Scott Alan Smith, Ph.D., M.D.

Assistant Professor
Faculty Appointments
Assistant Professor of Medicine Assistant Professor of Pathology, Microbiology and Immunology
M.D., MEDICINE, University of Louisville, Louisville, KentuckyPh.D., University of Louisville, Louisville, KentuckyB.S., University of Louisville, Louisville, Kentucky
Office Address
1161 21st Avenue South
A2210 Medical Center North
Research Description
Symptomatic dengue virus infection ranges in disease severity from an influenza-like illness to life-threatening shock. One model of the mechanism underlying severe disease proposes that weakly cross-reactive antibodies induced during a primary infection facilitate virus entry into Fc receptor-bearing cells during a subsequent secondary infection, increasing viral replication and release of cytokines and vasoactive mediators, culminating in shock. This unique process, known as antibody-dependent enhancement of infection, has significantly hindered vaccine development. There is a concern that potent neutralizing antibodies must be generated to all four dengue virus serotypes, as a vaccine that induce weakly cross-reactive non-neutralizing antibodies may increase the likelihood of developing severe disease. Much of our understanding of this process has come from studies using mouse mAbs, however antibody responses in mice typically exhibit less complexity than those in humans. A better understanding of the humoral immune response to natural dengue virus infection in humans is sorely needed. Using a high-efficiency human hybridoma technology developed in our laboratory, it is now possible to generate human hybridomas reliably using B cells from the peripheral blood of individuals who have recovered from an infection. Employing this technology, we have generated over 250 hybridomas secreting human mAbs to dengue virus from subjects who had recovered from primary or secondary infection. The vast majority of these antibodies are broadly serotype cross-reactive, directed against either E or prM protein, and capable of antibody-mediated enhancement of infection in vitro; very few exhibited serotype-specific binding or potent neutralizing activity. By employing a flow cytometric neutralization screening approach, we were able to enrich in the numbers of potently neutralizing mAbs that can be identified. This tactic resulted in the identification of several major phenotypic groups of human mAbs, each exhibiting unique neutralization and functional properties. Interestingly, mAbs that display serotype specific, virion-only binding, and exhibit potent serotype specific neutralizing activity with little enhancing properties also are produced naturally by humans in response to infection. Understanding the epitopes and activity of these naturally-occurring human antibodies is critical for vaccine development. Ideally, the reactivity of epitopes bound by enhancing antibodies should be reduced or eliminated in candidate antigens during the rational development of a dengue vaccine, so as to discourage such dominant recognition of these antigenic features by the humoral immune response. The long-term goal is to use such molecular information in the rational design of dengue vaccines that enhance the induction of protective neutralizing antibodies and reduce the risk of development of severe disease.
Clinical Research Keywords
Dengue Virus, Vaccines, Immunology, Viral Pathogenesis
Messer WB, Yount BL, Royal SR, de Alwis R, Widman DG, Smith SA, Crowe JE, Pfaff JM, Kahle KM, Doranz BJ, Ibarra KD, Harris E, de Silva AM, Baric RS. Functional transplant of a DENV3-specific human monoclonal antibody epitope into DENV1. J. Virol [print-electronic]. 2016 Mar 3/9/2016; PMID: 26962223, PII: JVI.00155-16, DOI: 10.1128/JVI.00155-16, ISSN: 1098-5514.

Callaway JB, Smith SA, McKinnon KP, de Silva AM, Crowe JE, Ting JP. Spleen Tyrosine Kinase (Syk) Mediates IL-1ß Induction by Primary Human Monocytes during Antibody-enhanced Dengue Virus Infection. J. Biol. Chem [print-electronic]. 2015 Jul 7/10/2015; 290(28): 17306-20. PMID: 26032420, PMCID: PMC4498069, PII: M115.664136, DOI: 10.1074/jbc.M115.664136, ISSN: 1083-351X.

Smith SA, Silva LA, Fox JM, Flyak AI, Kose N, Sapparapu G, Khomandiak S, Ashbrook AW, Kahle KM, Fong RH, Swayne S, Doranz BJ, McGee CE, Heise MT, Pal P, Brien JD, Austin SK, Diamond MS, Dermody TS, Crowe JE. Isolation and Characterization of Broad and Ultrapotent Human Monoclonal Antibodies with Therapeutic Activity against Chikungunya Virus. Cell Host Microbe. 2015 Jul 7/8/2015; 18(1): 86-95. PMID: 26159721, PMCID: PMC4501771, PII: S1931-3128(15)00257-7, DOI: 10.1016/j.chom.2015.06.009, ISSN: 1934-6069.

