Slide1: DENGUE VIRUS: NO ONE IS SAFE Caitlin Reed Smith College April 29, 2005 www.invivo.fiocruz.br/dengue/home_dengue.htm


Slide2: OVERVIEW OF THEMES Background Information Clinical Presentation & Diagnosis Biology Vaccination Prospects Public Health


WHAT IS DENGUE?: WHAT IS DENGUE? Flavivirus (type of arbovirus) Transmitted from Aedes aegypti and Aedes albopictus mosquitoes Four Serotypes (Dengue 1-4)


DENGUE (cont’d): DENGUE (cont’d) Three Manifestations: 1. Dengue Fever 2. Dengue Hemorrhagic Fever 3. Dengue Shock Syndrome Leads to death in 5% of cases More dangerous if infected second time by different serotype


WHY DO WE CARE ABOUT DENGUE?: WHY DO WE CARE ABOUT DENGUE? CDC Category A Infectious Disease Infects 50-100 million people every year About half the world lives in a “hot zone” Very hard to create vaccine Mosquito evolution = threat to U.S. Global warming http://klab.agsci.colostate.edu/aegypti/aegypti.html


WHY NOW?: WHY NOW? Failed eradication attempt in the Americas in 1970 Previously unestablished serotypes are establishing themselves in various countries Recent Outbreaks: 1. India, 2003 2. Hawaii, 2001 3. Taiwan, 2001 4. Puerto Rico, 1994-1995


WHERE IS DENGUE FOUND?: WHERE IS DENGUE FOUND? www.traveldoctoronline.net/diseases/dengue.htm


DENGUE TRANSMISSION : DENGUE TRANSMISSION


Slide9: Mosquitoes transmit dengue to human dendritic cells 2. Dengue targets areas with high WBC counts (liver, spleen, lymph nodes, bone marrow, and glands) 3. Dengue enters WBCs & lymphatic tissue 4. Dengue enters blood circulation http://phil.cdc.gov/PHIL_Images/08051999/00004/dengue_phf/sld006.htm HOW DENGUE SPREADS


CLINICAL PRESENTATION OF DENGUE: CLINICAL PRESENTATION OF DENGUE


SYMPTOMS OF DHF: SYMPTOMS OF DHF GRADE I: Fever with other symptoms such as vomiting, headache, muscle and joint pain: positive tourniquet test is the only evidence of hemorrhaging GRADE II: Grade I symptoms + spontaneous bleeding GRADE III*: Failure of circulatory system, clammy skin, rapid & weak pulse, restlessness GRADE IV*: Severe shock, no measurable blood pressure or pulse *Considered Dengue Shock Syndrome (DSS)


DENGUE GRADATION: DENGUE GRADATION http://w3.whosea.org/en/Section10/Section332/Section554_2564.htm


Slide13: http://www.cdc.gov/ncidod/dvbid/dengue/slideset/set1/images/petechiae2-small.jpg P E T E C H I A E


Slide14: P U R P U R A http://www.pediatrics.wisc.edu/education/derm/tutb/85m.jpg


Slide15: http://www-medlib.med.utah.edu/WebPath/ATHHTML/ATH036.html E C C H Y M O S I S


Slide16: http://www.cgste.mq/brainstorm/dengue/image/hemo.gif NASAL HEMORRHAGING


BIOLOGY OF DENGUE: BIOLOGY OF DENGUE http://www.stanford.edu/group/virus/flavi/2000/deng_em.jpg


BASIC BIOLOGY: BASIC BIOLOGY Single, positive-stranded RNA surrounded by an icosahedral core 90 glycoprotein E dimers overly M proteins Protein E is most important characteristic of dengue Modis, Ogata, Clements, et. al., 2004


BASIC DENGUE GENOME: BASIC DENGUE GENOME http://microvet.arizona.edu/Courses/MIC419/VaccProp05html/Dengue.html


FUSION PROTEIN E: FUSION PROTEIN E Modis, Ogata, et. al., 2004.


