Antigenic Shift And Drift Of Influenza Virus Pdf

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Antigenic drift is a kind of genetic variation in viruses, arising by the accumulation of mutations in the virus genes that code for virus-surface proteins that host antibodies recognize. This results in a new strain of virus particles that is not effectively inhibited by the antibodies that prevented infection by previous strains. This makes it easier for the changed virus to spread throughout a partially immune population.

Influenza Virus: Dealing with a Drifting and Shifting Pathogen

Surveillance data indicate that most circulating A H1N1 pdm09 influenza viruses have remained antigenically similar since they emerged in humans in However, antigenic drift is likely to occur in the future in response to increasing population immunity induced by infection or vaccination. In this study, sequential passaging of A H1N1 pdm09 virus by contact transmission through two independent series of suboptimally vaccinated ferrets resulted in selection of variant viruses with an amino acid substitution NK, H1 numbering without signal peptide; NK, H3 numbering without signal peptide; NK, H1 numbering from first methionine in a known antigenic site of the viral HA. In vitro , in a range of cell culture systems, the NK variant rapidly adapted, acquiring additional mutations in the viral HA that also potentially affected antigenic properties. The NK escape mutant was antigenically distinct from wildtype virus as shown by binding of HA-specific antibodies.

If the address matches an existing account you will receive an email with instructions to reset your password. If the address matches an existing account you will receive an email with instructions to retrieve your username. Numerous modern technological and scientific advances have changed the vaccine industry. However, nearly 70 years of influenza vaccine usage have passed without substantial changes in the underlying principles of the vaccine. The challenge of vaccinating against influenza lies in the constantly changing nature of the virus itself. Influenza viruses undergo antigenic evolution through antigenic drift and shift in their surface glycoproteins. This has forced frequent updates of vaccine antigens to ensure that the somewhat narrowly focused vaccine-induced immune responses defend against circulating strains.

How the Flu Virus Can Change: “Drift” and “Shift”

The changes associated with antigenic drift happen continually over time as the virus replicates. The small changes that occur from antigenic drift usually produce viruses that are closely related to one another, which can be illustrated by their location close together on a phylogenetic tree. Influenza viruses that are closely related to each other usually have similar antigenic properties. However, the small changes associated with antigenic drift can accumulate over time and result in viruses that are antigenically different further away on the phylogenetic tree. It is also possible for a single or small change in a particularly important location on the HA to result in antigenic drift.

Influenza Virus: Dealing with a Drifting and Shifting Pathogen

H5N1 avian influenza virus: an overview. Address for correspondence. Avian influenza virus H5N1 emerged in Hong Kong in , causing severe human disease. In recent years, several outbreaks have been reported in different parts of Asia, Europe and Africa, raising concerns of dissemination of a new and highly lethal influenza pandemic. Although H5N1 has not been capable of sustaining human-to-human transmission, the ability of the virus to undergo variation due to mutations and reassortment, clearly poses the possibility of viral adaptation to the human species.

The relationship between influenza antigenic drift and vaccination lies at the intersection of evolutionary biology and public health, and it must be viewed and analyzed in both contexts simultaneously. In this paper, I review what is known about the effects of antigenic drift on vaccination and the effects of vaccination on antigenic drift, and I suggest some simple ways to detect the presence of antigenic drift in seasonal influenza data. If antigenic drift occurs on the time scale of a single influenza season, it may be associated with the presence of herd immunity at the beginning of the season and may indicate a need to monitor for vaccine updates at the end of the season. The relationship between antigenic drift and vaccination must also be viewed in the context of the global circulation of influenza strains and the seeding of local and regional epidemics.

Antigenic drift

The Transmission of Epidemic Influenza pp Cite as. A major change in the antigenicity of influenza A virus in presented a problem to the scientists who were studying the virus.

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4 Response
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  2. Grazian V.

    Through modeling, the lesson presented in this article helps students understand how the influenza virus (or flu) evolves and how flu vaccines are.

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