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Virology

PHRM 6101

QuestionAnswer
What is virology It's the study of viruses and virus-like agents under the umbrella of microbiology and medicine
What is a virus? sub microscopic entity consisting of a single nucleic acid (DNA or RNA, not both) surrounded by protein coat and capable of replication ONLY WITHIN the living cells of bacteria, animals or plants
what is a Virion? it is the entire virus (protein coat and nucleic acid)
simple structure of a virus perform complex functions (protection of the genome and entry of the virus to the cell)
repetitive structure of the virus generally made up of a very few proteins or proteins which are structurally very similar
high level of redundancy of a virus allows the partial inactivation of some parts of the virion without actually destroying the virions completely. poxvirus is an exception for all these
The genomes(sets of genes) may be - Double or single stranded DNA (dsDNA or ssDNA) - Double or single stranded RNA (dsRNA or ssRNA)
The nuclear material of a virsus may be ____ or ____ , single or _____ fragments linear, circular, multiple
What is a capsid The protein shell that covers the viral genome
what are capsomeres proteins subunits that build capsids
What is the most complex capsids that are found in viruses that infect bacteria? Bacteriophages - They have a protein tail piece with tail fibers that attach to the bacterium
What are the types of virus 1. Helical : capsomeres wrapped around nucleic acid 2. Icosachedral: simplest icosachderal is made of repeating capsomeres to capsulate the DNA and protect it
What is a host range each type of virus can infect and parasitize only a limited range of host cells
How do viruses identify host? using Lock and Key
Reproduction in a virus occurs in 2 cycles ** Lytic cycle : - culminates in the death of the host cell. - Virulent viruses reproduce only by lytic cycle ** Lysogenic cycle : - Replication of viral genome without destroying the host cell. - A temperate virus may reproduce by wither cycle
Why do viruses need a host cell. what does it provide it them? 1. Nucleotides 2. enzymes 3. Ribosomes 4. tRNA 5. Amino acids 6. ATP
What are the steps of Virus replication 1. virus attaches and enters 2. uncoating of virion 3. migration of genome nucleic acid to nucleus. 4. Transcription. 5. Genome replication. 6. Translation of virus mRNAs. 7. Virion assembly. 8. Release of new virus particles
dsDNA includes a nucleus while ssRNA does not Remember the drawing
What are Retroviruses Most complicated .. glycoprotein 120 binds to CD4 receptor .. they release genetic material and enzymes to the host cell .. Genetic material flows in the reverse direction .. RNA template transcribed to DNA(by enzyme reverse transcriptase)
What is a provirus once these viruses are acquired they tend to reoccur throughout a person's life.
What is an example of a virus that does not derive it envelope from the plasma membrane? Herpesvirus derives it from the nuclear membrane
Double stranded DNA (dsDNA) 1. DNA viruses replicates in the nucleus (except poxviruses) 2. DNA --> mRNA --> Capsid
Single stranded DNA(ssDNA) forms a double stranded DNA --> DNA-dependent DNA polymerase ---> undergo replication
What are some diseases caused by DNA viruses? common colds, warts, cold sores, and shingles
Where do RNA viruses infect animal cells and replicate? and is there a exception? in the cytoplasm. Exception: orthomyxoviruses and Retroviruses
Single stranded RNA (ssRNA) * Positive sense serves as mRNA --> synthesis viral proteins * Negative sense --> synthesis mRNA -->synthesis viral proteins. Bring RNA dependent RNA polymerase
double stranded RNA (dsRNA) * Positive sense RNA serves as mRNA --> synthesis viral proteins * Negative sense RNA --> makes more (+) RNA --> complete dsRNA --> package into new viruses
What are Rivoviruses? RNA viruses that exclude Retroviruses
What are some disease caused by RNA viruses? Influenza, hepatitis C, West Nile fever and polio
Respiratory transmission of virus include Influenza A virus
Faecal-oral transmission enterovirus (poliovirus)
blood borne transmission Hepatitis B virus and HIV
Sexual transmission HIV
animal or insect vectors Rabies virus
What can a virus do to cause a disease it can destroy the cell following infection . it can induce changes to cellular gene expression .. it may induce changes in the pattern of the immune response by the host
explain this: the link between viral infection and symptoms a virus produce is often obscure - some viruses damage or kill the cell by triggering the release of hydrolytic enzymes and lysosomes - others infect the cell to produce toxins - others have molecular components such as envelope protein that are toxic
what are some signals that induce immune response * production of double stranded RNA --> induce interferon * expression of viral proteins --> causes activation of T cells, natural killer cells * Formation of an inclusion body either within the cytoplasm or the nucleus --> visualized under microscope
is Papovavirus a DNA or RNA virus and what does it cause? dsDNA and it causes papilloma (human warts)
is adenovirus a DNA or RNA virus and what does it cause? dsDNA .. causes respiratory disease
is Herpesvirus a DNA or RNA virus and what does it cause dsDNA .. causes Herpes simplex I
is Poxvirus a DNA or RNA virus and what does it cause? dsDNA .. causes small pox, cow pox
is Parvovirus a DNA or RNA virus and what does it cause? ssDNA .. causes Roseola
Is Reoviruse a DNA or RNA virus and what does it cause? dsRNA .. causes diarrhea
is Picornavirus a DNA or RNA virus and what does it cause? ssRNA .. common cold (rhinovirus) and enteric intestinal virus
is Togavirus a DNA or RNA virus and what does it cause? ssRNA ... causes Rubella virus and yellow fever virus
is Rhabdovirus a DNA or RNA virus and what does it cause? ssRNA .. causes Rabies
is paramyxovirus DNA or RNA virus and what does it cause? ssRNA .. Measels, mumps
is Orthomyxovirus a DNA or RNA virus and what does it cause? ssRNA .. influenza virus
is Retrovirus a DNA or RNA virus and what does it cause? ssRNA .. RNA tumor virus
What are neuraminidase (NA) and Haemagglutinin (HA)? they act as antigens which are targets of vaccines
Antigenic drift small mutation and alterations of amino acids, especially in influenza A
Antigenic shift larger variations leading to epidemics and pandemics
TRUE/FALSE: RNA polymerase is NOT an error prone enzyme False .. it is
Epstein barr virus causes? Burkitt's lymphoma
human papillomavirus causes? benign warts and cervical carcinoma
Human T cell leukemia causes Leukemia
Hepititis C virus causes liver carcinoma
Are antibiotic effective against viruses? No they are powerless .. only vaccines
What are some drugs that combat viruses by interfering with viral nucleic acid synthesis 1. AZT - interferes with reverse transcriptase of HIV 2. Acyclovir inhibit herpes virus DNA synthesis
What are some problems with antivirals ? * difficulty in identifying virus specific target * Generation of resistant variants
Created by: amiqnais