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ARENAVIRIDAE

ARENAVIRIDAE. Avner Yemin MCB5503 Presentation. ARENAVIRIDAE TAXONOMY. Arenavirus Phylogeny. Family: Arenaviridae Genus: Arenavirus Two Subgroups: determined from Amino Acid serogrouping and geographic distribution 1) Old World Arenavirus, aka LCMV-LASV Complex

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ARENAVIRIDAE

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  1. ARENAVIRIDAE Avner Yemin MCB5503 Presentation

  2. ARENAVIRIDAE TAXONOMY Arenavirus Phylogeny • Family: Arenaviridae • Genus: Arenavirus • Two Subgroups:determined from Amino Acid serogrouping and geographic distribution • 1) Old World Arenavirus, aka LCMV-LASV Complex • 2) New World Arenavirus, aka Tacaribe Complex

  3. Virion Morphology • Spherical Shape, Slightly Pleomorphic • Lipid Membrane Envelope • Diameter 50-300nm (average 110-130) • Two Filamentous Nucleocapsids per envelope, each with “string of beads” appearance and Helical Symmetry • Sandy appearance of riboprotien structure (Latin derivation “arena”=sand)

  4. Diagrammatic Representation of Morphology

  5. ArenavirusGenome • Multipartite = multiple copies of genome per virion • Ambisense Genome • Most of genome is (-) sense except for part of 5’ ends on L and S • Each Virion has two segments of linear ssRNA • 1) L (large) 7.0-7.3kb • 2) S (small) 3.4 kb • Genomic Distribution: • S (smaller) RNA is more abundant than the L (larger) RNA • S (Smaller) RNA codes for structural components • Glycoprotein precursor (GPCGP1+GP2) and Coat Protein (N) • L (Larger) RNA codes for non-structural components • Zinc Binding Protein (Z) and RNA Polymerase (L) • Circular nucleotides are created via complementary sequences at 5’ and 3’ ends bonding using Hydrogen Bonds

  6. Diagrammatic Representation of Genomic Structure and Genomic Replication Strategy

  7. Arenavirus Replication Strategy • 1) Entry into cell via endosomal route (receptor unknown) • 2) Viral Uncoating in cytoplasm releasing genome • 3) Transcription of (-) sense 3’ half of S RNANuclear Coat protein (N) mRNA • 4) Transcription of (-) sense (3’) half of L RNARNA Polymerase (L) mRNA • Transcription termination (hairpin) signal in center of S RNA • Capping via cellular RNA “cap-snatching” • Translation of N and L proteins before genome replication • Transcription of glycoprotein (GPCGP1, GP2) and Zinc-binding protein (Z) mRNA’s • Budding of virion from plasma membrane with no cell death

  8. Diagrammatic Representation of Arenavirus Replicative Cycle

  9. Arenavirus Overview(HINT HINT!!!) • Naked RNA is non-infectious • Rodent transmitted viruses (zoonotic) • Exception: Tacaribe virus isolated from BATS (aren’t rodents) • Two Subgroups a) LCMV/LASV and b) Tacaribe • Name derivation due to riboprotein structure (sandy) • Multipartite with two segments of the genome 1) S and 2) L

  10. ARENAVIRUS FAMILY HISTORY • Lymphatic Choriomeningitis virus (LCMV) first Arenavirus discovered in 1933 during study of St. Louis Encephalitis • 1960’s – Birth of Arenaviridae after discovery of other similar viruses • Tacaribe virus (1956) • Junin virus (1958) – First Hemorrhagic Arenavirus • Machupo virus (1963) • Lassa virus in Africa (1969) • Sabia and Guanarito have recently been added • A new Arenavirus is discovered every 1 to 3 years on average • Now separate Arenavirus into two groups based on geographic distribution and antigenic relationship 1)New World (Tacaribe) and 2)Old World (LCMV/LASV complex)

  11. ARENAVIRUS INFECTION • Human infections caused by: • Exposure to rodent excrement • Inhale urine polluted dust • Contaminated food • Wound exposure • Person-to-Person spread • Nosocomial (hospital setting) • Contact infected blood • Contact contaminated medical devices

