The main focus of our research group is equine disease caused by Streptococcus equi (Strangles) and the closely related S. zooepidemicus (Pneumonia). Research objectives include development of a safer more effective strangles vaccine and economic, rapid and sensitive methods of detection of S. equi in clinical specimens. Proteins with partial or complete amino sequence unique to S. equi are being studied with regard to their roles in virulence, binding to host molecules on epithelium and platelets, and generation of protective and diagnostic immune responses. These studies have resulted in a number of diagnostically useful applications including laboratory-based SeM-specific ELISA and PCR detection of S. equi. Rapid and sensitive methods of detecting S. equi in clinical specimens are also being developed based on helicase dependent DNA amplification or SeM specific antibody capture on lateral-flow platforms.
Changes in capsule expression and surface and secreted protein profiles of S. zooepidemicus associated with its transformation to the virulent invasive phenotype responsible for acute necrotizing/hemorrhagic pneumonia are being investigated to better understand its pathogenesis and perhaps identify potential vaccine components. Selected recombinant proteins are being evaluated as protective antigens in ponies.
Finally, involvement of bacteriophage in the evolution of S. equi from S. zooepidemicus and transduction of virulence factors is also an interest of our laboratory. This information may be helpful in forecasting appearance of strains of S. equi with enhanced pathogenicity.
Timoney, John. F., Aiping Qin, Suresh Muthupalani and Sergey Artiushin. 2007. Vaccine potential of novel surface exposed and secreted proteins of Streptococcus equi. Vaccine 25:5583-5590.
Timoney, J.F. and P. Kumar. 2008. Early pathogenesis of equine Streptococcus equi infection (strangles). Equine Veterinary Journal 40:637-642.
Timoney, J.F. 2009. Strangles: Immunology and Management. In: N. Edward Robinson and Kim A. Sprayberry (Eds). Current Therapy in Equine Medicine 6. Saunders/Elsevier pp. 124-8.
Timoney, J.F., R. DeNegri, A. Sheoran and N. Forster, 2010. Affects of N-terminal variation in the SeM protein of Streptococcus equi on antibody and fibrinogen binding. Vaccine 26:1522-7.
Velineni, S., Timoney, J.F. 2013. Identification of novel immunoreactive proteins of Streptococcus zooepidemicus with potential as vaccine components. Vaccine 31(38):4129-35.
Velineni, S., Breathnach, C.C., Timoney, J.F. 2014. Evidence of lateral gene transfer among strains of Streptococcus zooepidemicus in weanling horses with respiratory disease. Infect Genet Evol. 21:157-60.
Velineni, S., Timoney, J.F. 2015. Capsular hyaluronic acid of equine isolates of Streptococcus zooepidemicus is upregulated at temperatures below 35°C. Equine Vet J. 47(3):333-8.
Our research program aims at gaining a better understanding of leptospira infection in the pregnant mare, fetus and eyes of horses affected with moon blindness. The long-term goals are discovery of methods of prevention by immunization, rapid diagnosis, and serovar identification in clinical specimens. Using expression gene libraries of Leptospira interrogans serovar Pomona type kennewicki, we have identified a set of novel proteins including Lig A, LruA, B, C, LfhA and sphingomyelinase Lk73.5 some of which are expressed only in vivo and all of which induce antibody responses in serum or the eye. In vivo induced proteins are proving valuable as reagents to measure antibody responses that may correlate with long-term protection and distinguishing vaccine from infection response. Coding sequences of some of these proteins are also being used in development of novel PCR based tests for leptospira in horse urine and in kidney/urine of wildlife with potential as sources of leptospira for the horse.
Artiushin, S., J.F. Timoney, J. Nally, and A. Verma. 2004. Host-inducible immunogenic sphingomyelinase-like protein, Lk73.5 of Leptospira interrogans. Infect. Immun. 72:742-49.
Verma, A., S. Artiushin, J. Matsunaga, D.A. Haake and J.F. Timoney. 2005. LruA and LruB, novel lipoproteins of pathogenic Leptospira interrogans associated with equine recurrent uveitis. Infect Immun. 73:7259-66.
Verma, A., J. Hellwage, S. Artiushin, P.F. Ziffel, P. Kraiczy, J.F. Timoney and B. Stevenson. 2006. LfhA a novel factor H-binding protein of Leptospira interrogans. Infect. Immun. 74:2659-66.
Verma, A., D. Kumar, K. Babb, J.F. Timoney and B. Stevenson. 2010. Cross-reactivity of antibodies against leptospiral recurrent uveitis-associated proteins A and B (Lru A and B) with eye proteins. Plos Negl Trop Dis, Aug 3:4(8)e778.
Timoney, J.F., Kalimuthusamy, N., Velineni, S., Donahue, J.M., Artiushin, S.C., Fettinger, M. 2011. A unique genotype of Leptospira interrogans serovar Pomona type kennewicki is associated with equine abortion. Vet Microbiol. 150(3-4):349-53.
Vedhagiri, K., Velineni, S., Timoney, J.F., Shanmughapriya, S., Vijayachari, P., Narayanan, R., Natarajaseenivasan, K. 2013. Detection of LipL32-specific IgM by ELISA in sera of patients with a clinical diagnosis of leptospirosis. Pathog Glob Health. 107(3):130-5.
Nasopharyngeal Mucosal Immune Response
The microscopic, histochemical and ultrastructural features of the equine tonsillar complex have been characterized as a basis for studies of attachment, penetration, survival and immune mediated elimination of Streptococcus equi. The role of local immune responses on N terminal amino acid sequence variation of the SeM protein of S. equi has been investigated using monoclonal antibodies and pepset analysis. We are also exploring methods of stimulating nasopharyngeal mucosal immune responses in the horse including intranasal instillation of fusions of Se18.9, a potent equine mucosal immunogen, as delivery vehicles.
Kumar, P., J.F. Timoney and A.S. Sheoran. 2001. M cells and associated lymphoid tissue of the equine nasopharyngeal tonsil. Equine Vet. J. 33:324-330.
Kumar, P. and J.F. Timoney. 2005. Histology and ultrastructure of the equine lingual tonsil. Crypt epithelium and associated structures. Anal. Hist. Embryol. 34:27-33.
Timoney, J.F. and P. Kumar. 2008. Early pathogensis of equine Streptococcus equi infection (strangles). Equine Vet. J. 40:637-42.
Clostridial Enterocolitis of Foals
Field trials of a Clostridium perfringens autogenous bacterin supplemented with recombinant β2 toxin are ongoing to determine its protective efficacy for newborn foals following prepartum vaccination. Such a vaccine potentially could reduce the incidence of diarrhea caused by toxigenic Clostridium perfringens in foals in the first weeks of life. In another project with a similar goal we have cloned the cell binding regions of the A and B toxins of Clostridium difficile to determine whether these parts of the toxins might be useful to supplement an experimental bacterin for prepartum vaccination of mares. Enterocolitis associated with Cl. difficile is an emerging and serious disease of neonatal foals on Kentucky farms.
Timoney, J.F., M. Hartmann, L. Fallon, E. Fallon and J. Walker. 2005. Antibody responses of mares to prepartum vaccination with Clostridium perfringens bacterin supplemented with recombinant β2 toxin. Vet. Rec. 157:810-11.