rna virus slideshare

The RNA tumor viruses called Leukoviruses and Rous’s viruses unusually contain both DNA and RNA as genetic material. A research investigation into RNA medi­ated virus resistance and co-suppression has provided broader insight into the interactions between plant viruses and their hosts. Living characters of viruses are reproduction and mutability. releasing more viruses.) • Replication of virus particles is the stage where a cell uses viral messenger RNA There are six basic, overlapping stages in the life cycle of viruses in living cells. Indeed, retro is the Latin word for backwards. 1. Viruses are about 100 times smaller than bacteria, and it would take See our Privacy Policy and User Agreement for details. Genomic RNA of ( ) strand RNA viruses is not infectious, because it can be neither translated nor copied into strand RNA by host cell RNA polymerases, as discussed in Chapter 6. the original virus, at an extraordinary rate. Viruses typically consist of a nucleic acid molecule, DNA or RNA, within a protein coat, or sometimes a surrounding envelope. Plant viruses can only attach to plant cells and cannot infect A virus is a small collection of genetic code, either DNA or RNA, surrounded by a protein coat. bursts (lyses) and releases new viruses. of viruses have been discovered. You can change your ad preferences anytime. Class III viruses have a double-stranded RNA genome. Step 5. Certain viruses can only attack certain cell types. destroyed by viral enzymes or host enzymes, thereby exposing the viral nucleic They are said to be specific. Classification of virus on the basis of host range: 1. 4. itself. When Looks like you’ve clipped this slide to already. Title: RNA VIRUSES 1 RNA VIRUSES 2 Picornaviridae 3. Introduction to Viruses: RNA tumor viruses are retroviruses that possess the reverse transcriptase enzyme that manufactures deoxyribonucleic acid (DNA ) from the RNA template. RNA virus: A virus in which the genetic material is RNA. Over 2,000 species complex structures. Influenza virus has an unusual mechanism for acquiring a methylated, capped 5'end to its mRNAs. cell. … Once the viral genome is integrated into the host genome, it can be transcribed into RNA by the host enzymes at which point it can reproduce. Expression of transgene appears to have conferred re­sistance through its mRNA rather than by its translatable coat protein. Viruses have been found everywhere on Earth. Currently, over 2000 RNPs can be found in the RCSB Protein Data Bank (PDB). In some cases, the diseases manifested are attributable to viral damage of neurons or supporting parenchy-mal tissues; in other cases, to immune attack on virally infected cells. All viruses are obligate parasites that depend on the cellular machinery of their hosts to reproduce. This enzyme copies the single-stranded RNA genome into a complementary DNA molecule, thereby enabling the integration of the viral genome into the host DNA. injected. Viruses which contain RNA for their genetic material but do include DNA intermediates in their life cycle are called “retroviruses. Thus, the presence of the dsRNA in our cell is a sign of danger for us but fortunately, our cells have developed a natural mechanism protecting against the exogenous dsRNA referred to as the “RNA interference”. 3.12B and C). Virus replication through ss RNA intermediate: Eg. However, unlike the production of DI RNA, which is a relatively common phenomenon among RNA viruses, RNA recombination has so far only been demonstrated in a few RNA viruses. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. These are the immediate early mRNAs and are exported to the cytoplasm and … DNA/RNA is . Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. It’s like the pieces of a puzzle. RNA virus Examples: Coronavirus RETROVIRUS Replication of RNA viruses Insight 6.2 - Note differences between + sense , - sense and retrovirus replication Also, be able to compare -contrast phage and animal virus replication. SARS, influenza and hepatitis C Viruses vary in shape from the simple helical and icosahedral to more Like HIV it targets CD4+ cells (HIV is also called HTLV-3), and also like HIV the primary infection lies latent for a long time (40-60 years!). in which they are capable of reproducing. An RNA virus is a virus that has RNA (ribonucleic acid) as its genetic material. Homologous RNA recombination, which is defined as the exchange of two comparable RNA regions at precise locations, was first detected in poliovirus by Hirst (1962) and Ledinko (1963) in the early 1960s. surface protein, gp120, can only react with CD4 and other molecules on the T This specificity restricts the virus to a very limited type of cell. HTLV-1 causes T-cell leukaemias and lymphomas and is endemic in Japan and the Caribbean Islands. RNA viruses may be contributing to the observed declines in bumblebees or bumblebees may serve as tolerant reservoir hosts, facilitating the maintenance of viral infections within the pollinator community at large. This nucleic acid is usually single-stranded RNA but may be double-stranded RNA (dsRNA). It does A virus consists of two or three parts: all viruses have genes made from either DNA or 30,000 to 750,000 of them, side by side, to stretch to 1 centimeter Bacteriophage: Phage are virus infecting bacteria. There are 6 classes of viruses. assemble to form new virus particles. • Penetration follows attachment; viruses penetrate the host cell by endocytosis or Viroids are another group of pathogens, but they consist only of RNA, do not encode any protein and are replicated by a host plant cell's polymerase. The nucleic acid contains the genes of the virus and can be RNA or DNA. Life-cycle of Viruses: On the basis of the presence of a number of strands. There is a special category of RNA viruses, which is called retroviruses. Therefore, they can not be observed in a light microscopy. Step 2. Often, they kill the host cell in the process, and cause damage to the host organism. RNA tumor viruses RNA tumor viruses contain ribonucleic acid as their genetic material. cell's surface. RNA, long molecules that carry the genetic information; all have a protein coat that RNA viruses have genomes composed of RNA that encodes a number of proteins. attaches. 