RNA Virus - Myxovirus Flashcards
Myxovirus includes
Orthomyxovirus
Paramyxovirus
Members of Orthomyxovirus family
Influenza A, B and C
Members of Paramyxovirus family
M - Measles
M - Mumps
R - Respiratory Synctial virus
Parainfluenza
Nipah virus
Size and RNA form of Orthomyxovirus and Paramyxovirus
Orthomyxovirus - size : 110nm
RNA - Segmented
Paramyxovirus - Size : 150nm
RNA - unsegmented
Symmetry, RNA sense of Orthomyxovirus and Paramyxovirus
Both have helical symmetry
Both are enveloped
Both have Negative sense RNA
Types of Influenza viruses
Influenza A - 8
Influenza B - 8
Influenza C - 7
Structure seen on Influenza viruses
Hemagglutinin (HA)
Neuraminidase (NA)
M1 And M2 Protein
Hemagglutinin shape and attaches to
More in number
Triangular in shape
Attachment to Sialyl acid receptor (Resp. Epithelium, RBC)
Neuraminidase Shape and functions
AKA
Less in no.
Mushroom shaped
Helps in release of virus
AKA - Receptor destroying enzyme (RDE) or Sialidase
M1 protein function
Beneath envelope
Maintains structural integrity
M2 protein Features
Ion channel - H+ influx
Aid in uncoating of virus
Pathogenesis of Influenza viruses
Attachment of Hemagglutinin on Sialyc acid receptor - internalized by endocytosis - Uncoating (by M2 protein by causing H+ influx) - Then negative sense RNA is converted to Positive RNA sense with help of RNA Dependent RNA Polymerase - release of virus with the help of Neuraminidase
Group specific typing of Influenza viruses
1);Influenza virus A - Human and animals, Antigenic shift, Epidemic and Pandemic
2) Influenza virus B - Humans only, No antigenic shift, Seasonal flu
3) Influenza Virus C - Non pathogenic
Difference between antigenic shift and antigenic drift
1) Antigenic shift : Sudden change
Antigenic drift : Gradual change
2) Antigenic shifting : Exchange of RNA segments b/w Influenza A (Genetic reasortment)
Antigenic drift : Mutation in H and N
3) Antigenic shift : cause major epidemics and Pandemics
Antigenic drift - doesn’t cause
4) Antigenic shift - Seen in Influenza A
Antigenic drift - seen in Influenza A and B
Currently circulating strains of Influenza viruses
Type A/H1N1 : WHO declared in pandemic on 11th June 2009
Type A/H3N2
Type A/H5N1
Type B
Incubation period of Influenza viruses
18-72 hours
Clinical features of Influenza
Fever, headache
Sore throat
Myalgia
Runny nose is usually absent
Rarely GI Symptoms
Reye Syndrome AKA Jamshedpur fever
Complication and M/C Extrapulmonary symptom of Influence
Complication - Pneumonia
M/C extrapulmonary symptoms - Myalgia
Influenza samples are stored in which media
VTM (Viral transport media)
Isolation of Influenza is done on
Amniotic cavity of embryonated egg
Cell lines (1° Monkey kidney)
Antigen detection test for Influenza
Direct immunofluorescence
Antibody detection of Influenza
ELISA - 2 sample to be taken with gap of 2 weeks - 4 fold gap increase
Hemagglutination Inhibition test (HAI)
Hemagglutination Inhibition test Procedure
1) RBC - No reaction
2) RBC + virus (influenza) - Hemagglutination - Mat/Carpet Formation
3) RBCs + virus + Antibody (pt. Sample) - Antibody combines with Antigen - Hemagglutination Inhibition
Which tests are sensitive and specific for Influenza
RT PCR
Real Time PCR
Neuraminidase inhibitors given by oral route
Tamiflu/Oseltamivir
Neuraminidase inhibitor given by Inhalation route
Zanamivir/Relenza
M2 Inhibitors used for Influenza A
Amantadine
Rimantidine
Vaccines used against Influenza
Live Nasal spray -
Inactivated vaccine - Given to healthcare professionals, two doses given annually
Live Nasal spray vaccine for Influenza indications and C/I
Trivalent vaccine - H1N1, H3N2 and Type B
Indicated - 2-49 years of age
C/I - if low immunity
Paramyxovirus features
Single Unsegmented RNA
Hemagglutinin and Neuraminidase on same spike
F Protein (Fusion protein)
Paramyxovirus includes
Measles
Mumps
Respiratory Synctial virus
Parainfluenza
Nipah virus
Measles also known as
Rubeola
