Biology subjects

Frias, A.

Publications and source records attributed to Frias, A..

3 recordsLinked to original sources

bioRxiv2022

A Rapid, High Throughput, Viral Infectivity Assay using Automated Brightfield Microscopy with Machine Learning

Infectivity assays are essential for the development of viral vaccines, antiviral therapies and the manufacture of biologicals. Traditionally, these assays take 2-7 days and require several manual processing steps after infection. We describe an automated assay (AVIA), using machine learning (ML) and high-throughput brightfield microscopy on 96 well plates that can quantify infection phenotypes within hours, before they are manually visible, and without sample preparation. ML models were trained on HIV, influenza A virus, coronavirus 229E, vaccinia viruses, poliovirus, and adenoviruses, which together span the four major categories of virus (DNA, RNA, enveloped, and non-enveloped). A sigmoidal function, fit to virus dilution curves, yielded an R2 higher than 0.98 and a linear dynamic range comparable to or better than conventional plaque or TCID50 assays. Because this technology is based on sensitizing AIs to specific phenotypes of infection, it may have potential as a rapid, broad-spectrum tool for virus identification.

microbiology↗

bioRxiv2019

Spatial distribution and spread potential of sixteen Leptospira serovars in a subtropical region of Brazil

Leptospirosis is a bacterial disease that represents a major problem in animal and public health due to its high prevalence and widespread distribution. This zoonotic disease is most prevalent in tropical environments where conditions favor pathogen survival. The ecological preferences of Leptospira serovars are poorly understood, limiting our knowledge of where and when outbreaks can occur, which may result in misinformed prevention and control plans. While the disease can occur consistently in time and space in tropical regions, research on the ecology of Leptospirosis remains limited in subtropical regions. This research gap regarding Leptospira ecology brings public and veterinary health problems, impacting local economies. To fill this gap of knowledge, we propose to assess geographic and ecological features among Leptospira serovars in a subtropical area of Brazil where Leptospirosis is endemic to (i) highlight environmental conditions that facilitate or limit Leptospira spread and survival and (ii) reconstruct its geographical distribution. An ecological niche modeling framework was used to characterize and compare Leptospira serovars in both geographical and environmental space. Our results show that, despite the geographic overlap exhibited by the different serovars assessed, we found ecological divergence among their occupied ecological niches. Ecological divergences were expressed as ranges of potential distributions and environmental conditions found suitably by serovar, being Sejroe the most asymmetric. Most important predictors for the potential distribution of most serovars were soil pH (31.7%) and landscape temperature (24.2%). Identification of environmental preferences will allow epidemiologists to better infer the presence of a serovar based on the environmental characteristics of regions rather than inferences based solely on historical epidemiological records. Including geographic and ecological ranges of serovars also may help to forecast transmission potential of Leptospira in public health and the food animal practice.

epidemiology↗

bioRxiv2018

Clarification and confocal imaging of the non-human primate placental micro-anatomy

Placental function is essential for the development of the fetus, and is - in part - related to the 3D arrangement of the villous and vascular geometry. Recent advances in tissue clarification techniques allow for deep high-resolution imaging with confocal microscopy without altering the spatial characteristics of the tissue. These image stacks can be analyzed quantitatively to provide insights regarding the villous and vascular micro-anatomy as well as the interrelationships between the two. However, such analyses require optimization of the tissue preparation, immuno-labeling, and clarification protocol in order to provide reliable results suitable for the detection of subtle differences in pathologic pregnancies. Placental and fetal development are similar between human and non-human primate pregnancies, with the latter serving as a reliable, validated, highly-controlled, well-characterized translational model for the former.\n\nWe present a protocol for the preparation, immuno-labeling, and clarification of the non-human primate placenta optimized for confocal microscopy and subsequent quantification of the micro-anatomic structures.

pathology↗