Pathogens are impacted on many levels by host responses

1. Pathogens are impacted on many levels by host responses -communication between host and pathogen in compatible response results in development -pathogen detection of host immune response antigen masking active suppression of defenses alternative development survival stages sporulation These are both infective agents for dispersal!

2. Pathogens must defend themselves against numerous factors

3. Rhizosphere bacteria secrete antimicrobials

7. The malaria pathogen alters its antigenic profile during development and infection

8. The available evidence suggests that nematodes both actively suppress defense responses and mask their surface profiles to avoid host detection! How? -secretion of enzymes -binding of host proteins -molting

9. The nematode cuticle offers an antigenic profile that is stage- specific and changes with each molt

10. Life cycle

11. Diapause Hatch Host Location Reproduction Penetration and Migration Feeding Site Establishment

12. ENVIRONMENTAL FACTORS CROWDING OF LARVAE TEMPERATURE ? INCUBATION OF GALLS NUTRITION ? RESISTANT VARIETIES ? OTHERS ? MH-30 Adult female Female intersex Second stage (late) Second stage (early) Adult male (sex reversed) Second stage (middle) Second stage (undif. larva) Adult male Third to fourth stage Second stage

13. Life cycle

14. Action Environmental Cues Sensory Processing DAF pathway INTER- NEURONS DAUER AMPHIDS SURFACE SEX

15. Infective second-stage larva of RKN arrested in development

16. Dauer larvae of the pine wood nematode

17. Dauer larvae characteristics • Non-developing • Non-feeding • Long-lived • Altered metabolism: • Resistance to SDS • Glyoxylate pathway • No high-energy phosphate • Lipid metabolism

18. C. elegans dauer pathway PREDAUER DAUER L2d EGG L1 L4 ADULT L2 L3

19. Pheromone Cue (DAF-22, Biosynthesis of pheromone:unknown receptor) Tgf- Signal Cyclic GMP Signal 3-Phosphoinositide Signal (DAF-7, Ligand: DAF-1, DAF-4, Receptor) (DAF-11, Guanylyl Cyclase) (AGE-1, Pl-3 Kinase) Steroid Or Retinoid Signal? (Unknown hormone: DAF-12, Nuclear receptor) Dauer Morphogenesis Continuous Development

20. ENVIRONMENTAL CUES SENSORY PROCESSING MORPHOGENESIS def-3 def-5 def-12 def-18 def-20 def--6 def-22 def-10 def-18 def-17 def-8 def--15 PHEROMONE def-1 def-4 def-14 def-7 def-11 def--9 Dauer larva other def--2

21. Enzyme found in C. elegans M. hapla Both species

24. Some bacteria sporulate in response to stress and environmental perturbation Courtesy: Tom Hewlett

25. The life-cycle of Pasteuria penetrans in excised root-knot nematodes: a re-evaluation Sporogenesis Attachment & Germination Rhizoid Formation & Exponential Growth

26. Sporulation The vulnerable vegetative cell partitions. A tough layer of protein and polysaccharide is laid down encapsulating the chromosome. The cell lyses and the protective spore is formed. Cell Lysis • Nutrient Starvation • Temperature or pH extremes • Cell crowding • Antibiotic exposure

27. Sporulation and competance genes occur in clusters 2537600 2517600 2519200 2531200 spoIIIAB spoIIIAF spo0A spoIIIAD spoIVB spoIIIAE spoIIIAA yghV efp spoIIIAH spoIIIAG spoIIIAC 2443200 2636800 2640000 2445600 sigF dacF comEC comEB comEA spoIIAB AA

28. Comparison of endospore formation in Bacillus thuringiensis and Pasteuria penetrans From Chen et al., (1997) Phytopathology 87, 273-283

29. Pasteuria penetrans (Sayre & Starr 1985) Bacillus anthracis (Driks 2002)

30. Occurrence of endospore coat proteins Bs Ba Pp Genes ____________________________________ + - - CotC; CotM; CotR; CotSA; CotT; CotV CotW; CotX; CotY; CotZ (38%) + + - SpoVM; SpoVID; CotB CotE; CotF; CotH; CotJC; CotS; YaaH; YabG (38%) + - + CotA; CotD; CotG (12%) + + + Spo1VA; SafA; CotJA (12%) _____________________________________ Positive hits using Artemis (June 2004) Driks (2002), Trends Microbiol. 10:251

31. 60.8 47.3 NA Filament length (nm) 48.7 28.4 29.8 24.8 25.1 13.9 BclA collagen-like repeats and their relationship to filament length in B. anthracis after Sylvestre et al. (2003), J. Bact., 185

32. B. anthracis BclA vs. P. penetrans 79% identity B. anthracis BclA vs. P. penetrans 78% identity B. cereus Protein H vs. P. penetrans 64% identity Pasteuria Collagen-like G-X-Y repeats

33. How is regulation of sporulation controlled?

34. KinB Cell Membrane KinA RapB Spo0F PI RapA Spo0B Spo0A Spo0A sporulation DNA binding domain DNA binding domain abrB Inactive Active Diagram of proteins involved in the phosphorelay required for initiating the sporulation signal transduction pathway in B. subtilis (from Feher et al., 1998). The open arrows represent environmental signals which initiate the transfer of the phosphoryl group via the phosphorelay.

35. Multi-component phosphorelay P P P P H H ATP D D ATP Spo0F KinA Spo0A H H P Signaling pathway of sporulation two-component phosphorelay In many bacteria, the onset of sporulation is assured by the activation of this very signal specific signal transduction pathway

36. β1 α1 α2 α3 β2 β3 1nat .. . . . . . . . SPOF_BACSU MMNEK..ILIVDDQYGIRILLNEVFNKEGYQTFQAANGLQALDIVTKERPDLVLLDMKIPGMDGIEILKR 1 10 20 30 40 50 60 SPOF_BACAN .MEGK..ILIVDDQYGIRVLLHEVFQKEGYQTFQAANGFQALDIVKKDNPDLVVLDMKIPGMDGIEILKH SPOF_BACTK .MEGK..ILIVDDQYGIRVLLHEVFQKEGYQTFQAANGFQALDIVKKDNPDLVVLDMKIPGMDGIEIFKA SPOF_BACHA ..MNK..ILVVDDQYGIRVLLNEILQKDGYQMFQAANGIQALAIVEEETPDLVLLDMKIPGMDGLEILRR SPOF_PASTU MMNEKKLILIVDDQYAIRLLLKEIFSQDGIIVLQAAGGXEAIELVAQQQPDLMLLDMKMPGMDGIEILRR β4 α4 α5 70 80 90 100 110 120 . . . . . . SPOF_BACSU MKVIDENIRVIIMTAYGELDMIQESKELGALTHFAKPFDIDEIRDAVKKYLPLKSN SPOF_BACAN VKEIDESIKVILMTAYGELDMIQEAKDLGALMHFAKPFDIDEIRQAVRNELAVEA. SPOF_PASTU VRQVIPALKVIVMTAYGELEMMEKIRSLGVVMHFAKPFDVRAVRCGVLRYL..... SPOF_BACHA IKDMNPNIEVIMMTAYGELNMINEAMQLGAVTHFAKPFDIDDVRAVIAENMKSS.. SPOF_BACTK CKEIDESIKVILMSAYGELDMIQEAKDLGALMHFAKPFDIDEIRQAVRNELAVEA.