What is the reassortment of influenza?
Reassortment is the process by which influenza viruses swap gene segments. This genetic exchange is possible due to the segmented nature of the viral genome and occurs when two differing influenza viruses co-infect a cell.
What are the consequences of genome reassortment on influenza virulence?
As summarized above, IAVs are genetically diverse and circulate within a diverse range of host species. Under these conditions, reassortment can result in rapid viral evolution, potentially contributing to epidemics, pandemics and cross-species transfers of the virus.
What is the host of the influenza virus?
There are four types of influenza (flu) viruses: A, B, C and D. Wild aquatic birds, including gulls, terns, and shorebirds, and wild waterfowl, such as ducks, geese and swans are considered reservoirs (hosts) for avian influenza A viruses.
What is the pathogenesis of the influenza virus?
The primary mechanism of influenza pathophysiology is a result of lung inflammation and compromise caused by direct viral infection of the respiratory epithelium, combined with the effects of lung inflammation caused by immune responses recruited to handle the spreading virus (Table 1).
What is genetic reassortment?
Genetic reassortment, the mixing of genes between two organisms to make a new genetic sequence known as a recombinant, is a powerful mechanism for evolution and adaptation. Sexual reproduction genetically recombines the genes of each parent. Each human is a recombinant of the parents’ genes.
What is genomic reassortment?
Reassortment is exclusively seen in viruses with a segmented genome. It is defined as the exchange of intact genes within the entire segment, which occurs during coinfection.
What is genome reassortment?
Reassortment is another form of genetic exchange that can occur in segmented viruses—viruses that have their genome split into multiple segments. Reassortment only occurs when multiple viruses co-infect the same cell, and replicate their progeny segments in the same cytoplasm.
How does influenza enter the host?
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 acidic environment of the endosomes, the virus changes shape and fuses its envelope with the endosomal membrane.
What is the host range of a virus?
Host range, defined as the number of host species used by a pathogen, is a simple metric that is central to understanding pathogen epidemiology and pathogenicity. Host range conditions the transmission dynamics and survival of pathogens and is predicted to be a major factor in their evolution.
What are the virulence factors of influenza?
A major virulence determinant in influenza virus is a multi-basic cleavage site within HA. Cleavage of the HA precursor, HA0, into HA1 and HA2 exposes the amino terminus of HA2 containing the fusion peptide, allowing for virus envelope fusion with a host endosomal membrane.
What is the structure of influenza virus?
The structure of the influenza virus (see Figure 1) is somewhat variable, but the virion particles are usually spherical or ovoid in shape and 80 to 120 nanometers in diameter. Sometimes filamentous forms of the virus occur as well, and are more common among some influenza strains than others.
What is viral genetic reassortment?
Virus reassortment, or simply reassortment, is a process of genetic recombination that is exclusive to segmented RNA viruses in which co-infection of a host cell with multiple viruses may result in the shuffling of gene segments to generate progeny viruses with novel genome combinations (Fig 1A) [1].