Vicky van Santen
phone: 334-844-2668email: vanvick@vetmed.auburn.edu
Dr. Vicky van Santen has been a faculty member in the Department
of Pathobiology since 1988. She earned her Ph.D. degree from the University
of Chicago in 1982. Her dissertation research dealt with characterization
of Epstein-Barr virus mRNAs expressed in latently- infected Epstein-Barr
virus-transformed cells. During her post-doctoral training in the Laboratory
of Genetics at the University of Wisconsin-Madison, she investigated the
mechanism of higher eucaryotic pre-mRNA splicing.
Research Interests
My research interests include two very different viruses: bovine herpesvirus 4 (BHV-4) and chicken anemia virus (CAV). BHV-4 has been isolated from cattle with a wide variety of disorders as well as from apparently healthy cattle; its relationship with disease is unclear. BHV-4 is genetically related to Epstein-Barr virus (EBV) and Kaposi's Sarcoma-associated herpesvirus (KSHV) of humans, but whether it has biological properties similar to these human viruses is unknown. My research on BHV-4 focuses on the structure and function of immediate early (IE) genes and on development of in vitro model systems for persistent and latent infection.We have identified and characterized the IE genes of BHV-4 by characterizing the IE RNAs by Northern blot analysis, S1 nuclease mapping, cDNA cloning, primer extension analysis, and nucleotide sequence analysis. BHV-4 encodes two IE RNAs, IE1 and IE2. The nucleotide sequence of the IE1 gene predicts an amino acid sequence with homology to two genes found in KSHV. The nucleotide sequence of the IE2 gene predicts an amino acid sequence with homology to an EBV transactivator, R, which transactivates expression of EBV E genes. To determine whether BHV-4 IE1 and IE2 are transactivators of BHV-4 E and L genes, we linked the promoter regulatory regions upstream of BHV-4 E genes to a reporter gene, chloramphenicol acetyl transferase (CAT), and introduced them into cells along with a plasmid encoding IE1 or IE2. Comparing the amount of CAT produced in the presence and absence of IE1 and IE2 showed that IE2 transactivates all BHV-4 E and L promoters tested. IE1 does not transactivate these BHV-4 promoters, and does not augment IE2 transactivation. Like the EBV R transactivator, BHV-4 IE2 is a sequence-specific DNA binding protein, as demonstrated by gel retardation assays. To define the BHV-4 IE2 recognition site, we have created deletions in the BHV-4 E and L promoters and determined which sequences are sufficient for binding and transactivation by IE2.
Like other herpesviruses, BHV-4 establishes persistent infections in its natural host. In collaboration with Dr. Gaetano Donofrio of the College of Veterinary Medicine, University of Parma, Italy, we have established cell lines persistently-infected with BHV-4 using wt or recombinant virus carrying a selectable marker. These cell lines contain circular episomal viral DNA and produce a small amount of virus, but continue to grow. We have also constructed a recombinant BHV-4 expressing the green fluorescent protein and used it to show that BHV-4 can infect a wide variety of cell types from different species without causing cytopathic effect. These results suggest that BHV-4 might be useful as a gene delivery vector.
CAV infection causes anemia in very young chickens and transient immunosuppression
in other chickens. The small, circular, single-stranded DNA genome
exhibits extremely limited variability. We have characterized CAV
genomes directly from infected tissues of chickens submitted to the Alabama
Veterinary Diagnostic Laboratory and confirmed this lack of variability.
Future studies will focus on the immune response of chickens to CAV.
Selected Publications
van Santen, V. L. (1991). Characterization of the bovine herpesvirus 4 major immediate-early transcript. Journal of Virology 65, 5211-5224.
van Santen, V. L., and Chang, L. Y. (1992). Cloning and mapping of EcoRI, HindIII, and PstI fragments of bovine herpesvirus 4 (DN-599) genome. Intervirology 34, 44-52.
Chang, L. Y., and van Santen, V. L. (1992). Immediate-early, early, and late RNAs in bovine herpesvirus-4-infected cells. Virology 191, 909-920.
van Santen, V. L. (1993). Characterization of a bovine herpesvirus 4 immediate-early RNA encoding a homolog of the Epstein-Barr virus R transactivator. Journal of Virology 67, 773-784.
