Current Research Projects
Antibodies are critical for protection against many diseases; however, they can also exacerbate dengue infection. Antibodies can enhance the ability of dengue virus to infect Fc receptor-bearing cells, potentially leading to more severe infection and disease in humans. This potential for antibodies to be beneficial or harmful in the face of a dengue infection has complicated the development of vaccines. We use a variety of methods such as the removal of specific antibody populations from immune sera, production of monoclonal antibodies from dengue-exposed people, and production of chimeric viruses to dissect the human antibody response to dengue. Current studies focus on mapping viral epitopes recognized by human antibodies and then defining their functional properties in cell culture and in vivo models. Our overall goal is to characterize the dengue-specific B-cell and antibody repertoire and then identify specific antibodies and immune mechanisms responsible for protective versus disease enhancing outcomes in people. Our collaborators in these studies are Ralph Baric at UNC, James Crowe at Vanderbilt, Sheemei Lok at Duke-NUS, Singapore, Eva Harris at UC-Berkeley and Carlos Sariol at the University of Puerto Rico.
These studies are supported by grants from the NIH.
A highly potent human antibody neutralizes dengue virus serotype 3 by binding across three surface proteins. Fibriansah G, Tan JL, Smith SA, de Alwis R, Ng TS, Kostyuchenko VA, Jadi RS, Kukkaro P, de Silva AM, Crowe JE, Lok SM. Nat Commun. 2015 Feb 20;6:6341. doi: 10.1038/ncomms7341. PMID: 25698059.
Dengue viruses are enhanced by distinct populations of serotype cross-reactive antibodies in human immune sera. de Alwis R, Williams KL, Schmid MA, Lai CY, Patel B, Smith SA, Crowe JE, Wang WK, Harris E, de Silva AM. PLoS Pathog. 2014 Oct 2;10(10):e1004386. doi: 10.1371/journal.ppat.1004386. eCollection 2014 Oct. PMID: 25275316.
Identification of human neutralizing antibodies that bind to complex epitopes on dengue virions. de Alwis R, Smith SA, Olivarez NP, Messer WB, Huynh JP, Wahala WM, White LJ, Diamond MS, Baric RS, Crowe JE Jr, de Silva AM. Proc Natl Acad Sci U S A. 2012 May 8;109(19):7439-44. doi: 10.1073/pnas.1200566109. Epub 2012 Apr 12. PMID: 22499787
Vaccination remains one of the most promising tools for preventing dengue virus infection. An ideal dengue vaccine would induce a durable active immune response against all dengue serotypes. The two main challenges to developing a vaccine are the presence of 4 distinct serotypes and the possibility of immune-enhanced dengue disease. We are currently expanding our knowledge about the properties of antibodies induced after natural infection, as well as those induced by dengue vaccines undergoing human clinical trials. Our collaborators on these studies are Ralph Baric at UNC, James Crowe at Vanderbilt, Eva Harris at UC-Berkely and the Gates Foundation Dengue Human Infection consortium.
These studies are supported by grants and contracts from the NIH, Gates Foundation and companies developing dengue vaccines.
Smith SA, de Alwis R, Kose N, Durbin AP, Whitehead SS, de Silva AM, Crowe JE (2013) Human monoclonal antibodies derived from memory B cells following live attenuated dengue virus vaccination or natural infection exhibit similar characteristics. Journal of Infectious Diseases 207: 1898-1908.
We have collaborated with colleagues in Sri Lanka for the past 20 years to understand the changing epidemiology of dengue on the island. We support the regular exchange of students and other researchers between UNC and Colombo to promote collaborative research and training activities. Our studies have led to the establishment of laboratory facilities for diagnostics and research in Sri Lanka, as well as the first population-based incidence rate estimates of dengue infection and disease in the region. Current studies are focused on understanding host and viral factors that influence clinical outcome. Our collaborators in Sri Lanka are the Genetech Research Institute, Medical Research Institute, Epidemiology Unit, Ministry of Health Sri Lanka and The Kotelawala Defense University.
These studies are currently supported by the European Union, The Sri Lankan Ministry of Health and The Sri Lankan National Science Foundation.
