For a paper in PLOS One, researchers at Weill Cornell Medicine and elsewhere consider the relationship between SARS-CoV-2 viral load and COVID-19 mortality rates in New York City during the first pandemic wave. The team used RT-PCR test cycle threshold values to estimate viral load over time in more than 6,900 individuals who sought COVID-19 treatment in emergency departments at half a dozen NYC hospitals from mid-March to mid-May of 2020. There, the authors saw higher-than-usual viral loads in hospitalized patients with enhanced mortality, while both viral loads and mortality rates waned by May. "If our findings are confirmed in other studies, the identification of increasing viral load among hospitalized patients could potentially be used as an early warning signal for an impending increase in severe cases of COVID-19 and thus inform decisions regarding closures of businesses and schools and allocation of resources for hospitals," the authors suggest. "Conversely, identification of declining viral loads among hospitalized patients could potentially be used to help guide re-openings."
In PLOS Genetics, researchers from the Chinese Academy of Agricultural Sciences and other centers in China share findings from a genomic and transcriptomic study of skeletal muscle features across more than two dozen different developmental stages in pigs from a local Tongcheng pig breed known for relatively slow growth, high quality meat, higher fat content and environmental adaptations, along with pigs from commercial Landrace breeds, in which large size and swift have been under strong selection. "We analyzed the molecular characteristics, gene co-expression, and interaction network of skeletal muscle development, and compared the similarity and differences between Landrace and Tongcheng pigs," the team explains. "The integrative analysis of transcriptome and genome revealed the genetic regulation of coding and non-coding RNAs, such as SATB2 and XLOC_036765, in skeletal muscle development and diversity in vivo and in vitro."
Farmed mink may become re-infected with SARS-CoV-2, according to a PLOS Pathogens study. Using blood testing, throat swabs, RT-PCR, and viral whole-genome sequencing, a University of Copenhagen-led team tracked SARS-CoV-2 infections on a farm with about 15,00 adult or young animals, where mink were not culled when an outbreak was identified. There, around three-quarters of animals were initially positive for SARS-CoV-2 RNA and all the mink appeared to have antibodies against it, the researchers note. While mink appeared to retain antibodies after several weeks, based on testing in 300 animals, they report, reinfections began occurring within less than three months — infections that involved a version of SARS-CoV-2 that had undergone only silent genome sequence changes and was expected to produce the same antigens. "The antibody levels in mink during this second wave of infection were much higher than observed after the initial infection," the authors write, noting that "the initial round of infection in mink was insufficient to confer protection against re-infection."