RNA-Seq is a recently developed approach to transcriptome profiling that uses deep-sequencing technologies. The availability of RNA-seq data encouraged computational biologists to develop algorithms to process the data in a statistically disciplinary manner to generate biologically meaningful results. Clustering viral sequences allows us to characterize the composition and structure of intrahost and interhost viral populations, which play a crucial role in disease progression and epidemic spread. In this research, we propose and validate a new entropy-based method for clustering aligned viral sequences considered as categorical data. The method finds a homogeneous clustering by minimizing information entropy rather than the distance between sequences in the same cluster. Moreover in this research, we present a novel pathway analysis method based on Expectation-Maximization (EM) algorithm to study the enzyme expression and pathway activity using meta-transcriptomic data. We will also discuss our approaches to generating unique gene signatures to understand the role of sensory nerve interference in the anti-melanoma immune response and study the racial disparity in Triple-negative breast cancer. Finally, we present our method to detect the retained introns in RNA-seq data to develop a vaccine against cancer having p53 mutations. In summary, this research provides novel approaches to exploring RNA-seq data and their application to real-world biological research.