Corbett KS, Katzelnick L, Tissera H, Amerasinghe A, de Silva AD, de Silva AM, 2015. Preexisting Neutralizing Antibody Responses Distinguish Clinically Inapparent and Apparent Dengue Virus Infections in a Sri Lankan Pediatric Cohort. Journal of Infectious Diseases 211: 590-599. PMID: 25336728.
Tissera H, Amarasinghe A, De Silva AD, Kariyawasam P, Corbett KS, Katzelnick L, Tam C, Letson GW, Margolis HS, de Silva AM. Burden of dengue infection and disease in a pediatric cohort in urban Sri Lanka. Am J Trop Med Hyg. 2014 Jul 2;91(1):132-7. PMID: 24865684.
The clinical outcome of a dengue infection is dependent on both host and viral factors. Although all 4 serotypes of dengue can cause severe disease, genotype variation within each serotype results in strains linked to mild or subclinical infections whereas others are linked to severe infections. The actual viral genes, proteins, and phenotypes responsible for severe disease have not been identified. Through long-term epidemiological and viral phylogeny studies in Sri Lanka, we have identified distinct genotypes of DENV3 responsible for mild and severe disease epidemics. More recently, we have identified genotypes of DENV1 linked to mild and severe disease epidemics. Using natural viral isolates linked to different patterns of disease in people, we are currently exploring several ideas about dengue virus properties that may be responsible for different disease phenotypes. Our collaborators in this work include Nat Moorman at UNC, Alex Sette and Daniela Weisskopf and La Jolla Institute of Allergy and Immunology, Paba Paliyawardhana, Hasitha Tissera and Ananda Amerasinghe at the Epidemiology Unit, Ministry of Health Sri Lanka and Dharshan de Silva at Genetech Research Institute in Sri Lanka.
These studies are currently supported by grants from the NIH and UNC.
Tissera, HA; Ooi, EE; Gubler, DJ; Tan, Y; Logendra, B; Wahala, W; de Silva, AM; Abeysinghe, MRN; Palihawadana, P; Gunasena, S; Tam, CC; Amarasinghe, A; Letson, GW; Margolis, HS; de Silva, AD; (2011) New Dengue Virus Type 1 Genotype in Colombo, Sri Lanka. Emerging infectious diseases, 17 (11). pp. 2053-2055. ISSN 1080-6040 DOI: 10.3201/eid1711.101893
Messer, William B., Boyd Yount, Kari E. Hacker, Eric F. Donaldson, Jeremy P. Huynh, Aravinda M. De Silva, and Ralph S. Baric. “Development and characterization of a reverse genetic system for studying dengue virus serotype 3 strain variation and neutralization.” PLoS neglected tropical diseases 6, no. 2 (2012): e1486.
The leading dengue vaccines are based on tetravalent formulations (containing all four serotypes) of live, attenuated dengue viruses. It has been difficult to achieve a balanced protective response across all four serotypes using live vaccines. Safety is an issue with any live virus vaccine, perhaps even more so with dengue, as there is the risk of antibody-dependent enhancement stemming from a weak immune response against one serotype. We are currently working with a consortium of laboratories at UNC using nanoparticles to design and deliver tetravalent dengue vaccines. In our past work, we have found that many strongly neutralizing human antibodies against dengue also bind to complex quaternary structure epitopes displayed on the viral surface. Studies are underway using recombinant dengue proteins on the surface of nanoparticles to display neutralizing antibody epitopes, including these quaternary structure epitopes. Our collaborators are designing nanoparticles with optimal physical and chemical properties for targeting sites of immune activation. We are also testing different adjuvants to use with these nanoparticles to increase vaccine efficacy and safety. Our goal is to develop a new dengue vaccine platform that induces balanced and durable protective immune responses to all four serotypes. Our collaborators on these studies are the DeSimone, Ting, and Su laboratories at UNC, as well as the UNC Protein Expression Core headed by Mike Miley. Liquidia Technologies Inc is our industry partner in these translational studies.
These studies are supported by a grant from the NIH.