POST-POLIO RESEARCH UPDATE

Frederick M. Maynard, MD

Two new clinical research studies (references below) were recently published by a group of Italian investigators led by Dr. Antonio Toniolo, who has previously received funding from PHI’s Research Fund. Taken together, they offer hope for how to better identify those individuals with post-polio syndrome (PPS) who may benefit from treatments thought to improve the immune system’s ability to fight chronic viral infection.

STUDY 1: Low‑grade persistent poliovirus infection in long‑term polio survivors diagnosed with post‑polio syndrome: diagnostic and clinical implications1

Methods: White blood cells (WBCs) 

were isolated from blood samples taken from 96 subjects diagnosed with PPS according to the European Federation of Neurological Societies’ criteria, as well as from 26 stable paralytic polio survivors, 57 family members and 72 non-polio control group participants. The WBC samples then underwent an innovative procedure for identifying low-grade viral infection. The procedure includes culturing the WBCs with poliovirus (PV)-susceptible human cell lines and then extracting ribonucleic acid (RNA, a genetic material) samples that are next subjected to Reverse Transcriptase-PCR (Polymere Chain Reaction) in order to obtain sufficient RNA amounts for identification and analysis.

Results: PV genomes and proteins were found in 87% of subjects diagnosed with PPS compared to only 12% of 26 stable paralytic polio survivors, 3.5% of family member controls, and 0% of 72 other non-polio control groups. It also found high concordance of positive findings between results using WBCs or using CSF (cerebrospinal fluid), muscle tissue, or colon tissue samples from some PPS subjects for human cell line culturing and processing.

Discussion: These findings suggest persistent low-grade infection can persist for 50 years or more after Acute Paralytic Polio and that CSF, muscle, and/or intestinal tissue are the likely reservoirs for PV. Low detection rates among family members suggests minimal transferability of the PV genomes, many of which appeared to be mutated variants of either wild or vaccine-associated strains of PV. Viral genome replication rates were also shown to be very low.

The study’s results also suggest that a test for the presence of PV genomes in blood samples could become a feasible and useful diagnostic tool for prediction of which polio survivors were at greatest risk of PPS. Results also strongly support ongoing efforts to find effective anti-viral treatments, such as immunotherapies to slow or stop progressive PPS symptoms.

STUDY 2: Post-Polio Syndrome: Impact of Humoral Immune Deficiencies, Poliovirus Neutralizing Antibodies, Vitamin D Deficiency2

Based on blood sample analyses, 80 PPS subjects, as well as 40 family members, were shown to have significantly reduced levels of IgG (Immunoglobulin G), IgA, and IgG subclasses compared to non-polio controls.

Mean serum Vitamin D levels were also found to be significantly reduced in PPS subjects compared to non-polio controls, while the mean Vitamin D levels of the PPS family member group was intermediate between the PPS group and control group.

Conclusions

These studies’ overall findings suggest genetic, immunological, and nutritional factors may all increase susceptibility to the pathogenic effects of PV. Findings additionally highlight the complex relationships between immune status and long-term health of aging polio survivors.

References

  1. Toniolo A, Genoni A, Maccari G, Chumakov K, Basolo F, Bono G, Mauri M, Molteni F, Arrondini L, Bertolasi L, Monaco S. Low-grade persistent poliovirus infection in long-term polio survivors diagnosed with post-polio syndrome: diagnostic and clinical implications. J Neurol. 2025 Sep 6;272(9):617.
  2. Toniolo A, Chumakov K, Federico G, Maccari G, Genoni A, Saba A, Nauti A, Bono G, Molteni F, Monaco S. Post-Polio Syndrome: Impact of Humoral Immune Deficiencies, Poliovirus Neutralizing Antibodies, Vitamin D Deficiency. Vaccines (Basel). 2025 Sep 2;13(9):939.