Steven M. Szczepanek

Atwater Laboratory, Room A-110 (Lab A-144)
Telephone: (860) 486-8101

Courses Taught

  • PVS 3700: Emerging Infectious Diseases
  • PVS 5632: Vaccines: Mechanisms of Immune Protection

Research Interests

Impaired Immunity in Sickle Cell Disease

Waning long-term immunity after vaccination with the pneumococcal vaccine Prevnar-13
Early mortality and recurrent hospitalizations due to invasive pneumococcal disease (Streptococcus pneumoniae infection) are common for people with Sickle Cell Disease (SCD). Frequent pneumococcal vaccinations are administered to SCD patients in the US, reducing infections and increasing patient life expectancy.  Unfortunately, recent research indicates that the currently licensed pneumococcal vaccines are not as effective in patients with SCD, which is associated with low antibody titers shortly after vaccination. Our group has shown that mice with SCD are not protected from infection after pneumococcal vaccination. Much like in SCD patients, we correlated this lack of protection with short-lived pneumococcal antibody titers after vaccination.  An important finding from this work is that antibody titers do not recover after booster shots are given to SCD mice, indicating that there is a deficiency in the generation of both B-cell memory and long-lived plasma cells (which produce antibodies). Further compounding this problem, it has been shown that protective pneumococcal vaccine responses require specialized B-cells in the spleen and peritoneal cavity called B-1 B-cells, and we have previously shown that SCD mice have dramatically reduced numbers of B-1 cells in their spleens. We also observed reduced percentages of these cells in the blood of SCD patients when compared to healthy control subjects. Hence, we have found cellular and functional correlates in the SCD mouse model that may explain the reduced effectiveness of pneumococcal vaccines and increased susceptibility to infection in people with SCD. We are currently working on trying to understand the basic mechanism of impaired pneumococcal immunity in SCD mice with the aim of developing new vaccines and therapeutics to overcome this problem.    
Exhaustion and impaired B-cell memory induction in response to Influenza virus vaccination
Severe disease due to infection with the pandemic H1N1 influenza virus became pronounced in people with SCD in 2009. Unfortunately, little work has been done to understand the immunological effectiveness of the influenza vaccine in adults with SCD so that such problems can be avoided in the future. After conducting a clinical study, we have found that many SCD subjects do not induce the production of hemagglutination inhibition (HI) titers after influenza vaccination, whereas Control subjects do. Flow cytometric analysis of the blood leukocytes has revealed that Control subjects induced B-cells to shift towards a memory phenotype, but this was again inconsistent among the SCD subjects. B-cells also appear to have higher expression of FcRL4 in SCD subjects, indicating that they may have an exhausted phenotype. Additional observations of baseline aberrations included elevated serum concentrations of the neutrophil chemokine GRO and the “pro-inflammatory antibody” IgG3. We are interested in pursuing the potential link between inhibition of B-cell memory induction and exhaustion in patients with SCD after influenza vaccination, with the goal of reformulating vaccines such that they increase long-term memory against this virus.
Vaccine safety and exaggerated inflammation
Recent studies have indicated that severe adverse reactions to vaccines containing the adjuvant aluminum hydroxide (Alum) may be occurring in SCD patients after inoculation. We have found that SCD mice experience high mortality almost immediately after vaccination with ovalbumin and Alum, which is associated increased levels of IL-1b, IL-6, and total protein in the bronchoalveolar lavage fluid (BALF) in these mice. These findings are akin to those observed in acute respiratory distress syndrome (ARDS). We are currently looking into mediators of inflammation as a possible cause of over-exuberant responses to Alum containing vaccines so that we can better understand how and why severe adverse reactions to vaccination are occurring in SCD patients.

Foot-and-Mouth Disease Vaccine Development

Viral variants and sub-serotypes found in Foot and Mouth Disease Virus (FMDV) pose immense problems for vaccine developers, as existing vaccines provide inadequate cross protection. We have shown in mice that “xenoepitope substitution” of the immunodominant and highly mutable epitope found in the VP1 G-H loop results in immune refocusing to other (sub-dominant) epitopes. We are currently working with collaborators at Plum Island Animal Disease Center (PIADC) to test the current Ad5-FMD vaccine consturcted with xenoepitopes in the hypervarialbe region of the G-H loop in swine, with the aim to broaden immunity to multiple strains of the virus.


