Basic Principles of Virology are discussed here.If You want to study viruses,you must understand first its principles.
- The field of virology encompasses viral discovery, the study of virus structure and reproduction, and the importance of viruses in biology and disease.
- While this text focuses primarily on viruses that infect vertebrates, especially humans, it is important to keep in mind that viruses infect all living things including insects, plants, bacteria, and even other viruses
- . Viruses are not solely pathogenic nuisances; they can be beneficial. Viruses contribute to ecological homeostasis, keep our immune responses activated and alert, and can be used as molecular flashlights to illuminate cellular processes.
- Viruses have been part of all of human history: they were present long before Homo sapiens evolved, and the majority of human infections were likely acquired from other animals (zoonoses). As viruses continue to be discovered, our understanding of how human health and well-being are affected by these agents remains incomplete.
- Viruses are obligate intracellular parasites and depend on their host cell for all aspects of the viral life cycle.
- While Koch’s postulates were essential for defining many agents of disease, not all pathogenic viruses fulfilled these criteria.
- Viruses can be cataloged based on their appearance, the hosts they infect, or the nature of their nucleic acid genome. The Baltimore classification allows relationships among various viral genomes and the pathway to mRNA to be determined.
- A common strategy underlies the propagation of all viruses. This textbook describes that strategy and the similarities and differences in the manner in which it is accomplished by different viruses.
Viruses are the most abundant entities in the biosphere. The biomass on our planet of bacterial viruses alone exceeds that of all of Earth’s elephants by more than 1,000-fold. There are more than 1030 bacteriophage particles in the world’s oceans, enough to extend out into space for 200 million light-years if arranged head to tail.Whales are commonly infected with a member of the virus family Caliciviridae that causes rashes, blisters, intestinal problems, and diarrhea and can also infect humans. Infected whales excrete more than 1013 calicivirus particles daily. • The average human body contains approximately 1013 cells, but these are outnumbered 10-fold by bacteria and as much as 100-fold by virus particles. • With about 1016 human immunodeficiency virus (HIV) genomes on the planet today, it is highly probable that somewhere there exist HIV genomes that are resistant to every one of the antiviral drugs that we have now or are likely to have in the future.