Fibriansah G, Ibarra KD, Ng TS, Smith SA, Tan JL, Lim XN, Ooi JS, Kostyuchenko VA, Wang J, de Silva AM, Harris E, Crowe JE, Lok SM. DENGUE VIRUS. Cryo-EM structure of an antibody that neutralizes dengue virus type 2 by locking E protein dimers. Science. 2015 Jul 7/3/2015; 349(6243): 88-91. PMID: 26138979, PMCID: PMC4672004, PII: 349/6243/88, DOI: 10.1126/science.aaa8651, ISSN: 1095-9203.

Smith SA, Crowe JE. Use of Human Hybridoma Technology To Isolate Human Monoclonal Antibodies. Microbiol Spectr. 2015 Feb; 3(1): AID-0027. PMID: 26104564, DOI: 10.1128/microbiolspec.AID-0027-2014, ISSN: 2165-0497.

Smith SA, Nivarthi UK, de Alwis R, Kose N, Sapparapu G, Bombardi R, Kahle KM, Pfaff JM, Lieberman S, Doranz BJ, de Silva AM, Crowe JE. Dengue Virus prM-Specific Human Monoclonal Antibodies with Virus Replication-Enhancing Properties Recognize a Single Immunodominant Antigenic Site. J. Virol. 2015; 90(2): 780-9. PMID: 26512092, PMCID: PMC4702676, PII: JVI.01805-15, DOI: 10.1128/JVI.01805-15, ISSN: 1098-5514.

Callaway JB, Smith SA, Widman DG, McKinnon KP, Scholle F, Sempowski GD, Dittmer DP, Crowe JE, de Silva AM, Ting JP. Source and Purity of Dengue-Viral Preparations Impact Requirement for Enhancing Antibody to Induce Elevated IL-1ß Secretion: A Primary Human Monocyte Model. PLoS ONE. 2015; 10(8): e0136708. PMID: 26301593, PMCID: PMC4547738, PII: PONE-D-14-32063, DOI: 10.1371/journal.pone.0136708, ISSN: 1932-6203.

Fibriansah G, Tan JL, Smith SA, de Alwis R, Ng TS, Kostyuchenko VA, Jadi RS, Kukkaro P, de Silva AM, Crowe JE, Lok SM. A highly potent human antibody neutralizes dengue virus serotype 3 by binding across three surface proteins. Nat Commun. 2015; 6: 6341. PMID: 25698059, PMCID: PMC4346626, PII: ncomms7341, DOI: 10.1038/ncomms7341, ISSN: 2041-1723.

Smith SA, de Alwis AR, Kose N, Jadi RS, de Silva AM, Crowe JE. Isolation of dengue virus-specific memory B cells with live virus antigen from human subjects following natural infection reveals the presence of diverse novel functional groups of antibody clones. J. Virol [print-electronic]. 2014 Nov; 88(21): 12233-41. PMID: 25100837, PMCID: PMC4248927, PII: JVI.00247-14, DOI: 10.1128/JVI.00247-14, ISSN: 1098-5514.

de Alwis R, Williams KL, Schmid MA, Lai CY, Patel B, Smith SA, Crowe JE, Wang WK, Harris E, de Silva AM. Dengue viruses are enhanced by distinct populations of serotype cross-reactive antibodies in human immune sera. PLoS Pathog. 2014 Oct; 10(10): e1004386. PMID: 25275316, PMCID: PMC4183589, PII: PPATHOGENS-D-14-00771, DOI: 10.1371/journal.ppat.1004386, ISSN: 1553-7374.

Fibriansah G, Tan JL, Smith SA, de Alwis AR, Ng TS, Kostyuchenko VA, Ibarra KD, Wang J, Harris E, de Silva A, Crowe JE, Lok SM. A potent anti-dengue human antibody preferentially recognizes the conformation of E protein monomers assembled on the virus surface. EMBO Mol Med [print-electronic]. 2014 Mar; 6(3): 358-71. PMID: 24421336, PMCID: PMC3958310, PII: emmm.201303404, DOI: 10.1002/emmm.201303404, ISSN: 1757-4684.

Messer WB, de Alwis R, Yount BL, Royal SR, Huynh JP, Smith SA, Crowe JE, Doranz BJ, Kahle KM, Pfaff JM, White LJ, Sariol CA, de Silva AM, Baric RS. Dengue virus envelope protein domain I/II hinge determines long-lived serotype-specific dengue immunity. Proc. Natl. Acad. Sci. U.S.A [print-electronic]. 2014 Feb 2/4/2014; 111(5): 1939-44. PMID: 24385585, PMCID: PMC3918811, PII: 1317350111, DOI: 10.1073/pnas.1317350111, ISSN: 1091-6490.

Smith SA, de Alwis R, Kose N, Durbin AP, Whitehead SS, de Silva AM, Crowe JE. Human monoclonal antibodies derived from memory B cells following live attenuated dengue virus vaccination or natural infection exhibit similar characteristics. J. Infect. Dis [print-electronic]. 2013 Jun 6/15/2013; 207(12): 1898-908. PMID: 23526830, PMCID: PMC3654755, PII: jit119, DOI: 10.1093/infdis/jit119, ISSN: 1537-6613.

