How contagious is type A flu? If you have the flu, you’re contagious from at least a day before you begin to experience symptoms up through five days after your symptoms begin. In more severe cases, you could be contagious for even longer after you begin experiencing symptoms.
how is the genome configured within influenza viruses?
The influenza viruses are characterized by segmented, negative-strand RNA genomes requiring an RNA-dependent RNA polymerase of viral origin for replication. The particular structure of the influenza virus genome and function of its viral proteins enable antigenic drift and antigenic shift.
Why does the influenza virus mutate so rapidly? Influenza viruses, like most other viruses, evolve fast because of high mutation rates and because of antigenic shift, so that there is a high number of different genotypes at any time. The match between vaccine and virus, however, needs to be close to perfect, in order to shield an organism from an infection.
is influenza A genetic disease?
IT MIGHT sound strange to suggest that flu is, in any sense, a hereditary illness. Classic inherited diseases, such as sickle-cell anaemia and cystic fibrosis, are caused by broken genes that come from a sufferer’s parents. Flu is caused by a virus.
What does the H and N mean in h1n1?
The “H” (hemagglutinin) and the “N” (neuraminidases) are both proteins that are found on the outer shell or envelope of the virus. Different viruses have different hemagglutinin and neuraminidase proteins.
is the influenza virus DNA or RNA?
Like all living things, influenza makes small errors—mutations—when it copies its genetic code during reproduction. But influenza lacks the ability to repair those errors, because it is an RNA virus; RNA, unlike DNA, lacks a self-correcting mechanism. As a result, influenza is not genetically stable.
How many types of flu are there?
What causes the influenza virus?
The flu is caused by influenza viruses that infect the nose, throat, and lungs. These viruses spread when people with flu cough, sneeze or talk, sending droplets with the virus into the air and potentially into the mouths or noses of people who are nearby.
Which influenza virus is the most responsible for flu season outbreaks?
Influenza A and B viruses are responsible for seasonal flu epidemics each year. Influenza viruses can change in two different ways—antigenic drift and antigenic shift.
How many types of influenza are there?
Types of flu virus There are actually four different types of influenza viruses: influenza A, B, C, and D. Influenza A and B are the two types of influenza that cause epidemic seasonal infections nearly every year. Influenza A can be found in many species, including humans, birds, and pigs.
What animals are reservoirs for influenza viruses?
More than 100 types of influenza A infect most species of birds, pigs, horses, dogs, and seals. Influenza B has also been reported in seals, and influenza C has been reported, though rarely, in pigs. Some of these influenza strains are species-specific.
How does influenza replicate its genome?
The influenza virus enters the host cell by having its hemagglutinin bind to the sialic acid found on glycoproteins or glycolipid receptors of the host. The cell then endocytoses the virus. In the host nucleus, the virus does primary transcription to produce necessary proteins for replication.
What type of nucleic acid does influenza have?
Influenza viruses are called (-) strand RNA viruses because of the polarity of the RNA that is carried in the virion. Other RNA viruses – such as poliovirus – are (+) strand RNA viruses, because their genomic RNA can be translated into protein immediately upon entering the cell.
Is Influenza an enveloped virus?
The influenza virion (as the infectious particle is called) is roughly spherical. It is an enveloped virus – that is, the outer layer is a lipid membrane which is taken from the host cell in which the virus multiplies. Within the interior of the virion are the viral RNAs – 8 of them for influenza A viruses.
What is the structure of influenza?
Structurally, the influenza virus is spherical in shape. It is covered in an envelope made of a lipid bilayer with spikes of glycoproteins called haemagglutinin and neuraminidase. These proteins enable the virus to effectively bind with a host cell.