Kitazawa, H. | bioRxiv Science

bioRxiv2024

Comparative genomic analysis of multidrug-resistant clinical isolates of Mycobacterium abscessus revealed worldwide horizontal plasmid transfer

Genetic epidemiological analysis of mobile genetic elements, such as plasmids, has rarely been carried out in Mycobacterium abscessus, regardless of its usefulness in speculating the past contact between bacteria. In this study, through whole genome sequencing analysis of clinical isolates of M. abscessus sequentially collected from the same patient, we identified a single nucleotide variant that could cause antibiotic resistance, and three plasmids (pMAB625-1, pMAB625-2 and pMAB625-3) not found in the type strain. We investigated the distribution of plasmids previously identified in M. abscessus, including pMAB625 plasmids, in 462 clinical isolates worldwide in silico. pMAB625-3 was detected in the largest number of isolates. Furthermore, phylogenetic tree analysis revealed that these plasmids transferred beyond regions and subspecies and acquired unique mutations. These results indicate that transmission of plasmids increases the genomic diversity in M. abscessus, and plasmid epidemiology is useful for estimating the past contact between bacteria.

genomics↗

bioRxiv2021

Protein-bound sialic acid in saliva contributes directly to salivary anti-influenza virus activity

The oral cavity is an entrance for respiratory viruses, such as influenza. Recently, saliva has been shown to exert both antimicrobial and antiviral activities. Thus, saliva may be a biological factor that contributes to the prevention of influenza infection. However, the actual salivary anti-influenza A virus (IAV) activity in individuals and its determinant factors are unknown. By assessing individual variations in salivary anti-IAV activity in 92 people using an established new high-throughput system in this study, we found that the anti-IAV activity varied widely between individuals and showed a significant positive correlation with protein-bound sialic acid (BSA) level ({rho}=0.473; p < 0.001). Furthermore, the anti-IAV activity of saliva with enzymatically reduced BSA content was significantly lower. These results indicate that BSA is a direct regulator of salivary anti-IAV activity and is a determinant of individual differences. Additionally, after comparing the anti-IAV activity across the groups by age, anti-IAV activity in young people (aged 5-19 years) were lower than in adults aged 20-59 years and elderly people aged 60-79 years. Our study suggests that BSA levels in saliva may be important in preventing influenza infection.

immunology↗