Week 3 Day 2 Respiratory and Enteroviruses Flashcards
3 proteins on Influenza and where are they located?
All surface proteins.
Hemaggluttinin (HA)
Neurominidase (NA)
M2 Ion Channel
What is HA (Hemagglutinin) and what does it do?
- Found on the surface of influenza viruses
- Binds Sialic Acid receptors to aid in viral entry
- Agglutinates RBCs
- antigenic neutralizing, antibodies can bind to HA and neutralize the virus
What is neuraminidase aka NA?
A influenza surface protein that allows the replicated virus to exit a cell by by cleaving sialic/neuraminic acid.
Degrades mucin
When antibodies bind it doesn’t neutralize the virus but does slow the spread- makes sense as NA degrades mucin and is used to escape and spread mucin slows bacterial spread
What is an M2 Ion Channel and what does it do? Which drugs target it?
An influenza virus transmembrane channel
Only found in Influenza A
Target for drugs amantidine and rimantidine
What are the 3 human influenza sub groups and who do they infect?
A- humans and animals, most severe/virulent- most spread, has HA, NA and M2
B- humans only- FYI only no M2 have BM2 instead
C- humans only and not assoc with epidemics and pandemics no HA or NA and has CM2 not M2
Lack of M2 is Why most antivirals only work on A
For A and B flu what are the serotypes and how are the designated?
16 different HA types and 9 NA types
The subtypes are name after the combination of HA and NA
H1N1 H9N3 etc
2 types of antigenic changes?
Drift and Shift
What is antigenic drift in flu?
Epidemic causing-
Minor changes in surface proteins HA and NA with seasons
Happens in all subtypes A, B and C
What is antigenic shift in flu?
Pandemic causing- Total change in HA and NA or both
Happens in a cell infected with 2 strains or more strains and the proteins get mixed up
Requires animal intermediate
How is influenza spread?
Droplets, fomites and aerosol
Non-porous surfaces- 48 hrs
Clothing- 12+ hrs
Influenza incubation period?
1-4 days
Upper respiratory viruses?
FYI- familiar only-mark blue to skip
Rhino, Corona, flu, Paraflu, RSV, herpes, Adeno and Coxsackie
Lower respiratory viruses?
FYI familiar only-mark blue to skip
Flu, paraflu, RSV, adeno and metapneumo
Influenza symptoms?
Abrupt onset of: Fever Myalgia and malaise Headache Pharyngitis Rhinorrhea Cough
Lasting 5-7 days but can have a long tail of symptoms
When is flu infectious?
3-5 days after symptoms begin in most adults
Longer in kids and immune compromised
Why can flu be such a challenge to control?
Easily spread and hard to diagnose
Why is flu hard to diagnose?
Overlapping symptoms with RSV and rhinovirus
FYI only
They tend to present with more nasal congestion and respiratory problems and less fever and exhaustion where as flu is primarily fever and exhaustion with some respiratory issues
Major complication of flu and two types of it?
Pneumonia-
Primary- caused by the virus itself
Secondary- caused by an opportunistic bacteria that infects when the immune system is busy fighting the virus and
When Flu causes primary pneumonia how bad is it?
Pretty bad- 10-20% respiratory failure
What bacteria tend cause secondary flu pneumonia and how?
S. pneumoniae, S. aureus, H. influenzae
More common than primary flu pneumonia
Influenza virus degrades mucin and depresses immune system and primes body for bacterial infection
FYI
Sometimes patient starts to get better then gets worse
Immune impaired patients sometimes benefit from prophylactic antibiotics when sick with flu virus
Main pneumonia causing viruses by age group?
Neonates- Infants- Children- Young Adults- Old Adults
FYI be familiar
Neonates- RSV Infants- RSV and Parainfluenza Children- RSV and Parainfluenza Young Adults- various Old Adults- Influenza
Bacteria or viruses- which are the main cause of CAP (community acquired pneumonia)?
Virus
Another weird complication of viral infection (flu being one of the two main virus linked to it) in children?
One other thing that is linked to it?
Reye’s syndrome
Aspirin has been linked to it but no mechanism found
What is Reyes Syndrome?
Rare life threatening-supportive care only
Happens after viral infection- mainly flu and chicken pox
Fever, rash, encephalopathy, liver failure
Possibly causes Carbamyl phosphate synthetase and ornithine transcarbamylase deficiency
Most common way flu is diagnosed?
Rapid PCR- greater than 95% specific and sensitive, take 20-60 minutes
Some are CLIA waived- meaning they can be performed at home or in non-certified labs such as a doctors office, drugstore or pharmacy
Other influenza diagnostic tests not really used?
FYI- be familiar only
Serology HA assay- research only Viral tissue cultures- slow Direct fluorescent antibodies-only work with high viral load RT PCR-take time Rapid antigen- not sensitive
What is the best way to prevent flu?
