In general, DNA viruses replicate mainly in the nucleus and RNA viruses mainly in the cytoplasm, but there are exceptions, eg. Pox viruses contain DNA but replicate in the cytoplasm of the host cell. Release Release of new infectious virions is the final stage of replication. This may occur by by budding from the cell surface, as occurs with many enveloped viruses. In this case capsid proteins and nucleic acid condense directly adjacent to the cell membrane and viral-coded envelope proteins, introduced into the cell membrane, concentrate in the vicinity of capsid aggregates.
Some viruses utilize the cellular secretory pathway to exit the cell.
Virus particles enclosed within Golgi -derived vesicles are released to the outside of the cell when the transport vesicle fuses with the cell membrane. Disintegration or lysis of the infected cell can also result in the release of intact infectious virions. Viruses can be studied in a number of direct and indirect ways and all these methods can be applied in a diagnostic situation , ie. The structure of different viruses has been elucidated by a range of electron microscopy and x-ray crystallography techniques. Viral antigens can be detected by a wide range of serological techniques utilising polyclonal or monoclonal antibodies.