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Virus excretion and mutation by infants following primary vaccination with live oral poliovaccine from two sources
1National Institute for Biological Standards and Control, Potters Bar, Herts, U.K.
Abstract:
The excretion of virus by 30 children was followed over a period of 28 days after their first vaccination with live oral poliovaccine. The type 1 and type 2 strains were isolated at similar high frequencies throughout this period, while the type 3 strain was not excreted by most children after day 2 post vaccination. Mutations in the 5' non-coding region associated with the attenuated phenotype reverted most rapidly for type 3 and least rapidly for type 1. The data are consistent with different degrees of selection against the attenuating mutations in the three serotypes in the gut, but imply that reversion is required for prolonged excretion. The findings also provide a possible explanation for the reported distribution of the rarely occurring vaccine associated cases between recipients and contacts for the three serotypes. A statistically significant difference was not observed between vaccine from the two main suppliers to the UK market.
Insights
Live oral poliovaccine excretion varied by serotype in children. Type 3 poliovirus showed rapid reversion and limited excretion, unlike types 1 and 2, impacting vaccine-associated case distribution.
Area of Science:
- Virology
- Vaccinology
- Molecular biology
Background:
- Live oral poliovaccine (OPV) is crucial for polio eradication.
- Understanding poliovirus shedding dynamics post-vaccination is vital for disease control.
- Serotype-specific differences in OPV behavior may influence transmission and vaccine safety.
Purpose of the Study:
- To investigate the excretion patterns of poliovirus serotypes following live oral poliovaccine administration.
- To analyze the reversion of attenuating mutations in the 5' non-coding region for each serotype.
- To correlate excretion and reversion data with vaccine-associated disease risks.
Main Methods:
- Followed poliovirus excretion in 30 children for 28 days post-OPV vaccination.
- Isolated and quantified poliovirus serotypes (1, 2, and 3) from fecal samples.
- Sequenced the 5' non-coding region to identify mutations associated with attenuation and reversion.
Main Results:
- Type 1 and type 2 poliovirus were excreted frequently throughout the 28-day period.
- Type 3 poliovirus excretion was limited, with most children clearing the virus by day 2 post-vaccination.
- Reversion of attenuating mutations was fastest for type 3 and slowest for type 1, suggesting differential gut selection pressures.
Conclusions:
- Different poliovirus serotypes exhibit distinct excretion and mutation reversion profiles in the gut.
- Reversion of attenuating mutations appears necessary for prolonged poliovirus excretion.
- These findings may explain the serotype distribution in rare vaccine-associated paralytic poliomyelitis cases.