IMMUNE RESPONSE: IMMUNE RESPONSE http://www.ethal.org.my/opencms/opencms/ethal/Images/MedGeneralImages/Lymphocyte.jpg


FIRST INFECTION: FIRST INFECTION Humoral and cellular immune response - Ab serum neutralizing levels increase - T-lymphocytes activated by dendritic cells - Memory cells develop antibodies to fight off future infection of same serotype


SECOND INFECTION: SECOND INFECTION Antibody dependent enhancement - Enhancing immunoglobulin G (IgG) antibodies - Fc Receptors


CELLULAR LEVEL OF DENGUE FUSION : CELLULAR LEVEL OF DENGUE FUSION


ENTRY INTO CELL: ENTRY INTO CELL Dengue infection Endosome entry & pH change E protein conformational change Release of viral RNA into cell Replication & further infection


Slide26: PRE-FUSION POST-FUSION PROTEIN E CONFORMATIONAL CHANGE Modis, Ogata, et. al., 2004


PROTEIN E INSERTION INTO PM: PROTEIN E INSERTION INTO PM http://crystal.med.harvard.edu/cover_modis_vsmall.jpg Modis, Ogata, et. al., 2004.


VIRAL REPLICATION: VIRAL REPLICATION http://chen.bio.purdue.edu/images/flavi/viruslifecycle.jpg


TO SUMMARIZE…: TO SUMMARIZE… THE BODY’S RESPONSE TO A DENGUE INFECTION


DENGUE IN THE CELL: DENGUE IN THE CELL Dendritic cell infection  T-cell activation Previous infection = increase in viral load and decrease in incubation period ADE is problem for 20 years after first infection


PATHOGENIC STRATEGIES OF DENGUE : PATHOGENIC STRATEGIES OF DENGUE Invades circulatory system, causing: - vascular permeability - Disseminated intravascular coagulation - Potentially death http://www.ehu.es/biomoleculas/PROT/blood-clot.gif


DENGUE DIAGNOSIS: DENGUE DIAGNOSIS http://bensguide.gpo.gov/images/ben/ben_doctor.jpg


LABORATORY DIAGNOSIS OF DENGUE: LABORATORY DIAGNOSIS OF DENGUE METHODS: 1. Viral Isolation & Characterization 2. Genomic Sequencing 3. Antibody Detection www.synergene.net/de/images/dnasmall.jpg


VIRAL ISOLATION & CHARACTERIZATION: VIRAL ISOLATION & CHARACTERIZATION Old “Gold Standard” Cell Culture (mammals & mosquitoes) -Indirect Immunofluorescence Useful to study basic virology, epidemiology, and pathogenesis Impractical for rapid diagnosis & treatment http://www.cdc.gov/ncidod/dvbid/dengue/slideset/set1/image/virus-isolation-cell-culture2.jpg


GENOMIC SEQUENCING: GENOMIC SEQUENCING Quicker, more reliable means of diagnosis NASBA method (RNA-specific amplification assay) RT-PCR method to provide most accuracy, uses 5’-3’ nuclease oligonucleotide probe (which may not be able to distinguish among serotypes) – new “Gold Standard” Beware of false-positives due to contamination http://animal.intron.co.kr/Image/RT-pcr.gif


ANTIBODY DETECTION: ANTIBODY DETECTION Most common methods 1. Hemagglutinin inhibition test (HI test) 2. ELISA 3. Rapid immunochromatography test (commercial kits available) http://webdb.dmsc.moph.go.th/ifc_nih/applications/pics/Qualitative_test.jpg


STOPPING DENGUE: VACCINE DEVELOPMENT AND PUBLIC HEALTH STRATEGIES STOPPING DENGUE


MOST PROMISING VACCINE: MOST PROMISING VACCINE ChimeriVax-Dengue - Tetravalent - Uses yellow fever vaccine as base - 92% of monkeys passed “virulent virus challenge” Guirakoo, Pugachev, and Zhang, 2004


