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The Ebola,Marburg,and Lassa viruses are dangerous pathogens that are capable of outbreak from their animal reservoirs,which can lead to devastations of local human populations.Despite their lethality,these pathogens currently have very limited treatment and vaccination options available to those infected.Ebola and Marburg viruses are Filoviruses,enveloped negative single-stranded RNA that replicate in the cytosol.Filoviruses that form strand like structures under a microscope,primarily infecting animal hosts but capable of transmitting to human hosts through transmission through bodily fluids such as blood.Once a human infection has been established,outbreak can occur,especially in countries with poor water,sewage,and burial hygiene such as Guinea,Sierra Leone,Liberia,and others,leading to devastation of local populations.In the course of the Ebola outbreak of 2015,there were 27,000 eases resulting in 11,000 deaths as of August 11th 2015,highlighting the need for treatment options for filoviruses to slow this kind of outbreak.Lassa Virus is an Arena virus that infects primarily rodents and sometimes humans.They are round,grainy looking enveloped viruses with a segmented,ambi-sense or negative sense RNA genome that reproduce in the cytosol.Estimations that Lassa Virus infects between 300,000 to 500,000 people per year,resulting in around 5,000 deaths,clearly demonstrates the need for effective anti-viral treatments.However,researchers that choose to develop these treatments face unique challenges because the live forms of these viruses are too dangerous to work with in a standard laboratory setting,requiring biosafety level 4 conditions.This limits the speed at which effective treatments can be tested because of the high operating cost associated with the equipment and protocol needed for biosafety level 4 laboratories and the limited number of maximum biosafety facilities.Viral pseudotyping is a technique that circumvents this limitation by creating non-pathogenic vectors that still behave like viruses in many ways,but critically cannot replicate.Viral pseudotyping involves enveloping a core viral protein with a foreign viral coat.The foreign viral envelope still contains all of its protein machinery required for membrane fusion,allowing anti-viral candidates to be tested that inhibit fusion without risk of using live viruses that can reproduce,infect,and potentially outbreak.This technique allows labs such as this one and many others to test anti-viral candidates that effect membrane fusion in a standard lab environment.The primary limitation of this procedure is it relies on the assumption that the membrane fusion of the pseudovirus accurately mimics that of its live,infectious counterpart.While it is possible that this might not be the case viral pseudotyping has nevertheless proven itself to be a useful and productive model of real live viruses.Procedures taken to prepare pseudoviruses over a two month period,beginning with a set of experiments designed to identify the errors in conducting the procedure,then testing this hypotheses while detailing how optimization in PEI concentration might be able to maximize pseudovirus yield.