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PLOS Papers on Telomeres and Copy Number, Gallbladder Typhus, Cat Hepadnavirus

In PLOS Genetics, researchers from the National Cancer Institute, Brigham and Women's Hospital, and the Broad Institute explore the relationship between clonal somatic copy number alterations (SCNA) and genetically predicted telomere length in peripheral blood leukocyte cells, based on genotyping array profiles for more than 431,500 UK Biobank participants. Using polygenic risk scores as a predictor of telomere length, and a SCNA value established with array-based haplotype and intensity information, the team saw an apparent association between variants implicated in enhanced telomere length and the presence of autosomal clonal SCNA events, which turned up in 3.5 percent of individuals considered. "Our population-based examination of [genetically-predicted telomere length] and SNAs suggests inherited components of telomere length do not preferentially impact autosomal SCNA event location or copy numbers status," the authors note, "but rather likely influence cellular replicative potential."

A team in Vietnam, the UK, and Nepal reports on Salmonella Typhi features found in "Typhoid Mary"-like carrier individuals with ongoing gallbladder colonization by the typhoid fever-causing microbe. As they report in PLOS Pathogens, the investigators did whole-genome sequencing on two dozen S. Typhi isolates obtained from bile samples from individuals with known gallbladder carriage of the bug, comparing them to sequences from almost 100 S. Typhi isolates found in the blood of individuals with acute typhoid infections. Although the gallbladder bugs came from the same genotypes as those found in acute infections, the data pointed to an uptick in genetic diversity and non-synonymous mutation frequencies in isolates from the gallbladder. "Our work shows that selective pressures asserted by the hostile environment of the human gallbladder generate new antigenic variants," they write, "and raises questions regarding the role of carriage in the epidemiology of typhoid fever."

Investigators in Thailand take a look at a domestic cat hepadnavirus (DCH) related to human hepatitis B virus (HBV) for a paper in PLOS One. The cat virus, which was initially reported in an immunocompromised cat during a transcriptomics-based leukemia study in Australia, has since been sequenced in a handful of cats from Australia, Italy, or Malaysia, the team says. For the new study, the authors used PCR-based screening, quantitative PCR, immunohistochemistry, transmission electron microscopy, and other post-mortem analyses to search for and characterize DCH in blood samples from 209 randomized domestic cats and 15 cats with liver disease, treated at veterinary hospitals in Thailand between December, 2016 and late 2019. Based on genetic data generated for the DCH isolates found in a small subset of the cats, they conclude that "genetic diversity and novel genetic clades of DCH are now circulating in the cat population in Thailand."