas and northeastern regions of China. In 2018, it became the primary epidemic strain in the country. The QK01 strain of H3N2 showed high efficiency in transmission among dogs through respiratory droplets. Nevertheless, the virus only replicated in the upper respiratory tract and exhibited low pathogenicity in mice. Furthermore, highly efficient transmission by direct contact other than respiratory droplet transmission was found in a guinea pig model. The low-level replication in avian species other than ducks could not facilitate contact and airborne transmission in chickens. The current results indicated that a novel H3N2 virus has become a predominant epidemic strain in dogs in China since 2016 and acquired highly efficient transmissibility but could not be replicated in avian species. Thus, further monitoring is required for designing optimal immunoprophylactic tools for dogs and estimating the zoonotic risk of CIV in China.

Phylogenetic Analysis and Genome-Wide Association Study Applied to an Italian Listeria monocytogenes Outbreak

From May 2015 to March 2016, a severe outbreak due to Listeria monocytogenes ST7 strain occurred in Central Italy and caused 24 confirmed clinical cases. The epidemic strain was deeply investigated using whole-genome sequencing (WGS) analysis. In the interested area, the foodborne outbreak investigation identified a meat food-producing plant contaminated by the outbreak strain, carried by pork-ready-to-eat products. In the same region, in March 2018, the epidemic strain reemerged causing one listeriosis case in a 10-month-old child. The aim of this study was to investigate the phylogeny of the epidemic and reemergent strains over time and to compare them with a closer ST7 clone, detected during the outbreak and with different pulsed-field gel electrophoresis (PFGE) profiles, in order to identify genomic features linked to the persistence and the reemergence of the outbreak. An approach combining phylogenetic analysis and genome-wide association study (GWAS) revealed that the epidemic and reemergent clones were genetically closer to the ST7 clone with different PFGE profiles and strictly associated with the pork production chain. The repeated detection of both clones was probably correlated with (i) the presence of truly persistent clones and the repeated introduction of new ones and (ii) the contribution of prophage genes in promoting the persistence of the epidemic clones. Despite that no significant genomic differences were detected between the outbreak and the reemergent strain, the two related clones detected during the outbreak can be differentiated by transcriptional factor and phage genes associated with the phage LP-114.

Emergence of dengue virus serotype 2 in Mauritania and molecular characterization of its circulation in West Africa

The number of sporadic and epidemic dengue fever cases have reportedly been increasing in recent years in some West African countries, such as Senegal and Mali. The first epidemic of laboratory-confirmed dengue occurred in Nouakchott, the capital city of Mauritania situated in the Saharan desert, in 2014. On-site diagnosis of dengue fever was established using a rapid diagnostic test for dengue. In parallel, the presence of Aedes aegypti mosquitoes in the city was confirmed. The initial diagnosis was confirmed by RT-PCR, which showed that all samples from the 2014 dengue epidemic in Nouakchott were dengue virus serotype 2 (DENV-2). The whole genome or envelope protein gene of these strains, together with other DENV-2 strains obtained from travelers returning from West African countries to France between 2016 and 2019 (including two Mauritanian strains in 2017 and 2018), were sequenced. Phylogenetic analysis suggested a recent emergence of an epidemic strain from the cosmopolitan genotype belonging to West African cosmopolitan lineage II, which is genetically distinct from African sylvatic genotype. The origin of this DENV-2 lineage is still unknown, but our data seem to suggest a recent and rapid dispersion of the epidemic strain throughout the region. More complete genome sequences of West African DENV-2 are required for a better understanding of the dynamics of its circulation. Arboviral surveillance and outbreak forecasting are urgently needed in West Africa.

Interleukin‑17A Contributes to Bacterial Clearance in a Mouse Model of Streptococcal Toxic Shock-Like Syndrome

Streptococcus suis (S. suis), an emerging zoonotic pathogen, can cause streptococcal toxic shock-like syndrome (STSLS) in humans with high mortality. STSLS is characterized by high bacterial burden, an inflammatory cytokine storm, multi-organ dysfunction, and ultimately acute host death. Although it has been found that a significantly high level of IL-17A was induced in an NLRP3-dependent manner during STSLS development, the role of IL-17A on S. suis STSLS remains to be elucidated. In this study, we found that the epidemic strain SC 19 caused a significantly higher level of IL-17A than the non-epidemic strain P1/7. In addition, higher bacterial burden was observed from SC 19-infected il17a–/– mice than il17a+/+ mice, although acute death, tissue injury and inflammatory cytokines storm were observed in both types of mice. Furthermore, compared with il17a+/+ mice, the level of neutrophils recruitment was lower in il17a–/– mice, and the levels of induced antimicrobial proteins, such as CRAMP, S100A8 and lipocalin-2, were also decreased in il17a–/– mice. In conclusion, this study demonstrated that IL-17A does not contribute to the severe inflammation, although it may play a minor role for bacterial clearance by inducing antimicrobial proteins and promoting neutrophil recruitment during STSLS.

Identification of the First C1 Subgenotype of Enterovirus 71 in Mainland of China in a Retrospective Study

The C4 subgenotype of EV71 is identified as the most dominant subgenotype circulating in Chinese mainland since 1998, while the circulation situation of EV71 before 1998 is not well established due to insufficient experimental data. The C1 subgenotype of EV71 has not been reported in Chinese mainland by now. Based on AFP surveillance system of the mainland of China, this study performed a retrospective study of AFP cases for 1985-1999：A strain of EV-A71 C1 subgenotype was found. To our knowledge, this strain (SD92-41) is the first C1 subgenotype reported in Chinese mainland. This study proves that the C1 gene subtype appeared in Chinese mainland, but it is not clear whether it is an imported or a local epidemic strain. With sufficient information from retrospective studies, the source of the SD92-41 strain will be identified, and the prevalence of EV-A71 in Chinese mainland before 1998 will be clearer.