Posted on Aug 09, 2018, 11 p.m.
Until 2015 viruses were believed to act independently to infect cells until demonstrated by researchers from the National Institute of Health that enteroviruses can travel collectively in packets. New evidence has been found that similar mechanisms can promote the spread of stomach viruses, which may help to inspire new therapies to prevent and treat illness such as norovirus and rotavirus.
In their previous study published in Cell the researchers discovered a trojan horse mode of viral transmission, finding after replicating in cells poliovirus particles assemble in groups packed in double layered lipid enriched vesicles that travel to the next host evading immune detection to the deposit the virus into the cell.
This study focused on 2 viruses mainly spread via accidental consumption of feces contaminated food or water : rotavirus and norovirus which both cause stomach illness including diarrhea and severe cases causing death. Norovirus is very contagious leading to outbreaks in crowded spaces such as nursing homes, daycares, and cruise ships.
Fecal samples from humans and animals were analyzed and the viruses were found live as cluster inside membrane cloaked packets, vesicles were significantly more infectious than free floating viruses within samples. Clusters allowed the virus to spread aggressively to increase severity of disease, and according to the researchers findings indicate vesicle cloaked viruses are virulent units of fecal-oral transmission and pointing out need for antivirals targeting vesicles and virus clusterings, as published in the journal Cell Host & Microbe.
Rotavirus vaccines are available, but currently there isn’t a way to protect against norovirus. A vaccine is being developed by Vaxart based on adenovirus type 5 vector-based platform designed to trigger immune actions in the GI tract, which has competed phase 1b studies with 90% of recipients in high dose groups displaying twofold increase in norovirus blocking antibodies 28 days after receiving doses.
It is not fully understood why virus vesicles render increased infectious powers, but there are a few theories such as vesicles may protect viruses from immune defense via making them invisible to host antibodies enabling vesicles to unload several viruses at once when at destinations. Viruses basically are going in with an army of sorts, a single genome entering a cell would be up against a lot until enough viral proteins are made and viral genome replicated to take over the whole cell, explains Nihal Altan-Bonnet, Ph.D of NIH.
Materials provided by: NIH/National Heart, Lung and Blood Institute.
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Marianita Santiana, Sourish Ghosh, Brian A. Ho, Vignesh Rajasekaran, Wen-Li Du, Yael Mutsafi, Dennise A. De Jésus-Diaz, Stanislav V. Sosnovtsev, Eric A. Levenson, Gabriel I. Parra, Peter M. Takvorian, Ann Cali, Christopher Bleck, Anastasia N. Vlasova, Linda J. Saif, John T. Patton, Patrizia Lopalco, Angela Corcelli, Kim Y. Green, Nihal Altan-Bonnet. Vesicle-Cloaked Virus Clusters Are Optimal Units for Inter-organismal Viral Transmission. Cell Host & Microbe, 2018; 24 (2): 208 DOI: 10.1016/j.chom.2018.07.006