Smith SA, de Alwis AR, Kose N, Harris E, Ibarra KD, Kahle KM, Pfaff JM, Xiang X, Doranz BJ, de Silva AM, Austin SK, Sukupolvi-Petty S, Diamond MS, Crowe JE. The potent and broadly neutralizing human dengue virus-specific monoclonal antibody 1C19 reveals a unique cross-reactive epitope on the bc loop of domain II of the envelope protein. MBio. 2013; 4(6): e00873-13. PMID: 24255124, PMCID: PMC3870244, PII: mBio.00873-13, DOI: 10.1128/mBio.00873-13, ISSN: 2150-7511.

de Alwis R, Smith SA, Olivarez NP, Messer WB, Huynh JP, Wahala WM, White LJ, Diamond MS, Baric RS, Crowe JE, de Silva AM. Identification of human neutralizing antibodies that bind to complex epitopes on dengue virions. Proc. Natl. Acad. Sci. U.S.A [print-electronic]. 2012 May 5/8/2012; 109(19): 7439-44. PMID: 22499787, PMCID: PMC3358852, PII: 1200566109, DOI: 10.1073/pnas.1200566109, ISSN: 1091-6490.

Smith SA, Zhou Y, Olivarez NP, Broadwater AH, de Silva AM, Crowe JE. Persistence of circulating memory B cell clones with potential for dengue virus disease enhancement for decades following infection. J. Virol [print-electronic]. 2012 Mar; 86(5): 2665-75. PMID: 22171265, PMCID: PMC3302281, PII: JVI.06335-11, DOI: 10.1128/JVI.06335-11, ISSN: 1098-5514.

Krause JC, Tsibane T, Tumpey TM, Huffman CJ, Briney BS, Smith SA, Basler CF, Crowe JE. Epitope-specific human influenza antibody repertoires diversify by B cell intraclonal sequence divergence and interclonal convergence. J. Immunol [print-electronic]. 2011 Oct 10/1/2011; 187(7): 3704-11. PMID: 21880983, PMCID: PMC3178754, PII: jimmunol.1101823, DOI: 10.4049/jimmunol.1101823, ISSN: 1550-6606.

Ghebremariam YT, Smith SA, Anderson JB, Kahn D, Kotwal GJ. Intervention strategies and agents mediating the prevention of xenorejection. Ann. N. Y. Acad. Sci. 2005 Nov; 1056: 123-43. PMID: 16387682, PII: 1056/1/123, DOI: 10.1196/annals.1352.028, ISSN: 0077-8923.

Jha P, Smith SA, Justus DE, Kotwal GJ. Vaccinia virus complement control protein ameliorates collagen-induced arthritic mice. Ann. N. Y. Acad. Sci. 2005 Nov; 1056: 55-68. PMID: 16387677, PII: 1056/1/55, DOI: 10.1196/annals.1352.004, ISSN: 0077-8923.

Ganesh VK, Muthuvel SK, Smith SA, Kotwal GJ, Murthy KH. Structural basis for antagonism by suramin of heparin binding to vaccinia complement protein. Biochemistry. 2005 Aug 8/16/2005; 44(32): 10757-65. PMID: 16086578, DOI: 10.1021/bi050401x, ISSN: 0006-2960.

Reynolds DN, Smith SA, Zhang YP, Mengsheng Q, Lahiri DK, Morassutti DJ, Shields CB, Kotwal GJ. Vaccinia virus complement control protein reduces inflammation and improves spinal cord integrity following spinal cord injury. Ann. N. Y. Acad. Sci. 2004 Dec; 1035: 165-78. PMID: 15681807, PII: 1035/1/165, DOI: 10.1196/annals.1332.011, ISSN: 0077-8923.

Billings B, Smith SA, Zhang Z, Lahiri DK, Kotwal GJ. Lack of N1L gene expression results in a significant decrease of vaccinia virus replication in mouse brain. Ann. N. Y. Acad. Sci. 2004 Dec; 1030: 297-302. PMID: 15659810, PII: 1030/1/297, DOI: 10.1196/annals.1329.037, ISSN: 0077-8923.

Ganesh VK, Smith SA, Kotwal GJ, Murthy KH. Structure of vaccinia complement protein in complex with heparin and potential implications for complement regulation. Proc. Natl. Acad. Sci. U.S.A [print-electronic]. 2004 Jun 6/15/2004; 101(24): 8924-9. PMID: 15178763, PMCID: PMC428448, PII: 0400744101, DOI: 10.1073/pnas.0400744101, ISSN: 0027-8424.