WHAT ABOUT HUMANS?: WHAT ABOUT HUMANS? Tetravalent vaccine ChimeriVax-Dengue? 20% seroconversion rate More research necessary! http://www.lung.ca/pneumonia/images/doc2.gif


PUBLIC HEALTH STRATEGIES : PUBLIC HEALTH STRATEGIES Vector Control Surveillance Preparation for outbreaks Research


Slide41: NON-BIOLOGICAL MEANS OF DECREASING THE INCIDENCE OF DENGUE


MOSQUITO NETS: w3.whosea.org/extrelations/ images/Bed%20net.jpg MOSQUITO NETS


NO MORE MOSQUITOES!: NO MORE MOSQUITOES! www.mosquitobarrier.com/ images/tincan.jpg


Slide44: www.headlice.org/ images/unsanitary.jpg ABOUT THAT STANDING WATER…


Slide45: “Children play in sewage in Nairobi's sprawling Mukuru Kaiyaba slum.” http://www.alertnet.org/thefacts/reliefresources/108273140124.htm


IMPEDIMENTS: IMPEDIMENTS Still lack complete understanding of dengue virus virulence Social/socioeconomic Travel spreads different serotypes Demographic changes Decentralized and therefore weak public health systems


REFERENCES: REFERENCES “Arthropod-borne Viruses Infection” http://virology-online.com/viruses/Arboviruses7.htm (accessed on April 2, 2005). “Bioterrorism Agents/Diseases” (2004). www.bt.cdc.gov/agent/agnetlist-category.asp (accessed on April 12, 2005). “Bleeding Into the Skin.” (2003). http://www.nlm.nih.gov/medlineplus/ency/article/003235.htm (accessed on April 12, 2005). “Capillary Fragility Test.” (1998). http://www.healthcentral.com/mhc/top/003395.cfm (accessed on April 5, 2005). CDC Dengue Fever Homepage. (2005). http://www.cdc.gov/ncidod/dvbid/dengue. (accessed on March 3, 2005). CDC Slideshow. (1999). “Dengue: Virus, Vector, and Epidemiology.” http://phil.cdc.gov/PHIL_Images/08051999/00004/dengue_phf/sld006.htm (accessed on April 1, 2005) Chambers, T.J., Y. Liang, D.A. Droll, J.J. Schlesinger, A.D. Davidson, P.J. Wright, X. Jiang (2003). Yellow Fever Virus/Dengue-2 Virus and Yellow Fever Virus/Dengue-4 Virus Chimeris: biological characterization, immunogenicity, and protection against dengue encephalitis in the mouse model. Journal of Virology. 77:3655-3668. “Dengue Triad.” (2005). http://www.healthatoz.com/healthatoz/Atoz/ency/dengue_fever.jsp. (accessed on March 31, 2005).


REFERENCES: REFERENCES “Dengue Virus Profile.” (2000). http://www.stanford.edu/group/virus/flavi/2000/dengue.htm. (accessed on April 4, 2005). Guirakhoo, F., K Pugachev, Z. Zhang, G. Myers, I. Levenbook, K. Draper, J. Lang, S. Ocran, F. Mitchell, M. Parsons, N. Brown, S. Brandler, C. Fournier, B. Barrere, F. Rizvi, A. Travassos, R. Nichols, D. Trent, and T. Monath. (2004). Safety and efficacy of chimeric yellow fever-dengue virus tetravalent vaccine formulations in nonhuman primates. Journal of Virology. 78:4761-4775. Halstead, S.B. (1988). Pathogenesis or dengue: challenges to molecular biology. Science. 239:476-481. “Hemorrhagic Fevers.” 2005. http://www.healthatoz.com/healthatoz/Atoz/ency/hemorrhagicfevers.jsp (accessed on April 3, 2005). Ho, L., J. Wang, M Shaio, C. Kao, D. Chang, S. Han, and J. Lai. (2001). Infection of human dendritic cells by dengue virus causes cell maturation and cytokine production. The Journal of Immunology. 166:1499-1506. Kalayanarooj, S. (1999). Standardized clinical management: evidence of reduction in dengue hemorrhagic fever child fatality rate in Thailand. Dengue Bulletin. 23. http://w3.whosea.org/en/section10/section332/section521_2449.htm (accessed on April 2, 2005).


