Research Molecular evaluation of vector-borne pathogen infections: Our research is focused on characterizing vector-borne pathogens, particularly tick-transmitted rickettsial disease agents, Ehrlichia chaffeensis and Ehrlichia canis. We use the tools of molecular biology, immunology, animal models and cell culture systems. E. chaffeensis is the agent causing human monocytic ehrlichiosis (HME). It also infects dogs, white-tailed deer, goats and coyotes. E. canis is primarily responsible for the canine monocytic ehrlichiosis. It is endemic throughout the world, except Australia. These closely related pathogens remain in both arthropod and vertebrate hosts for long periods of time. This strategy may aid them in their parasitic lifestyle. Determining the molecular basis for persistence by these bacteria of the genus Ehrlichia will be important in order to accomplish our long range goals of developing effective methods of control against these tick-borne pathogens. Our research is focused on understanding the pathogen evasion mechanisms. Specifically, we study to define the protective host-immune response needed to eliminate the infection. We also study to define how these rickettsiales evade host responses in both vertebrate and tick hosts in order to support their life cycle. Selected publications Vijayakrishna Singu, Lalitha Peddireddi, Kamesh R. Sirigireddy, Chuanmin Cheng and Roman R. Ganta. Unique microphage and tick cell-specific protein expression from the p28/p30-outer membrane protein multigene locus in Ehrlichia chaffeensis and Ehrlichia canis. Cell. Microbiol. (2006) (In press). Kamesh R. Sirigireddy and Roman R. Ganta. Multiplex Detection of Ehrlichia and Anaplasma species pathogens in Peripheral Blood by Real-Time RT PCR. The Journal of Molecular Diagnostics., 7, 308-316 (2005). Vijayakrishna Singu, Haijie Liu, Chuanmin Cheng and Roman R. Ganta. Ehrlichia chaffeensis expresses macrophage and tick cell-specific 28 kDa outer membrane proteins. Infect. Immun. 73, 79-87 (2005). Chanran K. Ganta, Ning Lu, Brian G. Helwig, Frank Blecha, Roman R. Ganta, Ling Zheng, Chris Ross, Tim I. Musch, Richard J. Fels, Michael J. Kenney. Central Angiotensin II-enhanced splenic cytokine gene expression is mediated by the sympathetic nervous system. Am J Physiol Heart Circ Physiol. 289, 683-691 (2005). Roman R. Ganta, Chuanmin Cheng, Melinda J. Wilkerson and Stephen K. Chapes. Delayed clearance of Ehrlichia chaffeensis infection in CD4+ T-cell knockout mice. Infect. Immun. 72, 159-167 (2004). Chanran K. Ganta, Frank Blecha, Roman R. Ganta, Brian G. Helwig, Sujatha Parimi, Ning Lu, Richard J. Fels, Tim I. Musch, Michael J. Kenney. Hyperthermia-enhanced splenic cytokine gene expression is mediated by the sympathetic nervous system. Physiol Genomics. 19, 175-183 (2004). Chuanmin Cheng, Christopher D. Paddock, and Roman R. Ganta. Molecular Heterogeneity of Ehrlichia chaffeensis Isolates as Determined by the Sequence Analysis of 28 kDa Outer Membrane Protein Genes and Other Regions of the Genome. Infect. Immun., 71, 187-195 (2003) Roman R. Ganta. All you need to know about nematodes (Book Review). Trends Parasitol. 18, 517 (2002). Roman R. Ganta, M. Wilkerson, C. Cheng, A. Rokey, and S. K. Chapes. Persistent Ehrlichia chaffeensis .Infection Occurs in the Absence of Functional MHCII Genes. Infect Immun., 70, 380-388, (2002). A.F. Barbet, W.M. Whitmire, S.M. Kamper, B.H. Simbi, Roman R. Ganta, A.L. Moreland, D.M.Mwangi, T.C. McGuire, S.M. Mahan. A subset of rickettsial genes important for immune recognition and protection. Gene 275, 287-298 (2001). J. S. Li, E. Yager, M. Reilly, C. Freeman, G. R. Reddy, F. K. Chu, and G. Winslow. Outer membrane protein specific monoclonal antibodies protect SCID mice from fatal infection by the obligate intracellular bacterial pathogen Ehrlichia chaffeensis.J. Immunol. 