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Rhabdoviruses and Filoviridae 4/10/13 Rhabdoviruses VSV-vesicullar stomatitis viruses Rabies viruses -RNA genome (means envelope) Bullet shaped Helical capsid Genome associated with 3 proteins N-nucleoprotein L-Large P- protein L+P=RNA polymerase Matrix present beneath envelope G-glycoprotein that facilitates attachment to nicotinic acetylcholine receptors at neuromuscular junctions Normal -RNA replication Genome released in cytoplasm Transcription into mRNA and + RNA Translation of mRNA RNA associated proteins bind -strand in cytoplasm G protein-translated within endocytic vesicle and goes to cell surface Matrix lines the inside of host cell Capsid forms and budding forms bullet envelope Zoonotic infection-from bite of animal (or other close association) Canine problem throughout the world-no vaccination of dogs In US skunks, coyotes, and raccoons are becoming bigger problem Last 12 fatalities in US associated with bats (no bites evident) Incubation period-can last from 2 weeks to several months Virus present at bite site, but has not spread to CNS Viruses infect neurons and move toward CNS via retrograde fast axonal transport Viral protein binds to dynein and allows movement along microtubules Once in CNS the virus spreads quickly The virus causes neuronal dysfunction due to changes in neurotransmission Acetylcholine, serotonin, and GABA affected Only slight indication of neuropathy Apoptosis and necrosis both at work Eventually leads to dementia and death Treatment-virus is 100% lethal if untreated in humans VaccinationActive and passive-slow progression of disease allows active immunization to be effective. Also receive purified Igs. Filoviridae Filamentous -RNA viruses Often cause hemorrhagic fevers Marburg 1st identified (50% mortality) Ebola best known 3 strains Zaire, Sudan and Reston Reston does not cause symptoms in humans but may be protective Zaire and Sudan have GP that causes endothelial cells to die and causes blood vessels to leak. The GP from Reston does not cause these changes. Ebola probably carried by bats as reservoir Chimps also infected and transmission may occur while "processing" chimps Burns out under normal conditions High lethality prevents spreading Most outbreaks linked to hospitals Using one needle to inject many patients Well known from movies and books Really weak science here
