GENOMIC ANALYSIS OF VACCINE-DERIVED POLIOVIRUS STRAINS IN IMMUNOCOMPROMISED POPULATIONS

Abstract

Objective: We investigated the emergence, genomic characteristics, and transmission dynamics of vaccine‑derived poliovirus (VDPV) strains among immunocompromised individuals treated at a tertiary hospital in Punjab, Pakistan. Our goal was to identify genomic patterns associated with prolonged infection and potential viral adaptation.

Methods: This retrospective case study examined clinical, immunological, and genomic data from 30 immunocompromised patients who demonstrated prolonged poliovirus shedding over 24 months. Stool samples were collected at multiple time points and analyzed using whole‑genome sequencing and phylogenetic analysis. We compared the resultant sequences to the Sabin vaccine strain references and global VDPV databases. Demographic and clinical variables were evaluated to determine correlations with viral evolution.

Study Type: Case Study

Results: We observed substantial genomic divergence from Sabin vaccine strains across cases, with multiple isolates exhibiting ≥1% nucleotide changes in the VP1 region—a threshold consistent with circulating VDPV classification. Immunocompromised patients with profound B‑cell dysfunction exhibited the highest rates of intra‑host viral evolution. Phylogenetic reconstruction identified distinct clusters, indicating both independent evolution and evidence of limited local transmission.

Conclusion: The study revealed that immunocompromised populations served as reservoirs for prolonged VDPV replication and genomic diversification. Our findings underscored the need for enhanced surveillance and targeted immunization strategies in clinical settings with high prevalence of immunosuppression.