New viruses are released by budding off the host cell's plasma membrane, turning the host cell for a time into a viral factory. Retroviruses Retroviruses have RNA and the enzyme reverse transcriptase instead of DNA as their nucleic acid core. This new DNA is incorporated into the host DNA, where it transcribes new viral RNA genomes, as well as the RNA to synthesize new reverse transcriptase and protein capsules. Viral diseases include the flu, common cold, herpes, measles, chicken pox, small pox, and encephalitis. Antibiotics are not effective against viruses.
Vaccination offers protection for uninfected individuals.
Emergent Viruses Viruses are usually quite specific as to their hosts and even to the types of cells they infect in a multicellular host. The discovery of viroids, nucleic acid without a protein capsule and prions, infectious proteins, subtracts another level of complexity. Both viroids and prions can cause diseases. Very interesting site with new features each month. Of note here are sections dealing with viral life cycles.