Microbiology related 1. Poliovirus is a Group IV virus containing a positive str
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Question
Microbiology related 1. Poliovirus is a Group IV virus containing a positive stranded RNA genome (Baltimore ciassification-see Fig 6.15). Influenza virus is a Group V virus and Human Immunodeficiency Virus (HIV) is a group VI virus. Complete the table below for each of these viruses to include the order in which the following steps first occur: receptor binding, genome entry, synthesis of viral mRNA, translation of viral proteins, replication of new viral genomes, and packaging of genomes into progeny virions. The life cycle figures in your textbook should be very heipful.. Poliovirus Influenza HIV receptor binding genome entry synthesis of viral mRNA translation of viral proteins Synthesis of template for genomic and 2 Adc > Dele rotat mRNA packaging of genomes into progeny virionsExplanation / Answer
In case of Polio virus- It is a +ve stranded RNA virus, genome inside virus particle is used as a m-RNA and ttranslated by host cellimmedictaely after entry . virus dominates the cell translation machinery and inhibits cellular protein synthesis, 5' end of polio virus is extremely long and it directs the translation of viral protein. The polyprotein is cleaved, and produces mature viral proteins The positive-sense RNA acts as a template for complementary negative-strand synthesis, producing double-stranded replicative form . Many positive strand RNA copies are produced from the single negative strands. The newly synthesized positive-sense RNA molecules acts as templates for translation of more viral proteins or are enclosed in capsids finally progeny virions are produced and after lysis of the infected cell infectious progeny virions are released.
In case of Influenza virus- After release into cytoplasm , VRNP enters nucleus , viral proteins which make VRNP, are NP, PB1,PB2 they are the nuclear organization signals and they can bind to cellular nuclear import machinery and enter nucleus.
Influenza virus are made up of - ve sense strands of RNA , The genome to get transcribed must be first converted to +ve sense RNA strand to act as a template. for production of viral RNA.
Replication of genome do not require a primer Vral RNA dependent RNA polymerase initiates synthesis of RNA, internally on viral RNA. Translation of viral protein occurs and at the end packaging of genome into progeny virus occurs and released.
In case of HIV virus- the life cycle consists of 7 phases they are i) Binding, ii) Fusion, iii) Reverse transcription iv) Integration v) Replication vi) Assembly vii) Budding.
HIV virus is a Lenti virus , it is transmitted as a S.S. positive sense enveloped RNA virus , when it enters target cell viral genome converted into D.S.DNA by a virally encoded enzyme Reverse transcriptase . It is transported along with viral genome into virus particle, Viral DNA goes into cell nucleus and integrate into cellular DNA by integrase enzyme, once integrated virus becomes latent or remains dormant for around 10 years and it becomes undetectable, or integrated viral DNA may be transcribed producing new RNA genome and viral proteins using host cell resources, and are packaged and released from cell.
Polio virus Influenza Virus HIV virus Receptor binding 1 1 1 Genome entry 2 2 2 Synthesis of Viral m-RNA 5 4 3 Translation of Viral Protein 3 5 5 Synthesis of Template for Genomic and mRNA 4 3 4 Packaging of genomic into progeny virus 6 6 6