Incubation period Measles, Mumps and Rubella
Measles - 10day (Children), 21 days(Adults)
Mumps - 19day
Rubella - 14day
Transmission of Measles virus
Inhalation of respiratory droplets
Period of communicability of Measles
4 days before and 4 days after rash
Immunity after Measles infection
Lifelong because of single serotype
Prodromal symptoms of Measles
3C
Coryza
Cough
Conjunctivitis
Fever
First manifestation of Measles infection
Fever (10th day)
Pathognomonic signs of Measles virus
Koplik spots (12th day)
Koplik spots features
White spots on erythematous base
Seen near molars 2-3 days after fever
When rash appears in Measles and it’s features
On 14th day
Maculopapular rash
Begins behind the ears then on face followed by trunk
Fades thereafter in same order
When rash appears, Fever and Koplik spots disappear
Complications of Measles
1) Sec bacterial infections - Otitis media, Bronchopulmonary pneumonia
2) CNS Manifestations
3) In pregnancy - Intrauterine Death
4) A/w diarrhea, Pneumonia
Type of Pneumonia caused due to measles and histological finding
Hecht’s Pneumonia AKA Giant cell Pneumonia - Warthin Finkaldey giant cells
CNS Complications caused due to Measles
1) Post measles encephalitis - Antibody antigen myelin basic protein
2) SSPE (Subacute Sclerosing Panencephalitis) - occurs after 7-13 years - fatal after 1-3 years
Cell line recommended by CDC in case of Measles
Vero
Cytopathic effect seen in Measles infection
Warthin Finkaldey giant cells
Vaccines strains For Measles and S/E
Edmonston-Zegreb strain - used in India
S/E - Mild measles like disease
Toxic Shock Syndrome (contamination of vial with S. Aureus)
Commonly affected age group by Mumps virus
5-9 years age group
Incubation period and Period of communicability of Mumps infection
IP - 19 days
Period : 1 week before and 1 week after symptoms
Most common clinical features of mumps
Inapparent - causes few or no signs or symptoms
Most common manifestation of Mumps
Bilateral Parotitis - pain increase on citrus juices
2nd most common manifestation in Mumps
Unilateral orchitis - doesn’t lead to Sterility
Other clinical features of Mumps
Aseptic meningitis
Oophoritis in females
Pancreatitis
Mumps virus multiply in which organ
Multiply in lungs - spill in blood -Organs
Atypical mumps means
Directly meningitis without parotid involvement
Diagnosis of Mumps
Antigen
Antibody - ELISA
RT PCR
Culture/cell lines
Recommended strain for Mumps vaccine
Jeryl Lynn strain
Vaccines for Mumps
MMR
MMR-V - V is varicella
B/L parotid gland involvement seen in case of Child and adult smoker
Child - Mumps
Adult smoker - Warthin’s tumor
Types of Respiratory Synctial virus and which one is more severe
RSV A and B
RSV A - More severe
Clinical features seen RSV infection in infants and adults
Infants - M/C cause of Lower resp tract infection - Fever, Rhinorrhea, Cough,Dyspnea, Wheezing
Adults - causes Upper resp tract infection
Age group mostly affected by RSV virus
6 weeks to 6 months
Microscopic finding in case of RSV infection
Giant cells
Which is most sensitive diagnosis method for RSV infection
Virus isolation - on HeLa , Hep2
Cytopathic effect seen in case of RSV infection
Synctium formation - Multinucleated giant cell
Treatment of RSV infection
Newer drug - Palivizumab (against Fusion protein)
For severe infections - Ribavirin
RSV infection is more common in which season
Rainy
Parainfluenza virus is commonly seen in which season
Worldwide winter
Clinical features in Parainfluenza infection
M/C symptom - common cold
Children - Croup
Severe cases - Pneumonia
Most common complication of Parainfluenza virus
Otitis media
Clinical features of Nipah virus infection
Encephalitis
Fever
Nipah virus Mnemonic
NIPAH
N- Nervous System - 60-70% mortality
P - Pigs (amplifier)
Animal - Human
Vector in case of Nipah virus infection
Fruit bat
Transmission of Nipah virus and it’s amplifier
Bat’s urine contaminating food and water
Patient secretions
Amplifier - Pigs
