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#medical microbiology

14 public questions tagged with this topic.

Vaccine

Inactivated vaccines usually require:

Inactivated vaccines usually require multiple doses and periodic boosters to achieve and sustain protective immunity because non replicating antigen provides transient immune stimulation. Initial dose primes naive B cells in draining lymph nodes producing low affinity IgM and modest IgG, small memory pool, titer often below correlate of protection threshold. Second dose administered 4-8 weeks later triggers anamnestic response with larger germinal center reaction, extensive somatic hypermutation in dark zone mediated by activation induced cytidine deaminase, affinity maturation, isotype class

Ref: Plotkin Why inactivated needs multiple doses; WHO Immunization schedule; Amanna Duration.

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Vaccine

Which vaccine is administered orally?

Oral polio vaccine OPV is classical example administered via oral route as drops rather than injection. Formulated by Albert Sabin in 1957 containing live attenuated poliovirus types 1,2,3 propagated in primary monkey kidney cells, stabilized with MgCl2, sucrose, buffered. Oral delivery mimics natural fecal oral transmission of wild poliovirus. Attenuated virus replicates in M cells of Peyer's patches, gut associated lymphoid tissue generating strong intestinal secretory IgA preventing colonization and transmission, plus systemic IgG and intestinal CD4 T cells. Advantages include easy administ

Ref: WHO OPV oral vaccine; Sabin J Exp Med 1957; Plotkin Polio oral route.

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Vaccine

A major advantage of live attenuated vaccines is:

Major advantage of live attenuated vaccines lies in induction of strong, durable, broad immunity closely mimicking natural infection without causing disease in immunocompetent hosts. Limited replication provides continuous antigen synthesis over days to weeks prolonging immune exposure far beyond bolus injection of killed antigen, sustaining germinal center reactions, affinity maturation and generation of long lived plasma cells producing high affinity IgG persisting decades and memory B cells. Activation of cytosolic innate sensors RIG-I, MDA5, STING by replicating nucleic acids induces robus

Ref: Amanna Nature Medicine 2007 Live vaccine long immunity; Plotkin Advantage robust; Pulendran.

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