Peer-reviewed Publications

  1. Szczepanek SM, Roberts S, Rogers K, Cotte C, Adami AJ, Bracken SJ, Salmon S, Secor Jr. ER, Thrall RS, Andemariam B, Metzger DW. “Poor Long-term Efficacy of Prevnar-13 in Sickle Cell Disease Mice is Associated with an Inability to Sustain Pneumococcal-specific Antibody Titers”. PLoS One. Feb 24, 2016. PMID:26910228
  2. Bracken SJ, Adami AJ, Szczepanek SM, Ehsan M, Natarajan P, Guernsey LA, Rafti E, Matson AP, Schramm CM, Thrall RS. “Long-term exposure to house dust mite antigen leads to suppression of allergic airway sisease sespite persistent lung inflammation”. Int Arch Allergy Immunol. 2015;166(4):243-58. PMID:25924733
  3. Spotlight Article: Szczepanek SM, Boccaccio M, Pflaum K, Liao X, Geary SJ. “Hydrogen Peroxide Production from Glycerol Metabolism is Dispensable for the Virulence of Mycoplasma gallisepticum in the Tracheas of Chickens” Infect Immun. 2014 Dec; 82(12):4915-4920. PMID:25156740
  4. Secor ER Jr., Szczepanek SM, Matson A, Rafti E, Guernsey L, Natarajan P, McNamera JT, Schramm CM, Thrall RS, Silbart LK. “Bromelain Inhibits Allergic Sensitization and Murine Asthma via Modulation of Dendritic Cells”. 2013;2013:702196. PMCID: PMC3870104
  5. Bautista EJ, Zinski J, Szczepanek SM, Johnson E, Tulman ER, Ching W, Geary SJ, Srivastava R. “Semi-automated curation of metabolic models via flux balance analysis: a case study with Mycoplasma gallisepticum”. PLoS Comput Biol. 2013 Sept;9(9):e1003208. PMCID: PMC3764002
  6. Szczepanek SM, Secor ER Jr., Bracken SJ, Guernsey L, Rafti E, Matson A, Thrall RS, Andemariam B. “Transgenic Sickle Cell Disease Mice have High Mortality and Dysregulated Immune Responses After Vaccination”.Pediatr Res. 2013 Aug;74(2):141-7. PMID:23728384
  7. Szczepanek SM, McNamara JT, Secor ER, Natarajan P, Guernsey LA, Miller L, Ballesteros E, Jellison E, Thrall RS, Andemariam B. “Splenic Morphologic Alterations are Accompanied by Altered Baseline Immunity in a Mouse Model of Sickle Cell Disease”. Am J Pathol. 2012. 181(5):1725-34. PMCID: PMC3483810
  8. Secor ER, Szczepanek SM, Singh A, Guernsey L, Natarajan P, Rezaul K, Han DK, Thrall RS, Silbart LK. “LC-MS/MS Identification of a Bromelain Peptide Biomarker from Ananas comosus Merr”. 2012;2012:548486. PMCID: PMC3467939
  9. Tulman ER, Liao X, Szczepanek SM, Ley DH, Kutish GF, Geary SJ. “Extensive variation in surface lipoprotein gene content in a novel Mycoplasma gallisepticum strain associated with the North American house finch epizootic”. Microbiology 2012. 158(Pt 8):2073-88. PMID: 22628486
  10. Szczepanek SM, Barrette RW, Rood D, Alejo D, Silbart LK. “Xenoepitope Substitution Avoids Deceptive Imprinting and Broadens the Immune Response to Foot-and-Mouth Disease Virus”. Clin Vaccine Immunol. 2012. 19(4):461-7. PMCID: PMC3318270
  11. Szczepanek SM, Majumder S, Sheppard, ES, Liao X, Rood D, Tulman ER, Wyand S, Krause DC, Silbart LK, Geary SJ. “Vaccination of BALB/c Mice with an Avirulent Mycoplasma pneumoniae P30 Mutant Results in Disease Exacerbation Upon Challenge with a Virulent Strain”. Infect Immun. 2012. 80(3):1007-14. PMCID: PMC3294651
  12. May M, Szczepanek SM, Frasca S. Jr., Gates AE, Demcovitz D, Moneypenny C, Brown DR, Geary, SJ. “Effect of Sialidase Knockout and Complementation on Mycoplasma gallisepticum Cytadherence and Virulence”.Vet Micro. 2012. 157(1-2):91-5. PMID: 22197303
  13. Challa S, Szczepanek SM, Rood D, Barrette RW, Silbart LK. “Bacterial Toxin Fusion Proteins Elicit Mucosal Immunity Against a Foot-and-Mouth Disease Virus Antigen When Administered Intranasally to Guinea Pigs”. Advances in Virology. 2011; 2011:713769. PMCID: PMC3265312
  14. Barrette RW, Szczepanek SM, Rood D, Challa S, Avery N, Vajdy M, Kramer E, Rodriguez L, Silbart LK. “Use of inactivated E. coli enterotoxins to enhance respiratory mucosal adjuvanticity during vaccination in swine”. Clin Vaccine Immunol. 2011 Nov;18(11):1996-8. PMID:21918121
  15. Szczepanek SM, Frasca S Jr., Schumacher VL, Liao X, Padula M, Djordjevic SP, Geary SJ. “Identification of Lipoprotein MslA as a Neoteric Virulence Factor of Mycoplasma gallisepticum”. Infect Immun. 2010 78(8):3475-83. PMCID: PMC2916287
  16. Szczepanek SM, Tulman ER, Gorton TS, Liao X, Lu Z, Zinski J, Aziz F, Frasca S Jr., Kutish GF, Geary SJ.    “Comparative Genomic Analyses of Attenuated Strains of Mycoplasma gallisepticum”. Infect Immun. 2010 78(4):1760-71. PMCID: PMC2849401

Non-peer-reviewed Publications and Book Chapters

  1. Mollicutes: Molecular Biology and Pathogenicity” – Browning GF - Editor Chapter: Host Immune Responses to Mycoplasmas; Szczepanek SM & Silbart LK. 2nd ed., 2014, Caister Academic Press NY, NY.
  2. Szczepanek SM and Geary SJ.  “Mycoplasma gallisepticum Hydrogen Peroxide-Induced Cytotoxicity and Virulence: Lack of Correlation in the Natural Host”. [Published with Spotlight Article #14]. Infect Immun. 2014 Dec; 82(12):4914.
  3. Szczepanek SM and Secor ER Jr. “Echinacea; Have Translational Research Outcomes Altered the Way You Prescribe this Antibacterial and Immune-modulating Phytotherapeutic?”. Naturopathic Doctor. 2013, Feb.


  1. The Daily Campus. Feburary 2016.
  2. USDA Press Release. August 2015.  
  3. Naturally@UConn. August 2015.
  4. UConn Today. June 2015.
  5. Naturally@UConn. January 2015.

Contact Us

Pathobiology and Veterinary Science
College of Agriculture, Health and Natural Resources
61 North Eagleville Road, Unit-3089
Telephone: (860) 486-4000
Fax: (860) 486-2794