Dr. Long is an Adjunct Faculty member in the Baccalaureate Biology Program at St. Petersburg College. He holds a Ph.D. in Biochemistry from Brandeis University. Dr. Long brings experience spanning academic research, biotechnology, molecular diagnostics, and STEM education. Prior to joining St. Petersburg College, he served as a Research Scientist at the Frederick National Laboratory for Cancer Research, where he led the development of advanced molecular and genomic assays supporting HIV and SIV research programs. He also held scientific positions at QIAGEN and Immunologix Laboratories, contributing to the development of molecular diagnostic technologies, digital PCR applications, cancer mutation profiling tools, and genomic analysis platforms.

Throughout his career, Dr. Long has contributed extensively to the scientific literature through peer-reviewed publications and has served as a reviewer for journals in molecular biology, virology, cell biology, and biomedical research. He was also the guest editor of a special issue of Methods focused on digital PCR technologies and infectious disease applications.

As an educator, Dr. Long has taught and mentored students at multiple levels, including university, graduate, high school, and professional settings. His teaching philosophy emphasizes scientific inquiry, critical thinking, and the integration of foundational biological concepts with contemporary advances in biomedical research. He is committed to helping students develop both conceptual understanding and practical laboratory skills that prepare them for careers in science, healthcare, biotechnology, and research.

Dr. Long's research integrates molecular virology, cell signaling, and genomic technologies to better understand the mechanisms that govern viral replication, persistence, and host responses to infection. His interests include HIV and emerging RNA viruses, viral latency and reservoir biology, host regulatory pathways, RNA biology, and the development of highly sensitive molecular diagnostics. He is also interested in the application of advanced genomic and liquid biopsy technologies to infectious diseases and cancer.

Selected publications:
(*Corresponding author)

Long, S.* Digital PCR: Methods and Applications in Infectious Diseases. Methods. 2022;201:1–4. DOI: 10.1016/j.ymeth.2022.02.008

Long, S.* In pursuit of sensitivity: Lessons learned from viral nucleic acid detection and quantification on the Raindance ddPCR platform. Methods. 2022;201:82–95. DOI: 10.1016/j.ymeth.2021.04.008

Long, S.*, Berkemeier, B. Ultrasensitive detection and quantification of viral nucleic acids with Raindance droplet digital PCR (ddPCR). Methods. 2022;201:49–64. DOI: 10.1016/j.ymeth.2021.04.025

Long, S.* SARS-CoV-2 subgenomic RNAs: Characterization, utility, and perspectives. Viruses. 2021;13(10):1923. DOI: 10.3390/v13101923

Long, S.*, Berkemeier, B. Development of a reverse transcription droplet digital PCR (RT-ddPCR) assay for sensitive detection of simian immunodeficiency virus (SIV). Virology Journal. 2021;18:35. DOI: 10.1186/s12985-021-01506-0

Long, S.*, Berkemeier, B. Development and optimization of a simian immunodeficiency virus (SIV) droplet digital PCR (ddPCR) assay. PLoS One. 2020;15(10):e0240447. DOI: 10.1371/journal.pone.0240447

Long, S.*, Berkemeier, B. Maximizing viral detection with SIV droplet digital PCR (ddPCR) assays. PLoS One. 2020;15(5):e0233085. DOI: 10.1371/journal.pone.0233085

Long, S., Fennessey, C.M., Newman, L., et al. Evaluating the intactness of persistent viral genomes in SIV-infected rhesus macaques initiating antiretroviral therapy within one year of infection. Journal of Virology. 2019;94(1):e01308-19. DOI: 10.1128/JVI.01308-19

Brait, M., Izumchenko, E., Kagohara, L.T., Long, S., et al. Comparative mutational landscape analysis of patient-derived tumour xenografts. British Journal of Cancer. 2017;116:515–523. DOI: 10.1038/bjc.2016.457

Calascibetta, F., Micci, L., Carnathan, D., Lawson, B., Vanderford, T., Bosinger, S., Chahroudi, A., Mackel, J., Keele, B., Long, S., Lifson, J., Paiardini, M., Silvestri, G. Antiretroviral therapy in SIV-infected sooty mangabeys: implications for AIDS pathogenesis. Journal of Virology. 2016;90(16):7541–7551. DOI: 10.1128/JVI.00843-16

Long, S., You, M., Wang, L., Jiang, X., Cheng, J., Wang, Y. Pathway-focused cancer mutation profiling with somatic mutation PCR arrays. Cancer Research. 2011;71(8 Suppl):4863. DOI: 10.1158/1538-7445.AM2011-4863

Avruch, J., Long, X., Lin, Y., Ortiz-Vega, S., Rapley, J., Oshiro, N. Regulation of TOR Complex 1 by amino acids through small GTPases. The Enzymes (Elsevier). 2010;27:115–151. DOI: 10.1016/S1874-6047(10)27007-8

Avruch, J., Long, X., Lin, Y., Ortiz-Vega, S., Rapley, J., Papageorgiou, A., Oshiro, N., Kikkawa, U. Activation of mTORC1 in two steps. Biochemical Society Transactions. 2009;37:223–226. DOI: 10.1042/BST0370223

Avruch, J., Long, X., Ortiz-Vega, S., Rapley, J., Dai, N. Amino acid regulation of TOR complex 1. American Journal of Physiology-Endocrinology and Metabolism. 2009;296:E592–E602. DOI: 10.1152/ajpendo.90940.2008

Long, X., Lin, Y., Ortiz-Vega, S., Busch, S., Avruch, J. The Rheb switch 2 segment is critical for signaling to TOR complex 1. Journal of Biological Chemistry. 2007;282:18542–18551. DOI: 10.1074/jbc.M702027200

Long, X., Ortiz-Vega, S., Lin, Y., Avruch, J. Rheb binding to mTOR is regulated by amino acid sufficiency. Journal of Biological Chemistry. 2005;280:23433–23436. DOI: 10.1074/jbc.C500169200

Avruch, J., Hara, K., Lin, Y., Liu, M., Long, X., Ortiz-Vega, S., Yonezawa, K. Insulin and amino acid regulation of mTOR signaling. Oncogene. 2006;25:6361–6372. DOI: 10.1038/sj.onc.1209884

Long, X., Lin, Y., Ortiz-Vega, S., Yonezawa, K., Avruch, J. Rheb binds and regulates mTOR kinase. Current Biology. 2005;15:702–713. DOI: 10.1016/j.cub.2005.02.053

Avruch, J., Lin, Y., Long, X., Murthy, S., Ortiz-Vega, S. Regulation of TOR pathway by insulin and nutrients. Current Opinion in Clinical Nutrition and Metabolic Care. 2005;8:67–72. DOI: 10.1097/00075197-200501000-00010

Long, X., Müller, F., Avruch, J. TOR action in mammalian cells and C. elegans. In: TOR: Target of Rapamycin. Springer. 2004:115–138. DOI: 10.1007/978-3-642-18930-2_7

Long, X., Spycher, C., Han, Z.S., Rose, A.M., Müller, F., Avruch, J. TOR deficiency in C. elegans causes developmental arrest. Current Biology. 2002;12:1448–1461. DOI: 10.1016/S0960-9822(02)01091-6

Hara, K., Maruki, Y., Long, X., et al. Raptor mediates TOR action. Cell. 2002;110:177–189. DOI: 10.1016/S0092-8674(02)00833-4

Long, X., Griffith, L. SUMO-1 conjugation system modifies neuronal CaMKII. Journal of Biological Chemistry. 2000;275:40765–40776. DOI: 10.1074/jbc.M005708200