21.1 Viral Evolution, Morphology, and Classification
Discovery and Detection
Viruses are infectious particles about 100 times smaller than bacteria and can only be observed by electron microscopy.
Evolution of Viruses
The evolution of viruses is speculative as they do not fossilize; biochemical and genetic information is used to create virus histories.
Viruses of all shapes and sizes consist of a nucleic acid core, an outer protein coating or capsid, and sometimes an outer envelope.
Viruses are classified by factors such as their core content, capsid structure, presence of outer envelope, and how mRNA is produced.
21.2 Virus Infections and Hosts
Steps of Virus Infections
Viral infection involves the incorporation of viral DNA into a host cell, replication of that material, and the release of the new viruses.
Different Hosts and Their Viruses and Introduction to Bac...
Viruses are host specific and reproduce by either infecting and remaining within the host cell or by using the cell to create more viruses.
Animal viruses have their genetic material copied by a host cell after which they are released into the environment to cause disease.
Plant viruses can cause damage to stems, leaves, and fruits and can have a major impact on the economy because of food supply disruptions.
21.3 Prevention and Treatment of Viral Infections
Vaccines for Prevention
Vaccinations prevent viruses from spreading by building immunity to the virus.
Vaccines and Anti-viral Drugs for Treatment
Vaccines and anti-viral drugs can be used to inhibit the virus and reduce symptoms in individuals suffering from viral infections.