  12. BEWARE OF THOSE PESKY RODENTS • Fatal Illnesses Associated With a New World Arenavirus --- California, 1999--2000The California Department of Health Services (CDHS) and the University of Texas Medical Branch (UTMB) recently identified evidence of infection with an arenavirus in three patients hospitalized with similar fatal illnesses. This report summarizes the investigation of these cases. Patients had onset of illness during June 1999--May 2000. They were aged 14, 30, and 52 years; all were female. Two resided in southern California and the third in the San Francisco Bay area. The patients did not have any activities in common, and none had a history of travel outside California during the 4 weeks preceding their illness. Illnesses were associated with nonspecific febrile symptoms including fever, headache, and myalgias. Within the first week of hospitalization, lymphopenia (25--700 per mm3) was observed in all three patients, and thrombocytopenia (30,000--40,000 per mm3) was seen in two. All three patients had acute respiratory distress syndrome and two developed liver failure and hemorrhagic manifestations. All patients died 1--8 weeks after illness onset.Arenavirus-specific RNA was detected in one or more materials from each patient using a nested RT-PCR assay. In addition, infectious arenavirus was recovered from materials from the 14-year-old patient by cultivation of the virus in monolayer cultures of Vero E6 cells; virus isolation attempts on materials from the 30-year-old patient are under way. The nucleotide sequence of the PCR products amplified from the patients essentially were identical and shared 87% identity with the Whitewater Arroyo (WWA) virus prototype strain (an arenavirus recovered from a Neotoma albigula [white-throated woodrat]) from New Mexico in the early 1990s). Serologic assays (indirect fluorescent antibody assay and IgG enzyme immunoassay) for arenavirus antibody were negative for all three patients. Family members of the three patients were interviewed about activities and potential exposure sites during the month before illness onset. One patient reportedly cleaned rodent droppings in her home during the 2 weeks before illness onset; no history of rodent contact was solicited for the other two patients.

  13. Human Arenavirus Infections

  14. Geographic Distribution of Arenaviridae

  15. LASSA FEVER OVERVIEW AND EPIDEMIOLOGY • An acute viral illness that occurs in West Africa • Host is the multimammate rat • (note hairless tail) • Most Common Complication is deafness • 1/3 of cases • Significant Cause of Morbidity and Mortality on Endemic West Africa • No symptoms in 80% of people infected • Remaining 20% have multi-system disease • 100,000-300,000 cases/yr with 5,000 deaths • Occasional Epidemics occur • Case-fatality rate can reach 50%

  16. Mortality Rate of Lasa Fever • 15%-20% of patients hospitalized for it end up dead • However, overall mortality rate is about 1% • Lassa is particularly deadly for women in their third trimester of pregnancy and fetuses • 95% mortality rate Lassa virus electron micrograph. Image courtesy, C.S. Goldsmith and M. Bowen (CDC).

  17. LASA FEVER COURSE OF DIESEASE Fever Headache Arthralgias/Myalgias Retro-sternal Pain Weakness Dizziness Sore throat/Pharyngitis Cough Vomiting Abdominal Pain/Tenderness Diarrhea Hemorrhage Chills Deafness Lymphadenopgathy Mucosal Bleeding Confusion Swollen Neck or Face 0 10 20 30 40 50 60 70 80 90

  18. LASA FEVER DIAGNOSIS • Most often using Enzyme-Linked Immunosorbent Serological Assays (ELISA) • Detects IgM and IgG antibodies • Detects Lassa antigen • Can also be detected via Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) • Primarily used for research purposes

  19. LASA FEVER TREATMENT • Ribavirin has been used successfully in Lassa Fever patients • Ribavirin acts as a Guanosine analogue • The earlier treatment is applied the more effective the drugs are RIBAVIRIN

  20. What the Future Holds • Lassa viruses comprise a group of genetically highly diverse strains, which has implications for vaccine development. • The new method for full-length S RNA amplification may facilitate identification and molecular analysis of new arenaviruses or arenavirus strains.

  21. SOURCES • http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/arena.htm • http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/lassaf.htm • http://www.cdc.gov/ncidod/eid/vol6no5/gunther.htm • The Universal Virus Database of the International Committee on Taxonomy of Viruses ICTVdB http://www.ncbi.nlm.nih.gov/ICTVdb/index.htm • MedicineNet.com http://www.medterms.com/script/main/art.asp?articlekey=26655

  22. SOURCES CONTINUED • Descriptions of Plant Viruses http://www.dpvweb.net/notes/showfamily.php?family=Arenaviridae • The Big Picture Book of Viruses http://www.virology.net/Big_Virology/genusarena#genusarena • WrongDiagnosis.com http://www.wrongdiagnosis.com/l/lassa_fever/intro.htm • Species - http://212.187.155.84/pass_06june/Subdirectories_for_Search/SpeciesKingdoms/virus/arenaviridae/TopOfPage

  23. ANY QUESTIONS ???? ??

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