Concept of virology and oncology_Introduction.pptx

Concept of virology and oncology_Introduction

1. Presentation on chapter 1,2 & 3 MS- 01,02,05

2. ● It is the branch of microbiology. Virology Concept Virology Virus characteristics Classification of virus Relationship with host Discover the treatment for viral disease Pharmaceutical use

3. History Endemic by smallpox Variolation for prevention Vaccination

4. ●Firstly Immunization technique for an individual against smallpox ( variola ). ●Completed by inserting powdered smallpox scabs or fluid from pustules into superficial scratches mate in skin. ●For this, pustules can be developed but less severe. ●Here, a immune system is developed for recognizing and destroy the virus. ●It make the body tiny and sick in order to guard against major future infections . Variolation

5. N atural smallpox or variolation failed to protect from a second attack For this, Edward jenner first developed smallpox vaccine. This vaccine can be derived from cowpox, distinct from smallpox. The modern smallpox vaccination kills about 1 or 2 in a million people. By vaccination one cannot get smallpox from the vaccine. It contains no smallpox virus . Vaccination

6. In medical terms, a booster dose is an extra administration of a vaccine after an earlier (prime) dose. After initial immunization, a booster injection or booster dose is a re-exposure to the immunizing antigen. ... The need for a booster dose following a primary vaccination is evaluated in several ways. Vaccine and Booster

7. Here, extracelluer form of virus is called virion. Virion Existence of virus Extracellular Intracellular

8. Virion Structure

9. The viral nucleic acid genome Present in the center of the virion Control the viral heredity and variation R esponsible for the infectivity. Viral core Based on nucleic acid DNA virus RNA virus

10. The protein shell, or coat, that encloses the nucleic acid genome. Protect the viral nucleic acid. Participate in the viral infection. Share the antigenicity Capsomere is the subunit of the capsid Capsomere is the smallest morphological unit visible with an electron microscope. Viral capsid

11. The core of a virus particle consisting of the genome plus a complex of proteins. C omplex of proteins = Structural proteins +Non- Structural proteins (Enzymes &Nucleic acid binding proteins) Neucleocapsid Symmetry of nucleocapsid Helical Cubic Complex

12. Nomenclature and Classification of Plant and Animal Viruses

13. Various approaches, (do not obey the binomial nomenclature) derived from: 1. Named after the diseases eg . Measles virus, smallpox virus 2. Name after the places where the disease first reported eg . Newcastle disease virus, Ebola virus, Norwalk virus , Bunyaviridae 3. Host and signs of disease eg . Tobacco mosaic virus, cauliflower mosaic virus brome mosaic virus Nomenclature of Plant and Animal VIruses

14. 4. Latin and Greek words eg . Coronaviridae – “crown” Parvoviridae – “small” 5. Virus discovers eg. Epstein-Barr virus 6. How they were originally thought to be contracted eg . dengue virus (“ evil spirit”), influenza virus ( the “influence” of bad air ) 7. Combinations of the above eg . Rous Sarcoma virus CONTINUED

15. Virus classification is the process of naming viruses and placing them into a taxonomic system. Viruses are mainly classified by phenotypic characteristics, such as morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause . Currently there are two main schemes used for the classification of viruses: 1 . The International Committee on Taxonomy of Viruses (ICTV ) system and 2 . Baltimore classification system, Classification of Plant and Animal Viruses

16. In July 2013, the ICTV definition of species changed to state: "A species is a monophyletic group of viruses whose properties can be distinguished from those of other species by multiple criteria.“ Viral classification starts at the level of order and continues as follows, with the taxon suffixes given in italics: Order (- virales ) Family (- viridae ) Subfamily (- virinae ) Genus (-virus) Species International Committee on Taxonomy of Viruses ( ICTV)

17. Baltimore classification (first defined in 1971) is a classification system that places viruses into one of seven groups depending on a combination of their nucleic acid (DNA or RNA ), strandedness (single-stranded or double-stranded ), Sense (+ or -), and method of replication . Named after David Baltimore, a Nobel Prize-winning biologist, these groups are designated by Roman numerals BALTIMORE CLASSIFICATION

18. 7 class of Baltimore classification

19. Class I Double-stranded (ds) DNA viruses are in class 1 The production of mRNA and genome replication in such viruses occurs as it would from the host genome. Class II Single-stranded( ss ) DNA viruses. These viruses form a double stranded DNA intermediate during replication and this intermediate used for transcription. • RNA polymerase requires double-stranded DNA as template. CONTINUED

20. Positive and Negative strand RNA viruses The production of mRNA and genome replication is much different with RNA viruses (Class III-VI). mRNA is the complementary base sequence to the template strand of DNA. • In virology, mRNA is said to be plus(+) configuration. While its complement is said to be the minus (-) configuration. CONTINUED

21. How does these viruses replicate ? Cellular RNA polymerases do not catalyze formation of RNA from an RNA template but from DNA template. RNA viruses whether plus, negative or double stranded require a specific RNA- dependant RNA polymerase. CONTINUED

22. Class IV Positive-strand of RNA viruses . Viral genome is of the plus configuration and hence serve directly as mRNA. The viruses required other protein, therefore mRNA encodes a virus specific and RNA dependent RNA polymerase. Once synthesized, this polymerase makes complementary minus strands of RNA and then use as template to make more plus strand. CONTINUED

23. Class III and Class V Class III (double-stranded RNA viruses) Class V(negative strand RNA virus) mRNA must be first synthesized, however cells does not have RNA polymerase. To circumvent ,these viruses contain enzyme in the virion,enters cell along with the genomic RNA. Therefore , in this case complementary plus strand is synthesized by RNA dependant RNA polymerase and used as mRNA. Plus strand used as template to make more negativestrand genome CONTINUED

24. Class VI Single-stranded RNA genome that replicates with DNA intermediate. This RNA virus require reverse transcriptase to copy the information found in RNA to DNA . Class VII Double-stranded DNA genome that replicates with RNA intermediate. Required reverse transcriptase Mechanism producing mRNA is similar in virus Class I CONTINUED

25. Virus quantification  involves counting the number of viruses in a specific volume to determine the virus concentration . 2 types: Traditional methods Modern methods Q uantification

26. Plaque assay : C onfluent monolayer of host cells is infected with the virus at varying dilutions and covered with a semi-solid medium, such as agar or  carboxymethyl cellulose, to prevent the virus infection from spreading indiscriminately. Traditional methods

27. In general, these methods quantify either the amount of all protein or the amount of a specific virus protein in the sample rather than the number of infected cells or virus particles. Protein assay

28. The hemagglutination assay (HA) is a common non-fluorescence protein quantification assay specific for  influenza. Hemagglutination assay (HA)

29. Flow cytometry : A virus counter quantifies the number of intact virus particles in a sample using fluorescence to detect colonalized proteins and nucleic acids. Modern methods

30. Method that allows high-throughput single particle measurements of individual virus particles, as they are driven through a size-tunable  nanopore, one at a time. Tunable resistive pulse sensing (TRPS)

31. Utilizes  polymerase chain reaction chemistry to amplify viral DNA or RNA to produce high enough concentrations for detection and quantification by fluorescence . Quantitative PCR

32. Is a more modern variation of a protein assay that utilizes a specific antibody linked to an enzyme to detect the presence of an unknown amount of antigen (i.e. virus) in a sample. Enzyme-linked immunosorbent assay (ELISA)