August 1, 2015.
This material is based upon work supported by the National Science Foundation through the Robert Noyce Teacher Scholarship Program under Grant No. DUE 1340110. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
The STAR program is facilitated by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).
Bovine Coronavirus (BCoV) is an important analogue in understanding the effectiveness of zoonotic, single-stranded, positive sense RNA viruses. Many of the most recent viral outbreaks have been attributed to RNA viruses that have one, or more, animal reservoirs . BCoV is such a great candidate for studying these types of viruses because they are from the family Coronaviridae, which also contains the viruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The goal of this study was to observe changes in genetic makeup of the virus’ outer membrane Spike protein via recombination between two BCoV strains. The Nebraska strain and the Mebus strain were co-infected into a human cell line (HRT-18) in a 1 to 100 ratio and their rate of infection recorded. The Nebraska strain contains a 12 nt insert in its Spike protein which has been hypothesized to allow for trypsin-independent cell entry . Like SARS, BCoV has been found to require proteolytic cleavage by host trypsin in order for it to infect its host. To test the ability of the coronavirus strains to recombine and transfer this insert through template swapping, some cell lines were infected with the virus strains and incubated in media containing trypsin and trypsin-free media. RNA extraction of the virus present in the supernatant from the infected cells and subsequent RT-PCR and TaqMan PCR was used to determine the level of successfully infecting virus of each strain. The study concluded that, even at small levels, the presence of the Nebraska strain allowed recombination to occur and therefore boost the speed of infection and replication of the Mebus strain. Specific primers also indicated that the Mebus strain acquired the insert through template swapping. This results points out the importance of understanding the quasispecies of emerging viruses.
Biology | Virology
Lawrence Livermore National Laboratory (LLNL)