Retroviruses are a family of RNA viruses that replicate through a unique reverse transcription process, converting their RNA genomes into DNA within the host cell. Key Retroviral Proteins play critical roles in this replication cycle. The major structural proteins include the capsid (CA), nucleocapsid (NC), and envelope (Env) proteins. The capsid protein forms the viral core, protecting the viral RNA, while the nucleocapsid protein aids in RNA packaging and reverse transcription. The envelope protein, comprised of surface (SU) and transmembrane (TM) subunits, facilitates viral entry into host cells. The replication process begins with the binding of the retroviral envelope protein to specific host cell receptors, followed by fusion and entry. Once inside the host cell, the viral RNA genome is reverse transcribed into DNA by the reverse transcriptase (RT) enzyme, forming a double-stranded DNA copy known as the provirus. The provirus integrates into the host cell genome with the help of the integrase (IN) protein. The integrated provirus serves as a template for transcription and translation of viral proteins, ultimately leading to the production of new virions.