Background and a significant of the study 1.3. Purposes of the study 1.4. Scope of the study 1.5. Expected outcomes PART II THE MANUSCRIPTS OF DISSERTATION CHAPTER I miR-21 promotes dengue virus serotype 2 replication in HepG2 cells Abstract 1.1. Introduction 1.2. Materials and Methods 1.2.1. Cells and culture conditions 1.2.2. Viruses 1.2.3. Oligonucleotides 1.2.4. miR expression profile during DENV replication 1.2.5. Nucleic acid binding properties of PNA-21 1.2.6. Repression of miR-21 expression by AMO-21 1.2.7. Expression of MYD88 and IRAK1 transcripts after miR-21 repression 1.2.8. Influence of AMO-21 on DENV 2 replication 1.2.9. Fluorescent microscopy 1.2.10. Statistical analysis vii PAGE 1.3. Results 1.3.1. Regulation of miRNAs in DENV 2 infected HepG2 cells 1.3.2. Specificity of miR-21 up-regulation by DENV 2 1.3.3. miR-21 promotes DENV 2 replication 1.3.4. Transfection of AMO-21, PNA-21, and AMO-21/PNA-21 in HepG2 1.3.5. Specific inhibition of AMO-21 by PNA-21 in the DENV 2 infected HepG2 cell 1.4. Discussion CHAPTER II Modulation of bovine herpesvirus-1 infection by virally encoded microRNAs