Biology subjects

Perera, R.

Publications and source records attributed to Perera, R..

23 records · Page 2Linked to original sources

bioRxiv2021

Surface-aerosol stability and pathogenicity of diverse MERS-CoV strains from 2012 - 2018

Middle East Respiratory Syndrome coronavirus (MERS-CoV) is a coronavirus that infects both humans and dromedary camels and is responsible for an ongoing outbreak of severe respiratory illness in humans in the Middle East. While some mutations found in camel-derived MERS-CoV strains have been characterized, the majority of natural variation found across MERS-CoV isolates remains unstudied. Here we report on the environmental stability, replication kinetics and pathogenicity of several diverse isolates of MERS-CoV as well as SARS-CoV-2 to serve as a basis of comparison with other stability studies. While most of the MERS-CoV isolates exhibited similar stability and pathogenicity in our experiments, the camel derived isolate, C/KSA/13, exhibited reduced surface stability while another camel isolate, C/BF/15, had reduced pathogenicity in a small animal model. These results suggest that while betacoronaviruses may have similar environmental stability profiles, individual variation can influence this phenotype, underscoring the importance of continual, global viral surveillance.

microbiology↗

bioRxiv2020

Triple Combination Nitazoxanide, Ribavirin, and Hydroxychloroquine results in the multiplicative reduction of in vitro SARS-CoV-2 viral replication

BackgroundAn immediate unmet medical need exists to test and develop existing approved drugs against SARS-COV-2. Despite many efforts, very little progress has been made regarding finding low-cost oral medicines that can be made widely available worldwide to address the global pandemic. MethodsWe sought to examine if a triple combination of nitazoxanide (using its active metabolite tizoxanide), ribavirin, and hydroxychloroquine would lead to a multiplicative effects on viral replication of SARS-COV-2 resulting in a significant reduction of virus yield using VERO E6 cells as a model of viral replication. ResultsVirus yield measured in PFU/ml was ~ 2 logs lower with triple combination versus either drug alone, resulting in the prolongation of time to peak cytopathic effects (CPE). The time to produce 50% CPE increased from 2.8 days for viral controls versus 5.3 days for triple combination therapy. Finally, for each 1-log reduction in virus yield 24 hours post-infection, there was an additional 0.7-day delay in onset of CPE. ConclusionsA triple combination of tizoxanide, ribavirin, and hydroxychloroquine produced a reduction in SARS-COV-2 viral replication in Vero E6 cells, warranting exploration in additional cell lines as well as human clinical trials.

microbiology↗

bioRxiv2020

Development of SARS-CoV-2 Nucleocapsid Specific Monoclonal Antibodies

The global COVID-19 pandemic has caused massive disruptions in every society around the world. To help fight COVID-19, new molecular tools specifically targeting critical components of the causative agent of COVID-19, SARS-Coronavirus-2 (SARS-CoV-2), are desperately needed. The SARS-CoV-2 nucleocapsid protein is a major component of the viral replication processes, integral to viral particle assembly, and is a major diagnostic marker for infection and immune protection. Currently available antibody reagents targeting the nucleocapsid protein were primarily developed against the related SARS-CoV virus and are not specific to SARS-CoV-2 nucleocapsid protein. Therefore, in this work we developed and characterized a series of new mouse monoclonal antibodies against the SARS-CoV-2 nucleocapsid protein. The anti-nucleocapsid monoclonal antibodies were tested in ELISA, western blot, and immunofluorescence analyses. The variable regions from the heavy and light chains from five select clones were cloned and sequenced, and preliminary epitope mapping of the sequenced clones was performed. Overall, the new antibody reagents described here will be of significant value in the fight against COVID-19.

microbiology↗

bioRxiv2020

Lamin B2 follows lamin A/C- mediated nuclear mechanics and cancer cell invasion efficacy

Interstitial tumor cell invasion depends upon complex mechanochemical adaptation of both cell body and the rigid nucleus in response to extracellular tissue topologies. Nuclear mechanics during cell migration through confined environments is controlled by A-type lamins, however, the contribution of B-type lamins to the deformability of the nucleus remains unclear. Using systematic expression regulation of different lamin isoforms, we applied multi-parameter wet-lab and in silico analysis to test their impact on nuclear mechanics, shape regulation, and cancer cell migration. Modulation of lamin A/C and B2 but not B1 isoforms controlled nuclear deformation and viscoelasticity, whereby lamin B2 generally followed lamin A/C-mediated effects. Cell migration rates were altered by 5 to 9-fold in dense collagen environments and synthetic devices, with accelerated rates after lamin downregulation and reverse effects after lamin upregulation, with migration rates strongly depending on nuclear shape change. These findings implicate cooperation of lamin B2 with lamin A/C in regulating nuclear mechanics for shape adaptation and migration efficacy. SummaryNuclear deformability during cancer cell invasion and metastasis is critically regulated by lamin A. Here, researchers showed that lamin B2 also contributes to nuclear mechanics, implicating cooperating lamin networks regulating nuclear integrity, migration efficacy, and metastatic tumor progression.

cell biology↗

bioRxiv2019

Bubble Trouble: Conquering Microbubble Limitations in Contrast Enhanced Ultrasound Imaging by Nature-Inspired Ultrastable Echogenic Nanobubbles

Advancement of ultrasound molecular imaging applications requires not only a reduction in size of the ultrasound contrast agents (UCAs) but also a significant improvement in the in vivo stability of the shell-stabilized gas bubble. The transition from first generation to second generation UCAs was marked by an advancement in stability as air was replaced by a hydrophobic gas, such as perfluoropropane and sulfur hexafluoride. Further improvement can be realized by focusing on how well the UCAs shell can retain the encapsulated gas under extreme mechanical deformations. Here we report the next generation of UCAs for which we engineered the shell structure to impart much better stability under repeated prolonged oscillation due to ultrasound, and large changes in shear and turbulence as it circulates within the body. By adapting an architecture with two layers of contrasting elastic properties similar to bacterial cell envelopes, our ultrastable nanobubbles (NBs) withstand continuous in vitro exposure to ultrasound with minimal signal decay and have a significant delay on the onset of in vivo signal decay in kidney, liver, and tumor. Development of ultrastable NBs can potentially expand the role of ultrasound in molecular imaging, theranostics, and drug delivery.

bioengineering↗