Human Respiratory Syncytial Virus is a negatively stranded, enveloped RNA virus and belongs to the Orthopneumovirus genus of the Pneumoviridae family. It is divided into two antigenic groups (subgroups) hRSV A and hRSV B] The genome is 15 kb long with 10 gene transcripts encoding 11 proteins of which the G glycoprotein and the fusion (F) glycoprotein are major surface proteins that function in attachment. Antigenic groups can be further divided into 16 RSV-A and 22 RSV-B genotypes based on the sequence variability of the second hypervariable region (HVR2) of the distal third region of the G gene.