Microbiology and Immunology最新文献

Lactiplantibacillus brownii is a new species of lactic acid bacteria discovered in sauerkraut in Russia, first reported in 2023. We previously isolated L. brownii strain MH-1 (MH-1) from homemade pickled Chinese cabbage in Japan and reported that MH-1 prolonged healthspan and improved stress resistance in Caenorhabditis elegans. In the present study, we investigated the effect of feeding MH-1 on resistance to infections in C. elegans. MH-1 failed to increase its resistance to infection with Staphylococcus aureus subsp. aureus (SA) and Salmonella enterica (SE) at the adult stage. However, MH-1 feeding at the larval stage remarkably increased the survival rate of worms infected with SA, but not with SE. Genes related to the innate immune response were significantly upregulated by MH-1 feeding at the larval stage compared with those of the control group. A survival assay using loss-of-function mutants revealed that resistance to SA infection conferred by MH-1 feeding during the larval stage requires daf-16 and pmk-1. These results suggest that MH-1 feeding at the larval stage likely confers resistance to SA infection by enhancing host immunity via the insulin/insulin-like growth factor 1 signaling and p38 mitogen-activated protein kinase pathways.

Reverse genetics enables the generation of recombinant viruses; however, conventional approaches using full-length cDNA cloned into bacterial artificial chromosomes or plasmids are time-consuming and technically challenging. While the circular polymerase extension reaction (CPER) has been applied to RNA viruses, it has not been used for DNA viruses. Here, we successfully applied CPER to generate infectious recombinant adenoviruses (AdVs) of two serotypes. The resulting viruses replicated comparably to parental strains, and replication was confirmed by immunostaining. These findings demonstrate that CPER is a rapid and efficient platform for reverse genetics of DNA viruses and may accelerate AdV research and therapeutic development.

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia, a highly contagious respiratory disease. It is classified into two biovars on the basis of NAD requirement for growth: biovar 1 (NAD-dependent) and biovar 2 (NAD-independent). Biovar 1 consists of 17 serovars (1−12 and 15−19) and biovar 2 has 8 serovars (2, 4, 7, 9, 11, 13, 14, and 17). Several virulence factors are responsible for the pathogenesis of A. pleuropneumoniae, particularly Apx toxins, capsular polysaccharides, lipopolysaccharides, and membrane proteins. In this review, the current knowledge of biovars, serovars, epidemiology, virulence factors of A. pleuropneumoniae as well as laboratory diagnosis and vaccines are summarized.

Dengue fever poses a grave threat to public health worldwide, claiming numerous fatalities each year with tropical regions being particularly hard hit by dengue outbreaks. The multiple-epitope construct is tailored to the dengue virus's geographical prevalence and the genetics of the Pakistani population. 14 experimentally validated MHC-I and MHC-II epitope sequences, were employed to generate the variants by taking into account the conservancy in all serotypes. Subsequently, the binding affinities of each derived variant against the human leukocyte antigen alleles most common among the Pakistani population were analyzed. A total of three epitopes, two Class-I (GTSGSPIINR and RSWNTGFDW), and one Class-II (ILAPTRVVAAEMEEA), with a combined Pakistani population coverage of more than 73%, together with five linear B cell epitopes were used to create six possible multi-epitope fusion constructs. The molecular docking analysis indicated that two constructs demonstrated notable binding affinities for the most abundant HLA-A*11:01 in Pakistan. Additionally, molecular dynamics (MD) simulations identified one of the constructs as a promising therapeutic candidate. The vaccine construct selected from this analysis could aid in future vaccine design for the dengue virus following further in vitro test validation and in vivo studies to investigate its immune protection capacity.

We investigated the receptor usage of the hepatitis C virus (HCV) genotype 3a S310 strain using cell culture–derived HCV (HCVcc) and trans-complemented HCV particles (HCVtcp). Infection by HCV strains of genotypes 1, 2, and 3 was inhibited by anti-CD81 antibody. By contrast, anti–claudin (CLDN)1 antibody reduced infection by the genotype 1b TH strain and genotype 2a JFH-1 strain but had no effect on the S310 strain (genotype 3a). Moreover, CLDN1-knockout cells remained permissive to infection with a chimeric HCVcc bearing the S310 envelope in a JFH-1 backbone. In CLDN1-deficient cells, infection by HCVtcp derived from the S310 strain was significantly reduced by treatment with anti–claudin-6 (CLDN6) antibody or knockdown of CLDN6 mRNA, suggesting that the S310 strain utilizes CLDN6 as an alternate entry factor. Further analyses revealed that HCVtcp of genotype 4a (ED43 strain) and genotype 6a (HK6a strain) also infected CLDN1-deficient cells. These findings provide new insights into CLDN usage by diverse HCV genotypes and raise the possibility that CLDN tropism may affect viral entry, infection efficiency, and pathogenesis.