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Correlation between plaque size and genetic variation of type 3 poliovirus from a vaccinate
Abstract:
Vaccine strain derivatives could be serially isolated from the feces of a healthy infant for about 30 days after the second administration of a trivalent poliovirus vaccine. These were all identified as poliovirus type 3, and no other types were detected. The titer in feces increased gradually until day 19, when it reached a maximum, after which it decreased. The plaque size altered roughly in parallel with the changes in the titer. On day 11 it began to increase, becoming the highest abruptly on day 15, and then fell again. Oligonucleotide mapping analysis of RNAs of isolated viruses showed that the samples from days 1 and 11 exhibited the same patterns as those shown by the vaccine strain RNA. However, on day 15 many of the preexisting spots had decreased, and new ones appeared. On day 27, the pattern was again similar to that of the original virus, rather than that of the day-15 virus. A nonmetric distance scaling and cluster analysis suggested that all the strains were derived from the same origin and that the polioviruses on days 1, 11, 21, and 27 had closer relationships, but the poliovirus on day 15 was different.
Insights
Polio vaccine virus was detected in infant feces for 30 days. Genetic analysis revealed distinct viral changes on day 15, suggesting a unique viral evolution during this period.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Poliovirus vaccines are crucial for eradicating poliomyelitis.
- Understanding the behavior and genetic stability of vaccine strains in vivo is essential for public health.
Purpose of the Study:
- To investigate the shedding and genetic evolution of poliovirus vaccine strains in a healthy infant.
- To characterize temporal changes in poliovirus type 3 derived from a trivalent vaccine.
Main Methods:
- Serial fecal sample collection and virus isolation from an infant post-vaccination.
- Plaque size analysis and RNA oligonucleotide mapping of isolated poliovirus strains.
- Nonmetric distance scaling and cluster analysis for phylogenetic relationships.
Main Results:
- Vaccine-derived poliovirus type 3 was isolated for approximately 30 days.
- Viral titer and plaque size peaked around day 19.
- Oligonucleotide mapping revealed distinct genetic changes on day 15, differentiating it from earlier and later strains.
Conclusions:
- The poliovirus vaccine strain persisted and shed for an extended period.
- Significant genetic divergence of the poliovirus occurred around day 15 post-vaccination.
- These findings highlight the dynamic genetic evolution of vaccine strains within a host.