Biology subjects

Nichols, F.

Publications and source records attributed to Nichols, F..

2 recordsLinked to original sources

bioRxiv2024

Inhibition of SARS-CoV-2 infection by Porphyromonas gingivalis and the oral microbiome

The COVID-19 pandemic persists despite the availability of vaccines, and it is therefore crucial to develop new therapeutic and preventive approaches. In this study, we investigated the potential role of the oral microbiome in SARS-CoV-2 infection. Using an in vitro SARS-CoV-2 pseudovirus infection assay, we found a potent inhibitory effect exerted by Porphyromonas gingivalis on SARS-CoV-2 infection mediated by known P. gingivalis compounds such as phosphoglycerol dihydroceramide (PGDHC) and gingipains as well as by unknown bacterial factors. We found that the gingipain-mediated inhibition of infection is likely due to cytotoxicity, while PGDHC inhibited virus infection by an unknown mechanism. Unidentified factors present in P. gingivalis supernatant inhibited SARS-CoV-2 likely via the fusion step of the virus life cycle. We addressed the role of other oral bacteria and found certain periodontal pathogens capable of inhibiting SARS-CoV-2 pseudovirus infection by inducing cytotoxicity on target cells. In the human oral cavity, we observed the modulatory activity of oral microbial communities varied among individuals in that some saliva-based cultures were capable of inhibiting while others were enhancing infection. These findings contribute to our understanding of the complex relationship between the oral microbiome and viral infections, offering potential avenues for innovative therapeutic strategies in combating COVID-19.

microbiology↗

bioRxiv2023

The Vacant Niche Revisited: Using Negative Results to Refine the Limits of Habitability

To define the boundaries of habitability, biologists often search for highly specialized organisms in extreme environments. However, negative life detections--when a method is unable to detect microorganisms in a given setting--are just as important to constrain the environmental limits of life on Earth. In turn, these limits inform the selection of targets for life detection on other worlds. We performed a comprehensive, though non-exhaustive, literature search for negative life detections in polyextreme environments. We then catalogued the physicochemical conditions at these sites to further understand the habitability limits for life on Earth and the effects of multiple stressors on habitability. Using multivariate statistical techniques, our study searched for combinations of environmental parameters where extremes support or inhibit life. Our search raised several methodological and analytical considerations relevant to life detection studies in extreme environments. Incomplete documentation of environmental factors and experimental protocol limitations in the extreme environment literature complicated our analyses. This demonstrates the need to report negative results, particularly in life detection experiments, and the potential value for standardized reporting protocols. Exploring the range of results possible from life-detection methodologies is key to constrain the limits of life on Earth and informs our search for life elsewhere.

microbiology↗