Dictionary > Influenza virus

Influenza virus

Influenza virus
(Science: organism, virology) member of the Orthomyxoviridae that causes influenza in humans. There are three types of influenza virus.
Each type of virus has a stable nucleoprotein group antigen common to all strains of the type, but distinct from that of the other type; each also has a mosaic of surface antigens (haemagglutinin and neuraminidase) which characterise the strains and which are subject to variations of two kinds: 1) a rather continual drift that occurs independently within the haemagglutinin and neuraminidase antigens; 2) after a period of years, a sudden shift (notably in type A virus of human origin) to a different haemagglutinin or neuraminidase antigen. The sudden major shifts are the basis of subdivisions of type A virus of human origin.
type A causes the world wide epidemics (pandemics) of influenza and can infect other mammals and birds.
type B only affects humans.
type c causes only a mild infection.
types a and B virus evolve continuously, resulting in changes in the antigenicity of their spike proteins, preventing the development of prolonged immunity to infection. The spike proteins, external haemagglutinin and neuraminidase have been studied as models of membrane glycoproteins.
strain notations indicate type, geographic origin, year of isolation, and, in the case of type A strains, the characterizing subtypes of haemagglutinin and neuraminidase antigens (e.g., A/Hong Kong/1/68 (H3 N2); B/Hong Kong/5/72).


You will also like...

Hominid
The Hominids

The hominid family diversified from the apes around 6 to 8 million years ago. Since then, the evolutionary path has prov..

green leaf - close up view
Leaves

Leaves are the major photosynthetic organ of a plant. Apart from that, they are also crucial to water movement. In this ..

Population Growth and Survivorship
Population Growth and Survivorship

This lesson looks at population attributes, regulation, and growth. It also covers population genetics, particularly gen..

Plant Auxins
Plant Auxins – Phototropism & Geotropism

Plants produce hormones to regulate their growth. Auxins, for instance, influence plant growth. Know the role of auxin i..

Lights' Effect on Growth
Lights’ Effect on Growth

This tutorial elaborates on the effect of light on plant growth. It describes how different plants require different amo..

Kidneys
Kidneys and Regulation of Water and Inorganic Ions

The kidneys are responsible for the regulation of water and inorganic ions. Read this tutorial to learn about the differ..