Stochastic model of BKPy Virus replication and assembly

Abstract BK Polyomavirus (BKPyV), belongs to the same family as SV40 and JC Virus and has recently been associated with both Sjögrens Syndrome and HIV associated Salivary Gland Disease. BKPyV was previously only known for causing the rejection of kidney transplants. As such, BKPyV infection of salivary gland cells implicates oral transmission of the virus. BKPyV replicates slowly in salivary gland cells, producing infectious virus after 72-96 hours. However, it remains unclear how this virus infects or replicates within salivary gland cells, blocking the development of therapeutic strategies to inhibit the virus. Thus, an intracellular, computational model using agent-based modeling was developed to model BKPyV replication within a salivary gland cell. In addition to viral proteins, we modeled host cell machinery that aids transcription, translation and replication of BKPyV. The model has separate cytosolic and nuclear compartments, and represents all large molecules such as proteins, RNAs, and DNA as individual computer “agents” that move and interact within the simulated salivary gland cell environment. An application of the Boids algorithm was implemented to simulate molecular binding and formation of BKPyV virions and BKPyV virus-like particles (VLPs). This approach enables the direct study of spatially complex processes such as BKPyV virus self-assembly, transcription, and translation. This model reinforces experimental results implicating the processes that result in the slow accumulation of viral proteins. It revealed that the slow BKPyV replication rate in salivary gland cells might be explained by capsid subunit accumulation rates. BKPyV particles may only form after large concentrations of capsid subunits have accumulated. In addition, salivary gland specific transcription factors may enable early region transcription of BKPyV.