REFERENCES: REFERENCES Kao, C., C. King, D. Chao, H. Wu, and G. Chang. (2005). Laboratory diagnosis of dengue virus infection: current and future perspectives in clinical diagnosis and public health. J. Microbiol. Immunol. Infect. 38: 5-16. Kuhn, R.J., W. Zhang, M.G. Rossmann, S.V. Pletney, J. Corver, E. Lenches, C.T. Jones, S. Mukhopadhyay, P.R. Chipman, E.G. Strauss, T.S. Baker, and J.H. Strauss. (2002). Structure of dengue virus: implications for flavivirus organization, maturation, and fusion. Cell Press. 108:717-725. Lai, P., S. Lee, C. Kao, Y. Chan, C. Huang, W. Lia, S. Wann, H. Lin, M Yen, and Y. Liu. (2004). Characteristics of a dengue hemorrhagic fever oubreak in 2001 in Kaohsiung. J. Microbiol. Immunolo. Infect. 37: 266-270. “Lymph Nodes.” www.cancerhelp.org.uk/cancer_images/nodesta.gif (accessed on April 1, 2005). Mady, B.J., D.V. Erbe, I. Kurane, M.W. Fanger, and F.A. Ennis. (1991). Antibody-dependent enhancement of dengue virus infection mediated by bispecific antibodies against cell surface molecules other than Fc gamma receptors. Journal of Immunology. 147:3139- 3144. Modis, Y., S. Ogata., D. Clements, S. Harrison. (2004). Structure of the dengue virus envelope protein after membrane fusion. Nature. 427:313-318. Perez, J., A Vorndam, and G. Clark. (2001). The dengue and dengue hemorrhagic fever epidemic in Puerto Rico, 1994-1995. Am. J. Trop. Med. Hyg. 64: 67-74. “Petechiae.” (2001). http://www.healthopedia.com/petechiae/ (accessed on April 3, 2005). Shepherd, S., P. Hinfrey, and W.H. Shoff. (2002). Dengue Fever. http://www.emedicine.com/MED/topic528.htm. (accessed April 12, 2005). Shrivastava, R. (2004). Dengue haemorrhagic fever: a global challenge. Indian Journal of Medical Microbiology. 22:5-6.


REFERENCES: REFERENCES Shu, P. and J. Huang. (2004). Current advances in dengue diagnosis. Clinical and Diagnostic Laboratory Immunology. 11:642-650. Stephenson, J. (2005). Understanding dengue pathogenesis: implications for vaccine design. Bulletin of the WHO. 83: 308-314. Sun, W., R. Edelman, N. Kanesa-Thasan, K.H. Eckels, J.R. Putnak, A.D. King, H. Houng, D. Tang, J. M. Scherer, C.H. Hoke, and B. Innis. 2003. Vaccination of human volunteers with monovalent and tetravalent live-attenuated dengue vaccine candidates. Am. J. Trop. Med. Hyg. 69: 24-31. “Thrombocytopenia.” (2005). http://www.nlm.nih.gov/medlineplus/ency/article/000586.htm (accessed on April 2, 2005). World Health Organization. (2002). Dengue: Strategic direction for research. www.who.int.tdr. (accessed on March 20, 2005). World Health Organization. (1999). Regional guidelines on dengue/DHF Prevention and Control: Clinical manifestations and diagnosis. http://w3.whosea.org/en/section10/section332/section554_2564.htm (accessed on April 1, 2005). Wilson, M. and L. Chen. (2002). Dengue in the Americas. Dengue Bulletin. 26: 44-61.