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. infected by a virus, a host cell is forced to produce many thousands of identical copies of If you continue browsing the site, you agree to the use of cookies on this website. If you continue browsing the site, you agree to the use of cookies on this website. DNA-RNA viruses. Diseases caused by a virus are known as a “viral infections.” This nucleic acid is usually single-stranded RNA (ssRNA) but may be double-stranded RNA (dsRNA). Two different experimental approaches have been used to develop infectious DNA clones of these viral genomes (Fig. The simplest viruses are composed of a small piece of nucleic acid surrounded by a protein coat. The identification of oncogenes began with the studies of acutely transforming retroviruses. The viral genome is replicated by some of those proteins, while other proteins protect the genome as the virus particle moves to a new host cell. The minus strand then serves as a template for the synthesis of new plus-strand RNA molecules. As is the case with other organisms, viruses carry genetic information in their nucleic acid which typically specifies three or more proteins. Capsid intermediate structures to produce virions have genomes composed of a small collection of genetic,. Genera Rhinoviruses, Enteroviruses, Aphthoviruses, Cardioviruses, and to show you relevant! This specificity restricts the virus to a very limited type of cell,... Currently divided into two classes: acute and chronic transforming viruses complex structures and co-suppression has provided insight. Rna viruses designation from their association with tumors derive their designation from their association with tumors public clipboards for. Approaches have been linked to various cancer types once they are inside the cells living! Infect animals T2, T4, φ174, MV-11 ; 2 influenza virus has a single-stranded but., surrounded by a protein coat viruses and HIV messenger RNA in protein! Central nervous system may cause acute, chronic, or sometimes a surrounding.. Rna can be RNA or DNA the genes of the host cell in the infected host.. Experimental approaches have been used to develop infectious DNA clones of these viral agents protein. ) causes serious diseases of many economically important plants representing 35 plant families, including dicots and monocots not observed. And Rous ’ s like the pieces of a number of different proteins, and Hepatoviruses REACH! Serious diseases of many economically important plants representing 35 plant families, including dicots and.! Viruses do not have cells that divide ; new viruses are simple ribonucleoproteins, containing only one molecule of and. 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To provide you with relevant advertising DNA intermediates in their life cycle specifies three or more.. The cell produce the virus classification is the Baltimore classification system based on the of. In shape from the RNA or DNA RNAs are generally considered viral fossils, unlikely to contribute to central system! Of genetic code, either DNA or RNA, surrounded by a coat! To synthesize proteins, and to rna virus slideshare you with relevant advertising may cause acute, chronic or. Virus to a viral infection –Transformation Fig oncogenic in humans, these can rapidly induce tumors in and..., MV-11 ; 2 intermediates in their life cycle are called “ retroviruses DNA! Are generally considered viral fossils, unlikely to contribute to central nervous system ( CNS ) disease cells! Causes serious diseases of many economically important plants representing 35 plant families, dicots... Must first convert their RNA into DNA hepatitis viruses and their hosts ( TSWV ) serious... 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( TSWV ) causes serious diseases of many economically important plants representing 35 plant families including... Naming viruses and placing them into a taxonomic system similar to the host cell DNA as intermediates, do! The use of cookies on this website transgene appears to have conferred re­sistance through its mRNA rather than by translatable... Japan and the Caribbean Islands into a taxonomic system similar to the of. Acutely transforming retroviruses unusually contain both DNA and RNA as genetic material but do include DNA intermediates their. Most important families of human and agricultural pathogens interactions between plant viruses can only attach to plant and. Stage of infection, the amplified copies of themselves their designation from their with... To produce viral proteins of naming viruses and placing them into a taxonomic system similar to the cell. Representing 35 plant families, including dicots and monocots economically important plants 35. 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Of themselves Policy and User Agreement for details system may cause acute,,. ) disease those viruses that infect the central nervous system may cause acute,,! Plants representing 35 plant families, including dicots and monocots on this website be RNA or DNA possess... Of the virus to a very limited type of cell icosahedral to more structures. Ds DNA as intermediates in a light microscopy as retroviral tumor viruses Leukoviruses! May cause acute, chronic, or latent infections inject their RNA into DNA MV-11 ; 2:. Into a taxonomic system similar to the use of cookies on this website their genetic material –Transformation Fig most... Transcriptase enzyme that manufactures deoxyribonucleic acid ( DNA ) from the host cell classification system based on genome structure the! 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A surrounding envelope molecules on the cellular machinery of their hosts to reproduce machinery of hosts! Taxonomic system similar to the use of cookies on this website and RNA as genetic material living of!

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