R. Frank Cook Charles J. Issel Gluck Equine Research Center University of Kentucky What is a Lentivirus?
Family: Retroviridae
Subfamily: Orthoretrovirinae
Genus: Lentivirus Retrovirus Host DNA
Reverse Transcriptase
Single Double Strand Stranded RNA DNA
Viral Provirus Genome Retroviruses
AncientAncient 100100 -- 150150 xx 1010 6 yearsyears (Benit et al., 1999, Katzourakis et al., 2009)
EndogenousEndogenous (defective)(defective) RetrovirusesRetroviruses == 88 -- 10%10% ofof humanhuman genomegenome LT GAG POL ENV LT R R
Structural Core Replicative Envelope Surface Proteins Enzymes Glycoproteins p15, p26, p11, p9 Host Defenses
ImmuneImmune Response:Response: InnateInnate AdaptiveAdaptive RetroviralRetroviral RestrictionRestriction Factors:Factors: ••ApolipoproteinApolipoprotein ββ EditingEditing ComplexComplex 33 (APO(APO ββEC3)EC3) ••TripartiteTripartite MotifMotif --ContainingContaining ProteinProtein 55 αααααα (TRIM5(TRIM5 αααααα)) ••TetherinTetherin APO βEC3 (Cytosine Deaminase)
vRNA TRIM 5 ααα Tetherin Lentiviral Characteristics
Genetically, Morphologically Distinct Infect Non-Dividing Cells Hostile environment Low dNTP (SAMHD1) High dUTP
Evolved Additional ORFs to GAG, POL, ENV Complex Retroviruses
Additional / Ancillary Lentiviral Genes
TatTat TransactivatorTransactivator forfor VpuVpu CD4CD4 ↓↓↓↓↓↓ replicationreplication TetherinTetherin ↓↓↓↓↓↓ RevRev ExportExport ofof viralviral RNARNA OrfAOrfA CD134CD134 ↓↓↓↓↓↓ fromfrom nucleusnucleus nefnef CD4CD4 –– dUTPasedUTPase dUTPdUTP →→ dUMPdUMP signalingsignaling S2S2 BindsBinds cellularcellular ––intracellularintracellular proteinsproteins traffickingtrafficking InflammatoryInflammatory ––cellcell cytokinecytokine ↑↑↑↑↑↑ migrationmigration ––apoptoticapoptotic VifVif APOAPO ββEC3EC3 pathwayspathways degradationdegradation VpocVpoc SAMHD1SAMHD1 degradationdegradation Timeline of Lentiviral Evolution MolecularMolecular ClockClock EstimateEstimate EntireEntire GenusGenus == << 11 millionmillion yearsyears IndividualIndividual LentivirusesLentiviruses == 100100 ’’ss toto 10001000 ’’ss yearsyears HumanHuman HIVHIV --1M1M 19081908 –– 19331933 GorillaGorilla SIVgovSIVgov 18181818 –– 19061906 ChimpanzeeChimpanzee SIVcp2SIVcp2 12661266 –– 16851685
Wertheim et al., 2009 Worobey et al., Lentivirus Distribution RetrovirusesRetroviruses AllAll VertebratesVertebrates
EIAVEIAV SRLVSRLV
BIVBIV FIVFIV
HIVHIV SIVSIV Perissodactyla
66 -- 88 xx 1010 6 yryr
88 -- 99 xx 1010 6 yryr
33 xx 1010 6 yryr EIAEIA VV Revised Timeline of Lentiviral Evolution
DefectiveDefective EndogenouEndogenou LentiviruseLentiviruse ss ss
RELIKRELIK PSIVPSIV ELVmpfELVmpf 1212 xx 1010 6 yryr 4.24.2 xx 1010 6 1212 xx 1010 6 yryr yryr Endogenous Lentiviruses
Older Expand Host Range Lagomorph Prosimian Carnivore Extinction Lentiviral Genome Organization Lentiviral Phylogeny ?