Hygiene and highly effective 70-90% vaccine
Two types of antiviral flu treatments?
Neuraminidase Inhibitors and M2 Blockers
More on NA inhibitors?
Work for A and B
Can uses prophylactically
Work best is used early- difficult
Zanamivir (inhaled) and Oseltamivir/Tamaflu (oral)
More on M2 blockers?
Work on A only
Problems with resistance
Not recommended in US
Amantidine and Rimantidine
Types of flu vaccines and purpose of them?
Inactivated and live attenuated
Used to Prevent severe complication not infection
Viruses that cause upper respiratory viruses that she wants us memorize?
Rhinovirus Coronavirus RSV/Respiratory Syncytial Virus Adenovirus Coxsackievirus (a specific enterovirus)
2 of the Viruses that cause upper respiratory viruses that she wants us memorize that ALSO cause LOWER respiratory infections?
In red/Memorize
RSV and
Adenovirus
More about rhinovirus?
5 points
Greater than 150 different antigenic types- many circulate simultaneously
Kids get 5-12 a yr
No vax and no proven effective tx
Relatively Stable to disinfectants!
Emerging cause of lower respiratory tract disease. Mutations?
How is adenovirus transmitted and treated?
Droplets and fecal oral
No specific tx supportive care
What does adenovirus cause aka symptoms?
Pharyngitis, pneumonia, conjunctivitis, gastroenteritis, acute respiratory diseases
Connections between subtypes and syndrome types - 3 and 7 swimming pools, Type 4 military recruits
Is there a vaccine for adenovirus?
Yes only for one subtype 4 given to military people only
Couple points about RSV infections?
No vaccine
Can be severe in infants and elderly
What type of well known virus causes 5-30% of common colds and how many serotypes of it are there?
Coronaviruses
Unknown number of serotypes
3 major corona virus caused epidemic/pandemics?
SARS - 2003
MERS - 2013. Zoonotic
SARS Cov-2 aka Covid 19
What part of the body do entroviruses infect and are humans the only natural host?
Human are only host and they can infect both the GI and Respiratory tracts
Can cause meningitis and muscle infections (coxsackievirus)
Coxsackievirus and polio are famous ones
Also Coxsackievirus combined with enterovirus A-71 (Hand Foot and Mouth)
What in our innate immune system recognizes enteroviruses to try to fight them off and what is the main immune responses are triggered?
TLR3’s are the most important PRR for enteroviruses
Responses via Type 1 interferons and IgA
How acid-stable are enteroviruses?
Very- they can pass though our entire GI tract and emerge immediately infectious
3 major groups who are at risk from enteroviruses and what time of year do most case occur?
Most cases occur in the summer and fall.
Neonates
Antibody deficient patients
Stem cell transplant patients
What do Neonates get from enteroviruses?
Fever and sleepiness due to Sepsis and multi-organ failure
10% have seizures
What do Antibody-Deficient patient get from enteroviruses?
Persistent CNS infections
What do Stem Cell Transplant patients get from enteroviruses?
Multi- Organ disease
An enterovirus that causes upper Respiratory tract infections mostly in children?
Coxsackievirus causes Herpangina
What is Herpangina and what are the symptoms?
An upper respiratory tract infection of Coxsachievirus A that has only Oral symptoms and no systemic symptoms
Ulcers/erythematous papules or small vesicles with erythematous base that are on the posterior palate, pharynx, tonsils and sometimes outside the mouth
Often accompanied by high fever
Self limiting
What is a common symptom caused by different enterovirus serotypes infections?
Rashes
They are often a result of the secondary viremia which passes the infection to other tissue aka the skin
Famous enterovirus caused Rash syndrome and the symptoms?
Hand Foot and Mouth Disease
Caused by Coxsackievirus and Enterovirus A-71
Sores in mouth and rash on hands and feet
Two infections of muscle caused by Coxsackievirus and the symptoms?
Myositis- infected muscles both striated and cardiac- muscles sore to touch and difficulty walking due to pain
Myocarditis and pericarditis- disfunction of heart and cardiac failure
What would the cerebrospinal fluid look like if the meningitis was caused by an enterovirus?
WBC count- Med high ++
WBC type- Lymphs
Glucose- normal
Protein- Med high ++
What is the most common cause of viral meningitis/encephalitis and how does it present?
Enterovirus- Acute onset fever, Headache, Meningismus (stiff neck), Photophobia, Emesis (🤮), Maybe rash and other typical enterovirus symptoms
What diseases can Enterovirus serotype A-71 cause?
Hand Foot and Mouth Disease (HFMD), Severe neurological (meningitis) and cardiovascular disease (Myocarditis)
Famous enterovirus that has been largely eradicated due to a vaccine introduced in the 1950s and what type of vaccine is given in the US?
Polio
Inactivated virus vax is given in US
