Viral Agents Flashcards
structure of a virus?
protein capsid surrounds DNA or RNA, never both. no enzymes.
Positive vs Negative strand RNA virus
positive strand is like mRNA and can be translated immediately.
Negative stand must be transcribed into a positive stand to be translated into protein. this is done by an RNA dependent RNA polymerase.
how do retroviruses replicate?
they use a reverse transcriptase to turn their RNA into DNA and add it to the host genome.
double stranded RNA virus
retrovirdae, including rotavirus is the only virus with double stranded RNA genome
Negative vs Positive strand in DNA viruses?
the negative strand is the strand that is transcribed inot mRNA and the pos strand is ignored.
explain how a capsid is made
a capsid is a made from capsomer building blocks. glue them together into a triangle, then add 20 triangles together and a capsid is formed!
naked for enveloped virus
enveloped has a plasma membrane surrounding it.
naked viruses don’t.
Name the DNA viruses
HHAPPPy: Herpes Hepandna Adeno Papova Parvo Pox
where do DNA viruses replicate vs RNA viruses?
DNA - nucleus
RNA - cytoplasm
Single stranded DNA Virus
Parvoviridae
very complex virus with double stranded DNA , coding for hundreds of proteins. it is surrounded by box proteins and replicates in the cytoplasm, not nucleus.
Poxviridae
DNA viruses with envelopes?
Herpes, Hepadna, Pox
three naked DNA viruses
Papova, Adeno, Parvo
four exceptions for RNA viruses
- reoviridae is double standed RNA
- three are enveloped : Picoma, Calici, revirdae
- five have icosahedral symmetry: Reo, Ricoma, Togo, Tlavi, Calici
- (Rhabdo has helical symmetry and its shaped like a bullet.
enzymes to replicate RNA
Replication:
POSITIVE RNA = have the RNA dependent RNA polymerase
NEGATIVE RNA = VIRON RNA POLYMERASE
steps in DNA transcription and translation of viral DNA
early vs late
early transcription = translation of proteins for DNA and replication
Late Transcription = translation of structural proteins and assembly.
possible host cell outcomes when Viral DNA replicates
Host cell outcomes:
- Death: shuts down the host cell and only does viron replications.
- Transformation: infection can induce oncogens resulting un uncontrolled and uninhibited cell growth.
- Latent infection: can sleep within the cell, making it clinically overt. varous factors can reactivate it later.
- Chronic Slow infection: can cause disease in many years, or decades, or indolent infection.
1-2 day incubation period.
Viral structure: spherical, with 8 segments on NEGATVIE stranded RNA put together with a protein called nucleocapsid protein (NP).
Orthomuxovirdae
outer proteins of influenza virus?
Outer proteins:
Hemaggultinin Activity (HA) - they attach to Silalic Acid receptors and cause heme-agglutination of RBC. needed for absorption in the upper respiratory tracts.
Neuraminidase (NA) - mucin is a part of the upper respiratory tract. NA cleaves neuramic acid and disrupts the mucin barrier, exposing the sialic acid binding sites beneath. NA then cleaves the sialic acid receptors when the virons are leaving the cells.
Influenza A vs B/C
Influenza A = mammals, Influenza B and C are in humans.
what is worse the flue or influenza?
who is at risk?
Influenza virus > The Flue; Pneumonia at risk groups, more severe risk groups.
define epidemic influenza
within the winter (Dec- Early March) is an outbreak in a city, state, or entire country. first sign is otitis media or pneumonia in children with secondary pneumonia in adults. this is followed by death in elderly and immunocompromised (chronic diseases).
high fever, chills (frank shaking chills), headache, malaise (feeling like shit), and myalgia (muscle aches)
the flu
dry cough, sore through, rhunorrhea (runny clogged nose), painful muscle aches, high fevers, and headaches set this apart from a mild cold.
URI
much more severe outbreaks. with common seconday infections: bacterial pneumonia, or otitis media (staphlococcus aureus, Haemophilus influenzae, or strepococcus pneumoniae.
Pandemic influenza
ab immunity, vaccines, and ativiral drugs that depend on the viral structure.
Neuroamindase inhibitors
slight changes in the viral coating
Antigentic drift
HUGE changes in the viral coating. causes pandemics due to not having any Abs to protect the humans from the infection.
antigenic shift
originally swine. caused the 1918 spanish flue
H1N1
Is avian virus emerged in 1997
H5N1
Complications of infuenza
Reye’s syndrome = head and liver disease due to giving a child asprin and not acetominophin.
Diagnostic tests for influenza (4)
Diagnostic tests:
- viral isolations. culture for genetis and antigenic analysis.
- detection of viral proteins: new one hour tests help guide the choice of antiviral agents.
- detection of viral RNA with PCR
- serological diagnostics: 4 fold increases in specific abs over 2 weeks.
(2-4 days incubation - Max is 8)
high fever, headache, myalgias, muscle aches, diarrhea, abdominal pain, vomiting, sore throat, rhinorrhea,
lower respiratory tract: cough, shortness of breath, production of sputum.
Acute respiratory distress syndrome: low blood oxygen levels, infiltrates in multiple parts of the lungs, no evidence of heart failure.
50% of people die and 90% of people under 15 years old die.
H5N1
Diagnosis for H5N1
Diagnosis H5N1: viral culture or reverse PCR of pharyngeal or nasal washings, or feces. Abs for H5 or a four fold in H5 titers.
- a single negative strand that isnt segmented.
- HA and NA are one glycoprotein.
- Fustion (F) protein to infect multinucleated giant cells.
- Lungs - replication in upper respiratory tract.
- Kids - most common infections.
- Viremia - viral infection that results in dissemination to distant sites.
Paramyxovirdae Characteristics
Parainfluenza virus and respiratory syncytial virus (RVS) are the main causes of what two things?
(1) Bronchiolitis, viral pneumonia, croup (in children),
(2) cold/flu in adults
stridor (wheezing)and a barking cough
Croup
Most common cause of pneumonia in children less than 6 months of age?
RVS (F protein and lacks HA and NA. not immune. )
upper and lower respiratory tract infections. primarily in young children and older adults. Second most common cause of lower respiratory tract infections. >1 year. bronchiolitis, croup, pneumonia. diagnose with PCR.
Matapneumovirus
parotits, testicular inflammation, upper respiratory tract and lymph nodes, PAROTID and TESTES (orchitis)
Mumps virus causes mumps
prodrome, koplik’s spots, rash, encephalitis
10 day incubation, 3-4 days prodrome (conjuctivitis, swelling of eye lids, photophobia, fever 105, hacking cough, rhinitis, and malaise), 1-2 days Koplick spots and small red lesions with blue center in the mouth, 6 days of a rash - head to toe
Measles (rubeola) virus > Measles
Complications Of Paramyxovirdae
pneumonia, eye damage, heart involvment, encephalitis is rare. spontaneous abortion, premature delivery, fetal death,
Subacute Sclerosing Panencephalitis (SSPE)
Subacute sclerosing panencephalitis (SSPE) due to the measles virus causing slowly progressing central nervous system disease, with mental deterioration and incoordination.