– dUTP +NEF,Vpu/Vpx +OrFa
+Vif
+dUTP +S2 EIAV Infects ALL Equidae Persistent Infection – NOT eliminated by host responses Simplest genome organization of any extant Lentivirus dUTP TAT REV S2 Only extant Lentivirus - VIF EIAV and Retroviral Restriction Factors
APOAPO ββEC3EC3 –– HorseHorse moremore genesgenes thanthan anyany otherother nonnon --primateprimate speciesspecies –– NotNot blockedblocked byby EIAVEIAV –– PackagedPackaged inin virionsvirions –– ?? TRIM5TRIM5 αααααα –– EIAVEIAV p26p26 resistant?resistant? –– ExpressionExpression inin horses?horses? ((∆∆∆∆∆∆TRIM5TRIM5 αααααα inin Canidae)Canidae) TetherinTetherin –– EIAVEIAV EnvEnv resistant?resistant? IsIs EIAVEIAV aa primitiveprimitive lentivirus?lentivirus? Host Cell Types EIAVEIAV
T Lymphocyte CD4+
Dendritic Monocyte Macrophage Cell Infects No Progeny Productive Productive (Trojan Horse?) Infection Infection EIA Clinical Signs Pathogenesis of Acute EIA
plateletplatelet THROMBOCYTOPTHROMBOCYTOP agonistsagonists ENIAENIA thrombinthrombin megakaryocytemegakaryocyte ANEMIANEMI plasminplasmin colonycolony AA serotoninserotonin ggrowthrowth factorfactor TNF αα TNF PGEPGE ILIL --11 erythropoiesiserythropoiesis 22 FEVE αα,,ββ FEVE ILIL --66 RR blood/tissublood/tissu TGFTGF ββ ee thresholdthreshold EIA Clinical Signs Highly variable Sub-clinical – Death Individual Equid Species Platelets x 1000/µl x Platelets Platelets x 1000/µl x Platelets Temp C Temp Temp C Temp
Days Post Infection Days Post Infection Host Management of Lentiviral Infections ? Natural:Natural: ?SIVSIV // AfricanAfrican NonNon --HumanHuman PrimatesPrimates SubclinicalSubclinical ViralViral ReplicationReplication –– HighHigh ImmuneImmune ControlControl –– IneffectiveIneffective LimitLimit Pathogenesis,Pathogenesis, CD4CD4 DepletionDepletion NEF – CD3 -TCR ↓↓↓↓↓↓ NonNonNEF-- Natural:–Natural:CD3 -TCR HIVHIV // Humans,Humans, SIVSIV // AsianAsian MacaquesMacaques AIDSAIDS ViralViral ReplicationReplication –– HighHigh ImmuneImmune ControlControl –– Limited,Limited, TransientTransient (Exception(Exception –– eliteelite controllers?)controllers?) LackLack MechanismsMechanisms toto LimitLimit PathogenesisPathogenesis EIAV / Horse NaturalNatural ImmuneImmune Suppression:Suppression: ViralViral LoadLoad ↑↑↑↑↑↑ DiseaseDisease Transient Long Term Strain Cross - Specific Reactive Loads Loads Temp / Viral Viral / Temp Temp / Viral Viral / Temp
Acut Chroni Inapparent e c Antigenic Variants (SU -ENV) Immunological Control of EIAV No simple correlate of protection Differences between individual horses Model for Elite Control of HIV in humans? Other mechanisms? EIAV SU : A Critical Role
Attachment/Entry Neutralizing Epitopes SU PND Amino Acid Sequence
NSSDSSNPVRVEDVM
I
II S
II G S I I ************** V VT GP S G YET Based on EIAV UK3 infectious molecular clone (Cook et.al. Virology 313: 588-603, 2003)
LTR SU TM LTR S2 RNA copies/mlX plasma EIAV S2 10 2 – 10 4 8 EIAV UK3 >10 Immunize Horses EIAV 2, challenge >6 months
75-100% Protection from INFECTION from HOMOLOGOUS challenge Pony 564 EIAV PV = EIAV UK3 SU = EV0
Febrile episode IV @260dpi (6% divergence = SU = EV6)
Inapparent 1219dpi (13% divergence SU = EV13)
EV 0
EV6
EV13 24 S2 Vaccinated Ponies
Challenge 8 EV0 8 EV6 8 EV13 (Homologous Env) (6% Difference in Env) (13% Difference in Env) Protection Protection Protection Disease Infection Disease Infection Disease Infection 87.5% 75% 62.5% 37.5% 37.5% 0% 100 75 50 25 Infection 0 Protection from Protection 0 6 13 Env Divergence Variation in EIAV SU
Establishment of persistent infection
Critical role in vaccine efficacy (related strains)
Limited by structure and function? Variation in EIAV SU
Dong J -B, Zhu W, Cook RF, Goto Y, Horii Y, Haga T (2012) Lesson Learned
Lentiviruses: complex >12x10 6 YR Few mammalian hosts – Extinct
EIAV : Least complex genome Successful/Persistent Integration MØ host cell Neutralization Ab resistant Antigenic variation Lesson Learned
Disease = High Viral Loads
Inapparent Carrier = Low Viral Loads Immunological Control Horse = Model for Elite HIV Control?
Vaccine Efficacy : Variation in SU Lessons to be Learned
? Extent of EIAV Diversity Molecular Diagnostics Vaccines
? EIAV Persistence Mechanisms
? Evasion of Host Restriction factors NO VIF/VPU Lessons to be Learned
Immunological Control Mechanisms NO Simple correlations Other mechanisms
? Differences between Horses in Disease and Control
? Differences between Equid species MIYAZAKI
0 0 1 UK IRE Dr. Takeshi Haga, University of Tokyo Drs. Quinlivan and Cullinane, Irish Equine Center
Sheila J Cook (MSc) and Diane Furry, Gluck Equine Research Center.