Galik, P. K., van Santen, V. L., Stringfellow, D. A., Bird, R. C., Wright, J. C., and Smith, P. C. (1993). Development of a DNA probe for identification of bovine herpesvirus 4. American Journal of Veterinary Research 54, 653-659.
Lauerman, L. H., Hoerr, F. J., Sharpton, A. R., Shah, S. M., and van Santen, V. L. (1993). Development and application of a polymerase chain reaction assay for Mycoplasma synoviae. Avian Diseases 37, 829-834.
Silverstein, P. S., Bird, R. C., van Santen, V. L., and Nusbaum, K. E. (1995). Immediate-early transcription from the channel catfish virus genome: characterization of two immediate-early transcripts. Journal of Virology 69, 3161-3166.
Zhang, L., and van Santen, V. L. (1995). Interaction of bovine herpesvirus 4 (BHV-4) immediate early 2 gene product with BHV-4 thymidine kinase promoter-regulatory region. Journal of General Virology 76, 2433-2445.
Lomonte, P., Bublot, M., van Santen, V., Keil, G. M., Pastoret, P. P., and Thiry, E. (1995). Analysis of bovine herpesvirus 4 genomic regions located outside the conserved gammaherpesvirus gene blocks. Journal of General Virology 76, 1835-1841.
Lomonte, P., Bublot, M., van Santen, V., Keil, G., Pastoret, P. P., and Thiry, E. (1996). Bovine herpesvirus 4: genomic organization and relationship with two other gammaherpesviruses, Epstein-Barr virus and herpesvirus saimiri. Veterinary Microbiology 53, 79-89.
Bermudez-Cruz, R., Zhang, L., and van Santen, V. L. (1997). Characterization of an abundant, unique 1.7-kilobase bovine herpesvirus 4 (BHV-4) late RNA and mapping of a BHV-4 IE2 transactivator-binding site in its promoter-regulatory region. Journal of Virology 71, 527-538.
Silverstein, P. S., van Santen, V. L., Nusbaum, K. E., and Bird, R. C. (1998). Expression kinetics and mapping of the thymidine kinase transcript and an immediate-early transcript from channel catfish virus. Journal of Virology 72, 3900-3906.
Bermudez-Cruz, R., Zhang, L., and van Santen, V. L. (1998). Characterization of a bovine herpesvirus 4 (BHV-4) 1.1 kb RNA and its transactivation by BHV-4 immediate-early 2 gene product. Archives of Virology 143, 2391-2412.
Donofrio, G., Cavirani, S., and van Santen, V. L. (2000). Establishment of a cell line persistently infected with bovine herpesvirus-4 by use of a recombinant virus. Journal of General Virology 81 , 1807-1814.
Ruffin, D. C., van Santen, V. L., Zhang, Y., Voelker, L., Panangala, V. S., and Dybvig, K. (2000). Transposon mutagenesis of Mycoplasma gallisepticum by conjugation with Enterococcus faecalis and determination of insertion site by direct genomic sequencing. Plasmid 44, 191-195.
Donofrio, G., and van Santen, V. L. (2001). A bovine macrophage cell line supports BHV-4 persistent infection. Journal of General Virology 82, 1181-1185.
van Santen, V. L., Li, L., Hoerr, F. J., and Lauerman, L. H. (2001). Genetic characterization of chicken anemia virus from commercial broiler chickens in Alabama. Avian Diseases 45, 373-388.
Donofrio, G., Cavirani, S., Simone, T., and van Santen, V. L. (2002) Potential of bovine herpesvirus 4 as a gene delivery vector. Journal of Virological Methods 101, 49-61.
Donofrio, G., Galli, C., Lazzari, G., van Santen, V.L., Cavirani, S., and Flammini, C.F. (2003) Interaction of a green recombinant bovine herpesvirus 4 with in vitro-produced bovine embryos. Veterinary Research Communications 27, 415-424.
van Santen, V. L., Kaltenboeck, B., Joiner, K. S., Macklin, K. S., and Norton, R. A. (2004) Real-time quantitative PCR-based serum neutralization test for detection and titration of neutralizing antibodies to chicken anemia virus. Journal of Virological Methods 115, 123-135.
van Santen, V. L., Hoerr, F. J., Joiner, K. S., Murray, C., Petrenko, N., and Toro, H. (2004) Pathogenesis of chicken anemia virus: comparison of the oral and the intramuscular routes of infection. Avian Diseases 48, 494-504.