166, 1855-1862, (2001). K. J. Watts, G. R. Reddy, R. A. Holmes, J. B. Lok, D. H. Knight, G. A. Smith and C.H. Courtney. Seasonal prevalence of third-stage larvae of Dirofilaria immitis in mosquitoes from Florida and Louisiana.J. Parasitol., 87, 322-329 (2001). G. R. Reddy and C. P. Streck. Variability in the 28-kDa surface antigen protein multigene locus of isolates of the emerging disease agent Ehrlichia chaffeensis suggests that it plays a role in immune evasion. Molecular Cell Biology Res. Commun., 1, 167-175 (1999). M. V. Bowie, G. R. Reddy, S. M. Semu, S. M. Mahan, and A.F. Barbet. Potential value of major antigenic protein 2 (MAP2) for serological diagnosis of heartwater and related Ehrlichial infections. Clin.Diag. Lab. Immunol., 6:209-215 (1999). Watts, K.J., C.H. Courtney, and G. R. Reddy. Development of PCR and probe-based test for the sensitive and specific detection of of Dirofilari immitis. Mol. Cell. Probes, 14, 425-430 (1999). G. H. Salem, X. J. Liu, J. D. Johnsrude, J. B. Dame, and G. R. Reddy. Development and evaluation of an extra chromosomal DNA-based PCR test for diagnosing bovine babesiosis. Mol. Cell. Probes, 13,107-113 (1999). G. R. Reddy, C. R. Sulsona, A. F. Barbet, S. M. Mahan, M. J. Burridge and A. R. Alleman. Molecular characterization of a 28 kDa surface antigen gene family of the tribe Ehrlichiae. Biochem. Biophy. Res.Commun., 247, 636-643 (1998). R. M. Kaplan, John B. Dame, G. R. Reddy and C. H. Courtney. The prevalence of Fasciola hepatica in its snail intermediate host determined by DNA probe assay. Int J. Parasitol., 27, 1585-1593, (1997). G. R. Reddy, C. R. Sulsona, R. H. Herrison, S. M. Mahan, M. J. Burridge and A. F. Barbet. Sequence heterogeneity of the Major Antigenic Protein 1 genes from Cowdria ruminantium isolates from different geographical areas. Clin. Diag. Lab. Immunol., 3, 417-422 (1996). J. A. M. Calder, G. R. Reddy, L. Chieves, C. H. Courtney, R. Littell, J. Livingood, R.I.A. Norval, C.Smith, and J. B. Dame. Monitoring Babesia bovis infections in cattle using PCR-based tests. J. Clin.Microbiol. 34, 2748-2755 (1996). J.D. Dame, P. Bourke, D. Chakrabarti, Z. Christodoulou, R. Coppel, A. Cowman, A. Craig, J. Foster, N.Goodman, A. Holder, D. Holt, D. Kemp, M. Lanzer, A. lim, C. Newbold, J.V. Ravetz, G. R. Reddy, J.Rubio, S.M. Schuster, X. Su, J.K. Thompson, T. Wellems, and E. Werner. Current status of the Plasmodium falciparum genome project. Mol. Biochem. Parasitol., 79, 1-12 (1996). R. M. Kaplan, John B. Dame, G. R. Reddy and C. H. Courtney. A repetitive DNA probe for sensitive detection of Fasciola hepatica infected snails. Int J. Parasitol, 25, 601-610, (1995). G. R. Reddy. Determining the sequence of parasite DNA (Review). Parasitology Today, 11, 37-42 (1995). G. R. Reddy. Cloning and characterization of a Plasmodium falciparum cyclophilin gene that is stage specifically expressed. Mol. Biochem. Parasitol., 73, 111-121 (1995). J. B. Dame, G. R. Reddy, C. A. Yowell, B. M. Dunn, J. Kay an C. Berry. Sequence, expression and modeled structure of an aspartic protease from the human malaria parasite Plasmodium falciparum. Mol.Biochem. Parasitol., 64, 177-190 (1994). D. Chakrabarti, G. R. Reddy, J. B. Dame, E. C. Almira, P. J. Lapis, R. J. Ferl, T. P. Yang, T. C. Rowe and S. M. Schuster. Analysis of expressed sequence tags from Plasmodium falciparum. Mol. Biochem.Parasitol., 66, 97-104 (1994). G. R. Reddy, D. Chakrabarti, S. M. Schuster, R. J. Ferl, E. C. Almira and John B. Dame. Gene sequence tags from Plasmodium falciparum genomic DNA fragments prepared by the "genease" activity of mung bean nuclease. Proc. Natl. Acad. Sci. (USA). 90, 9867-9871, (1993). G. R. Reddy, P. A. Vasanen, P. M. Sharma, R. Kohani, J. L. Johnson, A. K. Raney, B. M. Babior and A.McLachlan. Cloning and characterization of the human muscle phosphofructokinase gene. DNA and Cell Biology 11, 461-470, (1992). G. R. Reddy and J. B. Dame. Ribosomal RNA based method for sensitive detection of Babesia bigemina in bovine blood.. J. Clin. Microbiol. 30, 1811-1814, (1992). G. R. Reddy, D. Chakrabarti, C. A. Yowell and J. B. Dame. Sequence microheterogeneity of the three small subunit ribosomal RNA genes of Babesia bigemina: Expression in erythrocyte culture. Nucl. Acids Res. 19, 3641-3645, (1991). P. M. Sharma, G. R. Reddy, B. M. Babior, and A. McLachlan. Alternative splicing of the transcript encoding the human muscle isozyme of phosphofructokinase. J. Biol. Chem., 265, 9006-9010, (1990). P. M. Sharma, G. R. Reddy, S. Vora, B. M.Babior and A. McLachlan. Cloning and expression of the human muscle phosphofructokinase cDNA. Gene 77, 177-183, (1989). J. W. Harvey and G. R. Reddy. Postnatal hematological development in phosphofructokinase-deficient dogs. Blood, 74, 2556-2561, (1989). G. R. Reddy, and A. Ramaiah. Purification of rabbit liver phosphofructokinase and its properties under simulating In Vivo conditions. J. Biosci. 6, 643-653, (1984).
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