Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Social history of viruses wikipedia , lookup
Ebola virus disease wikipedia , lookup
Bacteriophage wikipedia , lookup
Introduction to viruses wikipedia , lookup
Endogenous retrovirus wikipedia , lookup
Oncolytic virus wikipedia , lookup
Plant virus wikipedia , lookup
History of virology wikipedia , lookup
Papillomaviridae wikipedia , lookup
Virus quantification wikipedia , lookup
VIROLOGY - MCB 5505 VIRUS FAMILY: RHABDOVIRIDAE I. DISTINGUISHING CHARACTERISTICS A. LYSSA VIRUS (RABIES VIRUS) CAN CAUSE A RARE AND DEADLY ENCEPHALITIS B. ELONGATED, DISTINCTIVE “BULLET SHAPED” APPEARANCE C. VIRIONS CONTAIN AN RNA POLYMERASE ACTIVITY (L) THAT TRANSCRIBS AND REPLICATES GENOME RNA D. -STAND RNA IS NON-INFECTIOUS (NEITHER IS THE +STRAND) E. REPLICATION OCCURS IN THE CYTOPLASM OF HOST CELL WHICH ACTS AS A VIRUS “FACTORY” CREATING CYTOPLASMIC INCLUSION BODIES II. STRUCTURE A. SIZE: 70-180 nm IN DIAMETER B. ENVELOPE: YES 1. GLYCOPROTEINS: EXTERNAL (G) GLYCOPROTEIN 65kDa PROTEIN SPIKE 2. OTHER PROTEINS: NONE 3. MATRIX PROTEINS: INTERNAL (M) MATRIX PROTEIN 26kDa LINE ENVELOPE C. NUCLEOCAPSID 1. NUCLEIC ACID: HELICAL NUCLEOCAPSID a. TYPE: RNA BALTIMORE TYPE: V b. STRANDED: SS c. POLARITY: (-) d. # GENES: 5 2. GENETIC (PHYSICAL) MAP: VSV INTERGENIC SEQUENCE : AUACUUUUUUU GA UUGUC | | End Intergenic Start Katie Eggers 3. CAPSID- NUCLEOCAPSID a. SYMMETRY: ELONGATED, ROD “BULLET” SHAPE b. COMPOSITION: (1) PROTEINS: NUCLEOCAPSID (N) PROTEIN MAJOR 50kDa LARGE PROTEIN (L) 116-190kDa P PROTEIN 40kDa VIRUS FAMILY: RHABDOVIRIDAE III. CLASSIFICATION AND CHARACTERISTIC MEMBERS GENERA Lyssa virus PROPERTIES Infect vertebrates and some insects Vesiculovirus VSV infection of humans, mostly infects insects Ephemerovirus infects vertebrates IV. MEMBERS Rabies virus Makola virus Lagos Bat virus Vesicular Stomatitis Virus – VSV Cocal virus Alogoas virus Bovine ephemeral fever virus VIRAL MULTIPLICATION A. ABSORPTION: Attachment of viral glycoprotein (G) to a receptor on host cell surface, probably a phospholipid B. PENETRATION AND UNCOATING: Penetrates by a temperature and pH process, probably using endocytosis and fusion with the membrane of the vesicles meditated by the G protein. Uncoating happens in the cytoplasm where replication occurs. C. GENE EXPRESSION: The genome is transcribed into 5 mRNA’s, capped and polyadenylated. Glycoprotein (G) and Matrix protein (M) are both involved in the envelope. The viral core is found to be infectious, which shows that transcript activity is associated with the Largest protein (L), the Nucleocapsid protein (N) and the P protein. This makes the 3 internal proteins a functional replicase complex, although it is undefined as to how the RNA polymerase activity occurs. D. GENOME REPLICATION: The 5 mRNA’s are made by the sequential transcription of the ORF’s. Transcription starts at a single site, requiring the leader sequence. There is an intergenic sequence responsible for termination and reinitiation of transcription by the polymerase between each gene, producing separate transcripts. Replication requires the transcription of the (+) intermediate RNA strand, which serves as a template for progeny RNA and the mRNA that makes the viral proteins. The genome is replicated by the L and P polymerase complex, but requires additional unknown host factors. E. ASSEMBLY AND BUDDING: Virions are assembles around the tightly coiled core. The (-) strand is packaged. The M protein becomes attached to the host cell’s lipid bilayer, attracting the nucleocapsid proteins associated with the L and P protein molecules. The helical nucleocapsid buds through the lipid bilayer acquiring the M and G proteins. Small amounts of host cell plasma membrane proteins become a part of the viral envelope. Katie Eggers VIRUS FAMILY: RHABDOVIRIDAE V. CLINICAL CORRELATIONS A. The rabies virus was first shown infectious in 1808. Pasteur (in the (1880'S) succeeded in isolating an attenuated virus which he used to treat patients. Replication of the virus occurs locally in muscle and connective tissue with no symptoms, but eventually infects the peripheral nerves. It travels to the central nervous system where it causes a severe and fatal encephalitis. Rabies is transmitted by an animal bite that breaks the skin. The animal vectors can be foxes, bats, dogs, cats, etc. Passive immunization is required for those infected and must be done soon after transmission. There are no effective drug treatments. B. VSV causes an epidemic, self-limited disease in cattle. It can infect humans causing a mild febrile disease. Katie Eggers REFERENCES: http:// www.tulane.edu/~dmsander/www/335/Rhabdoviruses.html http://www.tulane.edu/~dmsander/BIG VIROLOGY/BVRNArhabdo.html http://life.anu.edu.au/viruses/ICTdB/620200000.htm Levy, J.A., et al. (1994). Virology , 3rd ed. Prentice Hall, New Jersey. Katie Eggers