Reynolds DN, Smith SA, Zhang YP, Lahiri DK, Morassutti DJ, Shields CB, Kotwal GJ. Vaccinia virus complement control protein modulates inflammation following spinal cord injury. Ann. N. Y. Acad. Sci. 2003 Dec; 1010: 534-9. PMID: 15033786, ISSN: 0077-8923.

Jha P, Smith SA, Justus DE, Kotwal GJ. Prolonged retention of vaccinia virus complement control protein following IP injection: implications in blocking xenorejection. Transplant. Proc. 2003 Dec; 35(8): 3160-2. PMID: 14698003, PII: S0041134503011400, ISSN: 0041-1345.

Smith SA, Sreenivasan R, Krishnasamy G, Judge KW, Murthy KH, Arjunwadkar SJ, Pugh DR, Kotwal GJ. Mapping of regions within the vaccinia virus complement control protein involved in dose-dependent binding to key complement components and heparin using surface plasmon resonance. Biochim. Biophys. Acta. 2003 Aug 8/21/2003; 1650(1-2): 30-9. PMID: 12922167, PII: S1570963903001894, ISSN: 0006-3002.

Kahn D, Smith SA, Kotwal GJ. Dose-dependent inhibition of complement in baboons by vaccinia virus complement control protein: implications in xenotransplantation. Transplant. Proc. 2003 Jun; 35(4): 1606-8. PMID: 12826233, PII: S0041134503004858, ISSN: 0041-1345.

Anderson JB, Smith SA, van Wijk R, Chien S, Kotwal GJ. Vaccinia virus complement control protein inhibits hyperacute xenorejection in a guinea pig-to-rat heterotopic cervical cardiac xenograft model by blocking both xenoantibody binding and complement pathway activation. Transpl. Immunol. 2003 Apr; 11(2): 129-35. PMID: 12799195, PII: S0966-3274(02)00149-1, DOI: 10.1016/S0966-3274(02)00149-1, ISSN: 0966-3274.

Anderson JB, Smith SA, van Wijk R, Chien S, Kotwal GJ. Vaccinia virus complement control protein ameliorates hyperacute xenorejection by inhibiting xenoantibody binding. Transplant. Proc. 2002 Dec; 34(8): 3277-81. PMID: 12493445, PII: S0041134502036928, ISSN: 0041-1345.

Smith SA, Krishnasamy G, Murthy KH, Cooper A, Bromek K, Barlow PN, Kotwal GJ. Vaccinia virus complement control protein is monomeric, and retains structural and functional integrity after exposure to adverse conditions. Biochim. Biophys. Acta. 2002 Jul 7/29/2002; 1598(1-2): 55-64. PMID: 12147344, PII: S0167483802003394, ISSN: 0006-3002.

Hicks RR, Keeling KL, Yang MY, Smith SA, Simons AM, Kotwal GJ. Vaccinia virus complement control protein enhances functional recovery after traumatic brain injury. J. Neurotrauma. 2002 Jun; 19(6): 705-14. PMID: 12165132, DOI: 10.1089/08977150260139093, ISSN: 0897-7151.

Anderson JB, Smith SA, Kotwal GJ. Vaccinia virus complement control protein inhibits hyperacute xenorejection. Transplant. Proc. 2002 Jun; 34(4): 1083-5. PMID: 12072283, PII: S0041134502028051, ISSN: 0041-1345.

Smith SA, Kotwal GJ. Immune response to poxvirus infections in various animals. Crit. Rev. Microbiol. 2002; 28(3): 149-85. PMID: 12385498, DOI: 10.1080/1040-840291046722, ISSN: 1040-841X.

Smith SA, Kotwal GJ. Virokines: novel immunomodulatory agents. Expert Opin Biol Ther. 2001 May; 1(3): 343-57. PMID: 11727510, DOI: 10.1517/14712598.1.3.343, ISSN: 1471-2598.

Murthy KH, Smith SA, Ganesh VK, Judge KW, Mullin N, Barlow PN, Ogata CM, Kotwal GJ. Crystal structure of a complement control protein that regulates both pathways of complement activation and binds heparan sulfate proteoglycans. Cell. 2001 Jan 1/26/2001; 104(2): 301-11. PMID: 11207370, PII: S0092-8674(01)00214-8, ISSN: 0092-8674.

Smith SA, Mullin NP, Parkinson J, Shchelkunov SN, Totmenin AV, Loparev VN, Srisatjaluk R, Reynolds DN, Keeling KL, Justus DE, Barlow PN, Kotwal GJ. Conserved surface-exposed K/R-X-K/R motifs and net positive charge on poxvirus complement control proteins serve as putative heparin binding sites and contribute to inhibition of molecular interactions with human endothelial cells: a novel mechanism for evasion of host defense. J. Virol. 2000 Jun; 74(12): 5659-66. PMID: 10823874, PMCID: PMC112054, ISSN: 0022-538X.