A lecture by the Srilankan team on dengue, vector borne viral infection.

12. Laboratory diagnostic criteria One of the following: 1. PCR + 2. Virus culture + 3. IgM seroconversion in paired sera 4. IgG seroconversion in paired sera or fourfold IgG titer increase in paired sera One of the following: 1. IgM + in a single serum sample 2. IgG + in a single serum sample with a HI titre of 1280 or greater Confirmed Highly suggestive

14. IgG antibody - specific to the initial infecting DV serotype + cross reacting antibody IgM antibody to the secondary infecting DV serotype Following primary infection – Specific antibody response + CMI (memory T cells) Cross reactive antibody response + CMI (memory T cells)

15. Pathogenesis – Role of cross reactive DV antibodies Cross reactive antibody binds to the infecting virus Form v- ab complexes. V- ab complexes attach to cells bearing receptors for the Fc portion of the ab Facilitates entry of the virus into these cells and the viral replication. Therefore, more cells are infected Increased immune response & release of cytokines

17. Cytokines secreted from infected macrophages and endothelial cells Cytokines secreted from activated T cells Exaggerated Cytokine response Endothelial dysfunction DV specific antibody interact with the endothelium DV infects endothelium and kills cells

22. Dengue Vaccine Candidates Approach Developer / Producer Subunit - 80% preM expressed in Drosophila S2 cell lines, +/- NS1, alum adjuvant Hawaii Biotech Genetically engineered, stable mutations in 3’ non-coding region of DENV-1, 2, 4 vaccine candidates. DENV-3 candidates = DENV-4/DEN-3 chimeras NIAID Laboratory of Infectious Diseases DENV-2 attenuated virus + 3 chimeras composed of DENV-2 non-structural genes + respective DENV 1,3, or 4 envelope genes CDC/InViragen Cell culture passage of clinical isolates WRAIR / GSK 4 chimeras composed of yellow fever 17D virus non-structural genes + respective DENV 1,2,3 or 4 envelope genes Acambis/ Sanofi Pasteur

23. Status of Dengue Vaccines ? Panacea Q3-2010 Butantan ? Biological E NIH Mid-2009 Tetravalent Acambis 2009 SanofiPasteur WRAIR ? Glaxo SmithKline Process Development Developer Phase IIB-III Phase II Phase I Evaluation Producer CDC Q1-2010 tetravalent InViragen Hawaii Biotech Q3-2009 monovalent 2010 - tetravalent Hawaii Biotech

28. Phylogenetic analysis of DV3 isolates from SL

30. Dengue serotypes (Source: Epid Unit & MRI) * MRI data Year Total Tested Total Positive D1 (%) D2 (%) D3 (%) D4 (%) 2006 1795 287 20 121 126 14 2007 461 56 01 26 20 00 2008 305 33 00 16 09 00 2009 264 49 19 10 15 00 * 2010 510 33 33 00 00 00 *2011 166 10 10 00 00 00

31. Distribution of A. albopictus Presence of A. albopictus before 1980 Areas invaded by A. albopictus since 1980 A. albopictus may become important in spreading the infection given it’s extensive distribution