1. Host-Parasite Interactions Patrick Duffy 206 256 7311 pduffy@sbri.org

2. Outline of class Antigenic variation –Background –Primary literature Parasite modulation of immune response –T cell epitopes and immunomodulation –Parasite modulation of DC function –Primary literature Parasite co-opting the immune response Host resistance versus host immunity

3. Richie & Saul 2002 Malaria life cycle

4. ANTIGENIC VARIATION

5. SULFA Antigenic variants within strains Plasmodium knowlesi Brown & Brown 1965 Nuri strain in Rhesus VARIANT SPECIFIC IMMUNITY VARIANT TRANSCENDING IMMUNITY

6. Brown 1973 Nuri strain in Rhesus Antibody-induced variation NO VACCINEVACCINATED (variant A + IFA) Variant-specific immunity in monkeys P. knowlesi

7. Parasitemia Hommel 1985 Saimiri monkeys Strain A Inoculum (Indo-1) Strain B Inoculum (UgPA) Strain-specific immunity in monkeys P. falciparum

8. Parasitemia Yount & Coggeshall 1949 Joilet, IL prison studies QUININE Strain A inoculum Strain B inoculum Strain-specific immunity in humans P. vivax

10. Variant antigens on the IE surface P. falciparum Leech/Barnwell/Howard 1984 (P. knowlesi) MC extractSL extract IP with sera:  SL  MC 200 kD-- 1.Large MW 2.Tx100 insoluble/SDS soluble 3.Surface iodinatable (I125) 4.Strain-specific IP (similar to cytoadherence) 5. Trypsin-sensitive (similar to cytoadherence) Variant surface antigen: Serum antibodies from monkeys infected with Malayan Camp (MC) or Santa Lucia (SL) parasites

11. Exon-1 (Extracellular domain) Acidic Terminal Segment Exon-2 (Cytoplasmic domain) Semi-conserved head structure Tandem association TM Tandem association DBL1  CIDR1  DBL2  C2 CIDR2  ATS DBL4  DBL1  CIDR1  CIDR2  ATS DBL2  DBL5  DBL3  RosettingCD36ICAM-1PECAMCSA NTS Exon-1 Exon-2 CR1 HS Blood group A Heparin CD31 IgM CSA CSA/C IgG Cell 1995 Su & Wellems Smith & Miller Baruch & Howard Many years later… PfEMP1

12. CD36 Binding and Non-binding PfEMP1 Groups CD36 binding Non-CD36 binding Joe Smith ~60 copies per haploid genome Majority are subtelomeric

13. Switching in T. brucei

15. PRIMARY LITERATURE Bull et al., J Infect Dis 182:252

16. SICK RECOVERED ISOLATE SICK RECOVERED ISOLATE AGGLUTINATION SCORE01234 3 MONTH OLD CHILD 26 MONTH OLD CHILD Bull & Marsh 1999 Serum agglutination of field isolates: Evidence for variant specific immunity

17. FIELD ISOLATES SERUM SAMPLES Serum agglutination of field isolates: Rare Variants and Prevalent Variants Bull & Marsh 1999

21. IMMUNE MODULATION

22. HLA Class I molecules may be involved in liver stage immunity Hoffman, S. L and Doolan, D. L. ( 2000) Nature Medicine

23. HLA Class I antigen associated with resistance to severe malaria Hill et al., Nature, 1991

24. Expected at Parasite Rate of CSP variantObserved100%50%10% cp263658138*195* cp27405257*329*378* cp2815103048* cp29163389*134* cp26 & cp2912422* 6* cp27 & cp29499*53*11 cp26 & cp2771171*8216* cp26 & cp282772 *P<.05 Frequency of CSP variants in parasites collected from 795 Gambians with malaria. Reciprocal CTL antagonism in PBMC cultures by two naturally occurring P. falciparum CS protein variants. Gilbert et al., Science, 1998 CS protein and HLA B35: Evidence for Host-parasite Co-evolution?

25. Taylor et al., 2000

27. Urban et al. Figure 2

28. MF Good commentary Nature 1999

29. PRIMARY LITERATURE

30. Fig. 1

31. Fig. 2

32. Fig. 3

33. Fig. 4

34. Fig. 5

36. Fig. 6

37. CO-OPTING THE IMMUNE SYSTEM

38. S. mansoni expresses host-like molecules on its surface Trottein, JI, 1997

39. Immune masking Ig and associated complexes affinity-purified from S. mansoni with protein G McManus, 2001

40. Adsorption of human Ig on the surface of red cells infected with P. falciparum IgG IgM Flick, 2001

41. Schistosomes develop poorly in RAG -/- mice McKerrow 2001

42. S. mansoni development in mouse liver requires CD4+ T cells McKerrow 2001

43. IS RESISTANCE IMMUNITY? Resistance to malaria during childhood and adolescence

44. Parasitemia Pregnancy malaria Severe childhood malaria Prevalence Age (years) Epidemiology and Immunity 11020

45. 0 10 20 30 40 50 60 70 80 2-56-1011-1516-2526-40>40 Age group (years) migrants after 8 months exposure migrants after 20 months exposure Adults acquire resistance more rapidly than children Baird 1995

46. Age and susceptibility Weeks after treatment 0 20 40 60 80 100 02468101214 16 Age 12-14 Age 15-20 Age 21-35 P < 0.0001 n = 243 Volunteers infected (%) 0 1 2 3 4 5 6 Tanner Stage 12-14 15-20 21-35 Age group (yrs)

47. Mean Parasitemia Age (yrs) DHEA-S level: low medium high DHEA-S levels predict resistance to malaria

48. Culture of Plasmodium falciparum Effect of DHEAS in vitro 0 1 2 3 4 5 6 7 024487296120144 Serum+ DMSOSerum + DHEAS Time (hours) % Parasitemia

49. IS RESISTANCE IMMUNITY? Resistance to pregnancy malaria

51. Parity-related Susceptibility to Placental Malaria (1500 deliveries in Kisumu, Kenya) Rate (%) Mean parasite density (%IE) 0 20 10 30 0 6 2 8 4 Primigravid Secundigravid Multigravid

52. Parasites infecting pregnant mothers are different than other parasites Parasite adhesion to placenta ex vivo Placental parasitesParasites from adult males Fried, Duffy 1996 Parasites of Pregnancy Malaria

53. BSACSACD36 Placenta 2 110 2 Placenta 1 103 3 Male 10 59 Male 49 143 Parasite source Parasites bound* Ex vivo assay: Placental parasites ( ) bind to lining of placenta *per 20 hpf Villus

54. Birth weight (kg) Anti-adhesion Ab Level PrimiSecundiMulti -40 0 40 80 120 0 40 80 120 1.52.53.54.5 Antibodies and Pregnancy Outcomes 5/21 2/47 LBW Gravidity Antibodies against Parasites of Pregnancy Malaria

55. Take Home Lessons Antigenic variation– multigene families, mechanisms differ between parasites Parasites modulate the immune response Parasites co-opt the immune system Resistance to parasites may or may not be immune-mediated