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Mucosal immunity to poliovirus measured in infants' stool
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In an analysis of the Fighting Infectious Diseases in Emerging Countries trial in Latin America, researchers reported mucosal type 2-specific antibodies could be measured in the stool of infants who received oral poliovirus vaccine type 2.
“Our novel data have direct and immediate global policy implications and point to the unique ability of [trivalent oral poliovirus vaccine (tOPV)] to stimulate mucosal immunity, the dissociation of serum and mucosal antibody responses, and the crucial role of mucosal immunity in preventing infection on [a monovalent oral poliovirus (mOPV)] type 2 challenge,” Peter F. Wright, MD, of the department of pediatrics, Geisel School of Medicine at Dartmouth College, and colleagues wrote. “Our data will help national, regional and global policymakers to develop public health strategies to achieve and sustain polio eradication in the near term and long term.”
Researchers from the Fighting Infectious Diseases in Emerging Countries (FIDEC) trial enrolled infants from Colombia, the Dominican Republic, Guatemala and Panama and randomly assigned them to bivalent oral poliovirus vaccine or inactivated poliovirus vaccine, then a challenge with monovalent type 2 oral poliovirus vaccine at age 18 weeks, according to Wright and colleagues. The researchers collected infants’ stool and tested it for mucosal type 2 neutralization and poliovirus-type–specific immunoglobulin A in the current analysis.
Wright and colleagues examined three groups: the bivalent vaccine control group (n = 85), the trivalent-attenuated vaccine control group (n = 38) and the bivalent-inactivated vaccine group (n = 87). According to their findings, 1 week after challenge 5% of the infants in the trivalent vaccine group demonstrated viral shedding, while viral shedding was reported in 69% of those in the bivalent vaccine group (P < .0001), and 61% of the combination bivalent-inactivated vaccine group (P < .0001).
Mucosal type 2 neutralization and concentrations of type 2-specific IgA were greater among infants in the trivalent vaccine group, according to the investigators. They also reported an inverse relationship between virus shedding and serum type 2 neutralization (P < .0001) and mucosal type 2 neutralization at challenge (P < .0001).
In an accompanying editorial, Edward P.K. Parker, MSc, and Nicholas C. Grassly, PhD, both of the department of infectious disease epidemiology at Imperial College London, wrote that the study “draws attention to one of the major obstacles currently facing the polio endgame: the deficits in serotype 2 mucosal immunity after a mixed schedule of [bivalent oral poliovirus and inactivated poliovirus vaccines].
“Comprehensive surveillance of children with acute flaccid paralysis and environmental samples is undoubtedly crucial to the success of the polio endgame,” Parker and Grassly wrote. – by Andy Polhamus
Disclosure: The researchers report no relevant financial disclosures.
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