Systematic Veterinary Virology

REPLICATION

• Since herpesviruses have DNA as genome, they replicate in the nucleus. The virions attaches to host cell with the envelope glycoprotein, The virus enters into the cell through fusion of viral envelope with plasma membrane of host cell.
• The capsid travels along the cytoskeleton to a nuclear pore where the viral DNA is released. The linear genome enters the nucleus and circularises. Once in the nucleus, the viral DNA is transcribed into mRNA by cellular RNA polymerase II. After transcription in the nucleus, all mRNA transcripts are translated into protein in the cytoplasm.
• Subsequently, the proteins go to the nucleus, stay in the cytoplasm, or become a part of the membrane bilayer. Capsid proteins assemble in the nucleus to form empty capsids and full-length viral DNA is packaged to form nucleocapsids. The nucleocapsids associate with segments of the nuclear membrane where tegument and glycosylated envelope proteins have bound.
• This association triggers envelopement by budding through the nuclear membrane. Enveloped virions accumulate in the endoplasmic reticulum (ER). Mature virions are released by exocytosis