Chapter 24: Orthomyxo and paramyxo viruses Flashcards
What is the genetic composition of orthomyxo and paramyxo viruses and how do they replicate?
Both are negative SS RNA viruses.
They require their negative RNA to be turned to a positive strand before producing proteins needed for production of new viruses.
What category of diseases are caused by orthomyxo viruses?
Influenza a,b,c
What are the category of diseases caused by paramyxo viruses?
parainfluenza virus Respiratory syncytial virus mumps measles metapneumovirus
What are the glycoproteins that cover the capsid of orthomyxo and paramyxo viruses?
HA and NA
hemagglutinin activity
neurominadase activity
How do the HA and NA glycoproteins differ from orthomyxo to paramyxo viruses?
Orthomyxo = separate entities that are specific to the subtype of influenza.
Mixes with other sources like pig and birds.
bound to the capsid with M protein
Paramyxo = combined entities that aren’t all that specific to any strain or used for any real identification.
What are the purposes of the HA and NA glycoproteins?
The HA is used to bind to erythrocytes and upper respiratory cells by the sialic acid receptor.
NA is used to cleave mucin that covers the receptor and can be used to cut away the mucin to release the newly formed viruses from the infected cell.
Define antigenic drift and shift.
Drift = small changes to an individual glycoprotein type that is specific to the virus. Shift = larger changes that affects either or both glycoproteins and makes it unidentifiable by the host and usually leads to epidemic.
Reye’s syndrome
A result of giving children aspirin for fever.
The body doesn’t properly digest it leading to liver pain and headaches.
The brain can actually get damage and it can lead to liver disease
What are the common symptoms of an influenza virus?
high fever and chills
headache, malaise and myalgias
Because it affects the upper respiratory system it leads to sore throat and dry cough
the nose can be runny/stuffy
It can cause a pneumonia or lead to lowered immune system to allow a secondary infection = bacterial pneumonia
Who most likely are affected by the flu?
Children, elderly and immunocompromised + people with chronic lung disease.
what are some extra symptoms experienced by more epidemic based flues?
They usually get GI involvement with nausea, vomiting and diarrhea
What sets H5N1 apart from many of the flues?
It is most aggressive in children.
What are the symptoms of parainfluenza?
Most adults will present with symptoms similar to that of a bad cold
Children and elderly + immunocompromised = upper respiratory infection = pnuemonia
What are croup and what paramyxo diseases exhibit this trait?
Croup is a swelling and narrowing of the larynx and upper airways leading to stridor or wheezing
seen in parainfluenza and some cases of metapneumovirus
What are the symptoms of respiratory syncytial virus?
Causes the infected cells to combine into giant cells.
Known to cause pneumonia in children less than 6 months old and otitis media of children
What are the glands most likely involved in mumps?
Parotid or salivary glands and in males it will eventually lead to pain or inflammation of the testes.
What are some the more serious problems with mumps?
Can cause meningitis and encephalitis
What paramyxo virus lacks NA glycoprotein?
Measles
Who are most at risk of damage from measles?
Measles is very detrimental to developing children and can lead to fetal death before birth or shortly after birth if mother is infected during the first trimester of the pregnancy.
How would a person present if they had measles in the prodromal stage of the illness?
The person would have conjunctivitis, swollen eyes and photophobia, high fever and hacking cough w/ malaise.
What are koplik spots and what disease does it present in?
They are red sores of the mouth that have white/blue centers
most commonly found in measles patients.
Describe the spread of the rash in measles patients.
The rash starts on the face and neck and moves down the trunk to the extremities in stages.
As it spreads it heals in the same order of presentation.
What does long standing measles lead to?
pneumonia, eye damage, myocarditis and encephalitis in the worst cases.
What is subacute sclerosing panencephalitis?
It is a slow progressing mental retardation seen specifically in measles patients.
