Orthomyxoviridae and Paramyxoviridae Lecture Review

Flashcards on Orthomyxoviridae and Paramyxoviridae viruses, covering their structure, replication, transmission, and associated diseases like influenza, measles, and mumps.

Orthomyxoviridae

Family of RNA viruses with a negative-sense ssRNA and a segmented genome, allowing for gene reassortment. Includes Influenza A, B, and C.

Paramyxoviridae

Family of RNA viruses with a negative-sense ssRNA and a non-segmented genome. Includes Measles, Mumps, and RSV.

Hemagglutinin (HA)

Attachment protein of influenza that binds to sialic acid receptors and mediates membrane fusion.

Neuraminidase (NA)

Enzyme of influenza that releases viral particles after maturation and breaks down mucins in the respiratory tract.

Antigenic Shift

Reassortment of HA and NA genes in influenza viruses, leading to novel antigenic properties and potential pandemics.

Antigenic Drift

Point mutations in antigenic sites of HA in influenza viruses, leading to seasonal flu and the need for new vaccines.

Endemic

Normal yearly circulating flu virus that peaks in the cooler/drier season

Epidemic

A disease outbreak that substantially exceeds what is expected, usually in a particular region

Pandemic

An epidemic that spreads throughout a larger region, like a continent, or worldwide.

R0 (Basic Reproductive Number)

A measure of how contagious a disease is; the average number of people an infected person will transmit the virus to in a completely susceptible population.

R0 < 1

Infection that will die out in the long run.

R0 > 1

Infection that will be able to spread in a population.

Mumps

Clinical symptoms include coldlike symptoms and progressive swelling of one or both parotid glands; transmitted via respiratory droplets and direct contact.

Measles

Clinical symptoms include high fever, cough, runny nose, inflamed eyes, Koplik’s spots, and a red, flat rash.

Koplik's spots

Small white spots that may form inside the mouth and are diagnostic for measles.

Transcriptional Polarity in Paramyxoviruses

Negative-sense RNA genome of paramyxoviruses is transcribed from only one promoter

Orthomyxoviridae

Segmented (-) RNA genome; reassortment possible; e.g., Influenza A, B, C

Paramyxoviridae

Non-segmented (-) RNA genome; no reassortment; e.g., Measles, Mumps, RSV

Hemagglutinin (HA)

Attachment and membrane fusion; binds to sialic acid receptors.

Neuraminidase (NA)

Viral release and spread; cleaves sialic acid on surface for release.

Antigenic Shift

Reassortment of HA and NA genes, leading to novel antigenic properties and potential pandemics

Antigenic Drift

Point mutations in HA due to error-prone RNA polymerase, requiring new vaccines yearly.

Mumps Symptoms

Cold-like symptoms, fever, headache, swelling of parotid glands (parotitis).

Measles Symptoms

Cold-like symptoms, high fever, cough, runny nose, inflamed eyes, Koplik’s spots (small white spots), red rash.

R0 (Basic Reproductive Number)

Average number of new infections that a single infected individual will cause in a population.