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Human Parvoviruses. Kevin E Brown Immunisation and Diagnosis Unit Virus Reference Department Centre for Infections. Parvoviruses. Small 22-24 nm non-enveloped 4 - 5.5 kb ss DNA genome with ITRs at 5’ and 3’ ends Encode no polymerase
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Human Parvoviruses Kevin E Brown Immunisation and Diagnosis Unit Virus Reference Department Centre for Infections
Parvoviruses Small 22-24 nm non-enveloped 4 - 5.5 kb ss DNA genome with ITRs at 5’ and 3’ ends Encode no polymerase Dependant on cellular/other viral proteins for DNA replication 2 large ORF NS (or Rep) proteins VP (or Cap) proteins Classification Two subfamilies – host range Densovirinae – insects Parvovirinae – vertebrates Autonomous/dependant replication + or – strand packaging Identical or different 5’ and 3’ ITRs 1, 2 or 3 promoters Sequence pyhlogeny
Parvovirus B19 • First identified in 1974 (CPHL, London) • ~ 22 nm icosahedral virion • Linear single stranded DNA • ~ 5600 nucleotides • Long (383nt) terminal hairpin seq • Complex transcription map • Single promoter (p6) • 1 non-spliced non-structural protein • 2 capsid proteins (VP1 & VP2) -alt splicing • Small proteins of unknown function • VP2 self assembles to form VLP • Erythrotropic • Does not grow in standard tissue culture • Replicates in erythroid progenitors • Rare cell lines (UT7/Epo; KU812Ep6)
A6 V9 Phylogenetic tree of VP1u region Servant et al. J. Virol 2002
Prevalence of variant B19 in different groups * Only detected in those born before 1973
1st identified in a IVDU • Fever, arthralgia, meningism • Acute sample only • Lost to follow up • Closest sequence • Putative Erythroviruses • Chipmunk
Parv4 DNA • Typical parvovirus features • Incomplete hairpin sequence • Gap between NS and capsid • VP1 ~ 100 kDa • No 11 kDa or 7.5kDa ORFs
Prevalence of PARV4 virus using nested PCR Blood donors from Los Angeles area summer 2005 300 pools of 16 29 positives (9.6% or 0.6% if divided by 16). 200 single donations 4 positives (2%) Subjects with symptoms of acute viral infection or highly exposed (MSM, IDU) 16/195 subjects positive (85) 1 PARV5, PARV4 Increasing prevalence in symptomatic/exposed subjects may reflect pathogenic viral infection OR higher exposure to blood borne viruses (e.g. like GBV-C)
Genetic variation among PARV4 10 20 30 40 50 60 70 80 90 100 ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+ gttgatggccctgtggttagCACCCAGCATCAAGAAGCTTTGCAGACAAGAATAACCATGTTTCAGTTTCAGAGAATGGTTCCGGATGGCTTAGCTCCAC PARV4-Cutter pool-1991 ........y..................................G........................................................ Poolx16 24/29 ........y........................................................................................... Poolx16 2/29 ........y..................................R........................................................ Poolx16 1/29 ........y........................T.........G........................................................ Poolx16 1/29 ........y..................................G................................................R....... Poolx16 1/29 ........y..................................G........................................................ Neat 3/4 ........y..................................G.....................................T.................. Neat 1/4 ........y..................................G........................................................ Option 7/16 ........y........................................................................................... Option 3/16 ........y........................................................................................... Option 1/16 ........y..............................................T............................................ Option 1/16 ........y................R.................G........................................................ Option 1/16 ........y..................................G...R.................................................... Option 1/16 ........y.............................C....G........................................................ Option 1/16 ........y..............T........G......C..................................G........C...........C..T. Option 1/16 --......T..............T........G......C..................................G........C...........C..T. PARV5-Cutter-1991 110 120 130 140 150 160 ---------+---------+---------+---------+---------+---------+- TTCCTGAAGAGGAAGTGAGAAGCTTTTTTAAGCTAGgtgaacaggaactgaatatgaaagg PARV4-Cutter-1991 ............................................................. Poolx16 24/29 ............................................................. Poolx16 2/29 ............................................................. Poolx16 1/29 ............................................................. Poolx16 1/29 ............................................................. Poolx16 1/29 ............................................................. Neat 3/4 ............................................................. Neat 1/4 ............................................................. Option 7/15 ............................................................. Option 3/15 ...............................A............................. Option 1/15 ............................................................. Option 1/15 ............................................................. Option 1/15 ............................................................. Option 1/15 ............................................................. Option 1/15 .C....................T...........T.......................... Option 1/15 .C....................T...........T.......................... PARV5-Cutter-1991
Parv4 DNA VP2 expression • Bacteria • 60 kDa • Baculovirus • VLP • No HA • ELISA developed • Indirect format
Pooled NPA secretions • 48 samples • 38/48 pediatric patients • 378 NPA samples • Culture negative • 7/266 pediatric patients • 0/112 adult patients • 540 samples hospitalized peds • 3.1% pos • Increased in winter months • Closest sequence • Bovine parvovirus • CPV type 1 (MVC)
Human parvoviruses • Parvovirus B19 (B19V) – type member of Erythroviruses • 3 different genotypes now recognized • No evidence for different serotypes • Highly erythrotropic • Detection of DNA in blood and tissues for years following acute infection • No evidence of reactivation/integration • Parv4/5 is a new member of the Parvovidae • Sequences are uncommon in blood and blood products • No culture method available • VLP can be expressed • Do not resemble B19V • Do not HA • Parv4 Ab common in children/adults • Human bocavirus in respiratory secretions of children < 5 • Prevalence in other tissues/age groups • VLP can be expressed • Adeno-associated viruses – AAV2, 3, 5 are human viruses
Acknowledgements • Virus Discovery Group • Jun Lu • Ian Mills • Tri Nguyen • Susan Wong • Ning Zhi • Hematology Branch • Neal Young • Sachiko Kajigaya • Outside collaborations • Mavis Agbanje-McKenna • Sally Baylis • Eric Delwart • Erik Heegaard • Mei-Ying Yu • Health Protection Agency • Hazel Appleton