This is the main reason why seasonal influenza vaccines are updated frequently, to maintain protection in risk groups against currently circulating strains (Arinaminpathy & Grenfell, 2010). When a type A virus undergoes both kinds of changes, it is capable of evading host immunity, with profound implications for epidemiology and control. Since the late nineteenth century, four occurrences of antigenic shift have led to major influenza pandemics.Īlthough influenza viruses constantly and gradually change by antigenic drift, antigenic shift happens only occasionally. An antigenic shift can lead to a worldwide pandemic if the virus is efficiently transmitted from person to person.Īn example of a “shift” occurred in the spring of 2009, when a novel H1N1 virus with a new combination of genes (from American pigs, Eurasian pigs, birds, and humans) emerged in people and quickly spread, causing a pandemic. What do you mean by antigenic drift Antigenic drift is the gradual change in viral genetic makeup. Source: Griffinstorm, Wikipedia Commons.Īntigenic shift results in a new influenza A subtype that is so different from previous subtypes in humans that most people do not have immunity to the new virus. Antigenic shifts are the type of viral mutations that can cause pandemics and epidemics. Like this lightning storm near New Boston, Texas, antigenic shift involves major, abrupt changes in surface antigens (HA or NA). Flu viruses can change in two different waysantigenic drift and antigenic shift. Changes due to antigenic drift can nevertheless accumulate over time, straining the ability of a person’s immune system to recognize the new virus. These changes produce new viral strains that are fairly closely related to one another and may be recognized by the immune system (sometimes called “cross-protection”). Describe the types of lab assays available for detecting an infection with SARS-CoV-2 or IAV and IBV, as well as tests used to monitor the health status of patients with COVID-19. meningitidis genetic background on the basis of DNA sequences of. Describe how antigenic drift and antigenic shift occur for IAV or IBV and SARS-CoV-2. Think of a small boat drifting across the ocean or clouds drifting across the sky. For serogroup Y, antigenic shift occurred through amino acid. ![]() Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and. Antigenic Drift: Continual Small ChangesĪ ntigenic drift involves continual small changes or mutations to a virus’s surface antigens (HA or NA). Genetic drift describes random fluctuations in the numbers of gene variants in a population. Influenza type A viruses undergo both kinds of changes, while influenza type B and C viruses change only by the gradual process of antigenic drift. Viruses do this through evolutionary processes called antigenic drift and antigenic shift. To successfully infect a person, the influenza virus must develop ways to evade a person’s immune system. ![]() Please click here to view the current ATrain course listings. ![]() There is no replacement course at this time.
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