What are the most important factors that determine influenza virus transmission to humans? Whether an influenza A virus will be transmitted from birds to humans primarily depends on two factors: the nature of the exposure to infected birds or their products and the susceptibility to infection with the influenza virus concerned. Initially, it was speculated […]
How are influenza viruses transmited from animals to humans? Many different animals, including birds such as ducks, geese, gulls and domestic poultry, and mammals such as pigs, whales, horses, dogs and seals, can be infected with influenza viruses. Remarkably, however, certain subtypes of influenza are solely or predominantly found in certain animal species. Birds, of […]
The deadliness of an influenza virus mainly depends on its ability to efficiently suppress the innate immune system, thereby allowing high levels of virus replication. This is more likely to occur with pandemic influenza where the individual has not been exposed to the new virus subtype before and must rely on the innate immune response […]
When the influenza virus infects the cells of the respiratory tract, both innate and adaptive immune responses are stimulated. The innate immune response develops very quickly and controls virus replication during the early stages of infection. The cytokines produced during this early phase in turn facilitate the activation of antigen-specific adaptive immune mechanisms. Adaptive immune […]
How are influenza viruses transmited from human to human? Seasonal and pandemic influenza are highly contagious diseases and are spread primarily by coughing and sneezing. When they sneeze, people release tiny droplets of fluid into the air. Those tiny droplets can fly up to 1 metre and infect persons nearby by reaching susceptible cells of […]
In humans, the primary targets for influenza viruses are the epithelial cells in the airways and lungs. The viral HA binds to sialic acid residues on glycoproteins or glycolipids on the cell surface. The act of binding draws the virus into the cell membrane. The virus shell fuses with the cell membrane and moves through […]
Morphology and structure The influenza virus belongs to the RNA viruses and comes from the family of Orthomyxoviridae. It is usually spherical in shape with a diameter of 80-120 nm. There are 3 distinct types of influenza virus: A, B and C. The genome consists of 8 (type A and B viruses) or 7 (type […]