What are CD4 lymphocytes? What is the relationship between these cells and HIV? How does HIV replicate?

CD4 lymphocytes are T helper lymphocytes that there in their plasma membrane receptor proteins known as CD4.

CD4 lymphocytes are the cells that HIV infects and within which the virus replicates. HIV has proteins in its capsule that bind to the CD4 receptors of lymphocytes. By that bond the virus fuses with the cell membrane and its content (RNA, protease, reverse transcriptase, etc.) penetrates into the cytoplasm and the viral replication process begins.

HIV RNA is then changed into DNA by the reverse transcriptase. The new DNA is inserted into the genetic material of the lymphocyte with the aid of enzymes known as integrases. By transcription and translation this DNA commands the synthesis of proteins essential for the assemblage of new viruses. Long polypeptides are therefore produced and then fragmented into proteins and viral enzymes by the enzyme protease. So new HIV viruses are assembled and break the cell membrane to gain the circulation.