Table of Contents
What are the 4 types of influenza viruses?
There are four types of influenza viruses: A, B, C and D. Human influenza A and B viruses cause seasonal epidemics of disease (known as flu season) almost every winter in the United States. Influenza A viruses are the only influenza viruses known to cause flu pandemics, i.e., global epidemics of flu disease.
What is the biology of influenza?
Influenza viruses belong to the family Orthomyxoviridae. The viral particles are about 80-120 nm in diameter and can be spherical or pleomorphic. They have a lipid membrane envelope that contains the two glycoproteins: hemagglutinin (HA) and neuraminidase (NA).
What is influenza virus PDF?
Influenza Virus Influenza is a single-stranded, helically shaped, RNA virus of the orthomyxovirus family. Three types of influenza virus are known to affect humans: A, B, and C. Type A influenza has subtypes determined by the surface antigens hemagglutinin (HA) and neuraminidase (NA).
What is influenza virus in microbiology?
The orthomyxoviruses (influenza viruses) constitute the genus Orthomyxovirus, which consists of three types (species): A, B, and C. These viruses cause influenza, an acute respiratory disease with prominent systemic symptoms.
What is a characteristic of influenza?
Uncomplicated influenza illness is typically characterized by the abrupt onset of constitutional and upper respiratory tract signs and symptoms (e.g., fever, chills, myalgia, headache, malaise, nonproductive cough, sore throat, and rhinitis).
What kind of virus is influenza?
Influenza viruses are members of the family Orthomyxoviridae. This family represents enveloped viruses the genome of which consists of segmented negative-sense single-strand RNA segments.
What are the functions of influenza virus?
The influenza virus NA executes several functions. Firstly, its activity is required at the time of the budding of newly formed viral particles from the surface of the infected cell, to prevent aggregation of viral particles.
What is the life cycle of influenza virus?
The influenza virus life cycle can be divided into the following stages: entry into the host cell; entry of vRNPs into the nucleus; transcription and replication of the viral genome; export of the vRNPs from the nucleus; and assembly and budding at the host cell plasma membrane.
Is the influenza virus DNA or RNA?
-stranded RNA
All influenza viruses consist of single-stranded RNA as opposed to dual-stranded DNA. The RNA genes of influenza viruses are made up of chains of nucleotides that are bonded together and coded by the letters A, C, G and U, which stand for adenine, cytosine, guanine, and uracil, respectively.
What is the agent of influenza?
INFECTIOUS AGENT Influenza is caused by infection of the respiratory tract with influenza viruses, RNA viruses of the Orthomyxovirus genus. Influenza viruses are classified into 4 types: A, B, C, and D. Only virus types A and B commonly cause illness in humans.