CLASSIFICATION AND NOMENCLATURE OF DNA VIRUSES

This presentation talks about the classification and nomenclature of DNA viruses.

1. Classification and Nomenclature of DNA viruses A.SAMUEL STEVE BSc.MEDICAL MICROBIOLOGY AND APPLIED MOLECULAR BIOLOGY ThePhoto by PhotoAuthor is licensed under CCYYSA.

2. INDICATION   This Photo by Unknown Author is licensed under CC BY-NC

3. VIRUS A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. A virus is  an infectious microbe consisting of a segment of nucleic acid (either DNA or RNA) surrounded by a protein coat . ThePhoto by PhotoAuthor is licensed under CCYYSA. ThePhoto by PhotoAuthor is licensed under CCYYSA.

4. CLASSIFICATION ~Viruses are classified into two main divisions depending on the type of nucleic acid they possess: riboviruses are those containing RNA and deoxyriboviruses are those containing DNA. ~Further classification is based on other properties such as the strandedness of nucleic acid, symmetry of the nucleocapsid, presence of an envelope, size and shape of the virion and the number of capsomers. VIRUSES DNA VIRUSES RNA VIRUSES

5. CLASSIFICATION

6. DNA VIRUSES DNA viruses are viruses that have a DNA genome and use either host or virally encoded DNA polymerases to replicate themselves. They can have a wide range of genome sizes and typically have a gene expression pattern with early and late phases.  Dna virus Strand state Poxviridae Double stranded Herpesviridae Double stranded Adenoviridae Double stranded Papovaviridae Double stranded Parvoviridae Single stranded Hepadnaviridae Double stranded

7. Poxviridae family The Poxvirus family is named after the word "pox", which means a blister, pustule, or eruptive sore. The name comes from the original grouping of viruses that caused diseases that produced poxes on the skin. These are large, brick-shaped or ovoid viruses (300 x 240 x 100 nm), with complex structure, having a lipid containing an outer coat, one or two lateral bodies and a core carrying a single linear molecule of double-stranded DNA. Multiplication and maturation take place in the cytoplasm. The family is divided into several genera .

8. Herpesviridae family The name "herpes" comes from the Greek word herpein , which means "to creep". The term dates back to early Greek civilization, about 2,000 years ago, and refers to the way herpetic skin lesions spread. These lesions often involve blisters and can be seen in flares of herpes simplex 1, herpes simplex 2, and herpes zoster (shingles). These are medium-sized viruses containing linear double-stranded DNA. The icosahedral nucleocapsid (100 nm) has 162 capsomers and is surrounded by a lipid-containing envelope. Multiplication takes place in the nucleus and maturation by budding through the nuclear membrane. Only one genus, Herpesvirus, has been characterised , but several members of the family await classification.

9. Adenoviridae family Adenoviruses are named after the human adenoids, where they were first isolated in 1953. The viruses were isolated from cell cultures derived from adenoid tissue, which often degraded over time . These are medium-sized (70-90 nm) non-enveloped, icosahedral viruses with 252 capsomers. Members have been classified into two genera: Mastadenovirus (mammalian adenoviruses) and Aviadenovirus (adenoviruses of birds).

10. Papovaviridae family The acronym " papova " is  made up of the first two letters of "human papillomavirus," "mouse polyomavirus," and "simian vacuolating virus“. T hese are small (40-55 nm) non-enveloped, double-stranded DNA viruses with 72 capsomers. Two genera have been identified : Papillomavirus and Polyomavirus.

11. Parvoviridae family The name parvovirus comes from the Latin word parvum, which means "small" or "tiny". Parvoviruses are among the smallest viruses known, with a diameter of 18–28 nanometers. These are very small (18- 26 nm) non-enveloped viruses with 31 capsomers. The genome consists of single-stranded DNA. Three genera have been described: Parvovirus, Adenosatellovirus and Densovirus .

12. Hepadnaviridae family Hepadnaviruses , as their " hepa " name implies,  infect liver cells and cause hepatitis. This is true not only of the human pathogen Hepatitis B Virus but also the hepadnaviruses that infect other organisms . This consists of the human hepatitis type B virus and related viruses of animals and birds. (The name comes from hepa = liver, and dna for DNA core.) The virion is spherical, 42 nm in diameter, consisting of a 27-nm core surrounded by an envelope having virus-specific antigens.

13. SUMMARIZATION NAME OF THE VIRUS FAMILY DERIVATION OF FAMILY`S NAME NUCLEIC ACID PRESENT , STRAND STATE ENVELOPE STATUS SIZE OF THE VIRUS\DIAMETER SHAPE OF THE VIRUS Poxviridae Pox = blister , papule or eruptive sore. DNA,double stranded +\- 200-300 nm BRICK Herpesviridae Herpes = to creep DNA,double stranded Non-enveloped 100-110 nm ICOSAHEDRAL Adenoviridae Adeno = derived from human adenoids DNA,double stranded Non-enveloped 90-100 nm SPHERICAL Papovaviridae Papova = PA-Papilloma PO-Polyoma VA-Vacuolating DNA,double stranded Non-enveloped 45-55 nm ICOSAHEDRAL Parvoviridae Parvo = small or tiny DNA,single stranded Non-enveloped 18-26 nm ICOSAHEDRAL Hepadnaviridae Hepa = infects liver cells DNA,double stranded Enveloped 42-50 nm SPHERICAL

14. Bibiliography ~ Ananthanarayan & Paniker’s Textbook of Microbiology 10 ~ https:\\www.sciencedirect.com ~ https:\\www.google.co.in ~ https:\\www.microbenotes.com ~ https://pubmed.ncbi.nlm.nih.gov