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The hemagglutinin (HA) gene of highly pathogenic avian influenza subtype H5 viruses has evolved into multiple clades (clades 0-9), and some clades are further divided into subclades. Of the 2 [...]

ObjectiveThis study aimed to comprehensively analyze the prevalence， virulence characteristics， and molecular typing of Listeria monocytogenes （L. monocytogenes） isolated from various food sources in Guangxi. By investigating the genetic attributes and potential transmission mechanisms of L. monocytogenes， this research contributes to our understanding of this pathogen.MethodsA total of 210 L. monocytogenes strains collected from 2002 to 2020 in Guangxi were subjected to whole genome sequencing （WGS） analysis. The study included the determination of sequence types （STs）， clonal complexes （CC）， and the presence of L. monocytogenes pathogenicity islands （LIPIs）.ResultsOf the L. monocytogenes isolates， 53.8% were traced back to meat and meat products from 2002 to 2020 in Guangxi. Among these isolates， 59.0% belonged to lineage Ⅱ. The predominant STs were ST8 and ST9. Virulence gene analysis revealed that 79.4% of isolates carried LIPI-1 genes （hly， prfA， plcA， plcB， mpl， and actA）， while 83.7% carried LIPI-2 genes （inlC， inlF， inlJ， and inlK）. Furthermore， 17.6% of isolates carried LIPI-3 genes （llsA， llsB， llsD， llsG， llsH， llsP， llsX， and llsY）.ConclusionMeat and meat products in Guangxi showed the highest prevalence of L. monocytogenes. Molecular typing results demonstrated a high genetic diversity among L. monocytogenes strains. The discriminatory power of WGS makes it a valuable tool for monitoring foodborne listeriosis outbreaks. The distribution of virulence genes indicated that L. monocytogenes of Guangxi had different degree of deletion of virulence genes， underscoring the importance of vigilance regarding highly pathogenic strains that could potentially cause foodborne outbreaks.

The global spread of H5 clade 2.3.4.4 highly pathogenic avian influenza (HPAI) viruses threatens poultry and public health. The continuous circulation of these viruses has led to their considerable genetic and antigenic evolution, resulting in the formation of eight subclades (2.3.4.4a–h). Here, we examined the antigenic sites that determine the antigenic differences between two H5 vaccine strains, H5-Re8 (clade 2.3.4.4g) and H5-Re11 (clade 2.3.4.4h). Epitope mapping data revealed that all eight identified antigenic sites were located within two classical antigenic regions, with five sites in region A (positions 115, 120, 124, 126, and 140) and three in region B (positions 151, 156, and 185). Through antigenic cartography analysis of mutants with varying numbers of substitutions, we confirmed that a combination of mutations in these eight sites reverses the antigenicity of H5-Re11 to that of H5-Re8, and vice versa. More importantly, our analyses identified H5-Re11_Q115L/R120S/A156T (H5-Re11 + 3) as a promising candidate for a broad-spectrum vaccine, positioned centrally in the antigenic map, and offering potential universal protection against all variants within the clade 2.3.4.4. H5-Re11 + 3 serum has better cross-reactivity than sera generated with other 2.3.4.4 vaccines, and H5-Re11 + 3 vaccine provided 100% protection of chickens against antigenically drifted H5 viruses from various 2.3.4.4 antigenic groups. Our findings suggest that antigenic regions A and B are immunodominant in H5 viruses, and that antigenic cartography-guided vaccine design is a promising strategy for selecting a broad-spectrum vaccine. [ABSTRACT FROM AUTHOR]

ObjectiveEstablishing the database of food-borne Salmonella typhimurium 1, 4, [5], 12∶i∶- and monophasic variant in Guangxi Zhuang Autonomous Region by investigating the drug resistance and molecular typing characteristics of the isolates in 2018.Methods124 strains of S. 1, 4, [5], 12∶i∶- from clinic samples and food samples were tested for drug sensitivity by minimum inhibitory concentration (MIC), and molecular typing by pulsed field gel electrophoresis (PFGE).ResultsOne hundred and twenty four strains of S. 1, 4, [5], 12∶i∶- were all sensitive to imipenem, but resistant to the other 13 antibiotics at different levels. The resistance rate to tetracycline was the highest (96.8%, 120/124), followed by ampicillin (95.2%, 118/124). Multidrug resistant (MDR) rate was 26.6% (33/124), and 47.1% S. 1, 4, [5], 12∶i∶- isolates were multi-resistant to ACSuT. The S. 1, 4, [5], 12∶i∶- strains were differentiated into 104 Xba I PFGE patterns with similarity of 72.9%-100%, and the dominant patterns were JPXX01.GX0114 (5 isolates) and JPXX01.GX0294 (4 isolates), all of which came from foodborne disease surveillance.ConclusionThe result indicated that the S. 1, 4, [5], 12∶i∶- isolates in Guangxi were highly resistant to penicillins and tetracyclines and drug resistance situation was not optimistic, S. 1, 4, [5], 12∶i∶- PFGE pattern were highly sporadic. It is necessary to trace the molecular origin of the isolated strains on time, which can improve ability to identify potential food-borne S. 1, 4, [5], 12∶i∶- outbreak events in sporadic cases.

H6 avian influenza virus (AIV) is one of the most prevalent AIV subtypes in the world. Our previous studies have demonstrated that H6 AIVs isolated from live poultry markets pose a potential threat to human health. In recent years, increasing number of H6 AIVs has been constantly isolated from poultry farms. In order to understand the biological characteristics of H6 AIVs in the context of farms, here, we analyzed the phylogenetic relationships, antigenicity, replication in mice and receptor binding properties of H6 AIVs isolated from farms in China between 2014 and 2018. Phylogenetic analysis showed that 19 different genotypes were formed among 20 representative H6 viruses. Notably, the internal genes of these H6 viruses exhibited complicated relationships with different subtypes of AIVs worldwide, indicating that these viruses are the products of complex and frequent reassortment events. Antigenic analysis revealed that 13 viruses tested were divided into three antigenic groups. 10 viruses examined could all replicate in the respiratory organs of infected mice without prior adaptation. Receptor binding analysis demonstrated that some of the H6 AIVs bound to both α‐2, 3‐linked glycans (avian‐type receptor) and α‐2, 6‐linked glycans (human‐type receptor), thereby posing a potential threat to human health. Together, these findings revealed the prevalence, complicated genetic evolution, diverse antigenicity, and dual receptor binding specificity of H6 AIVs in the settings of poultry farms, which emphasize the importance to continuously monitor the evolution and biological properties of H6 AIVs in nature. [ABSTRACT FROM AUTHOR]

The H7N9 influenza virus emerged in China in 2013, causing more than 1560 human infections, 39% of which were fatal. A 'cytokine storm' in the lungs of H7N9 patients has been linked to a poor prognosis and death; however, the underlying mechanism that triggers the cytokine storm is unknown. Here, we found that efficient replication of the H7N9 virus in mouse lungs activates gasdermin E (GSDME)-mediated pyroptosis in alveolar epithelial cells, and that the released cytosolic contents then trigger a cytokine storm. Knockout of Gsdme switched the manner of death of A549 and human primary alveolar epithelial cells from pyroptosis to apoptosis upon H7N9 virus infection, and Gsdme knockout mice survived H7N9 virus lethal infection. Our findings reveal that GSDME activation is a key and unique mechanism for the pulmonary cytokine storm and lethal outcome of H7N9 virus infection and thus opens a new door for the development of antivirals against the H7N9 virus. [ABSTRACT FROM AUTHOR]