As the world is approaching the eradication of wild poliovirus serotype 1, the last of the three wild types, the question of how to maintain a polio-free world becomes imminent. To mitigate the risk of sporadic vaccine-associated paralytic polio (VAPP) caused by oral polio vaccines (OPVs) that are routinely used in global immunization programs, the Polio Antivirals Initiative (PAI) was established in 2006. The primary goal of the PAI is to facilitate the discovery and development of antiviral drugs to stop the excretion of immunodeficiency-associated vaccine-derived poliovirus (iVDPV) in B cell-deficient individuals. This review summarizes the major progress that has been made in the development of safe and effective poliovirus antivirals and highlights the candidates that have shown promising results in vitro, in vivo, and in clinical trials.

Virus neutralization assays, widely used to detect and quantify antibodies induced by virus infection, are considered the gold standard for enterovirus serology testing. Conventional microneutralization assays have been used to assess enterovirus D68 (EV-D68) seroprevalence. While manual or automated 96-well assays are valuable, higher-density assays that increase throughput provide the opportunity to more efficiently screen large, population-based serology collections, as well as to test sample sets against multiple virus strains on the same plate or within the same run. Here, automation was implemented for bulk reagent dispensing, serial dilutions, and luminescence measurement to develop a 384-well enterovirus microneutralization assay that increases overall testing throughput, maintains the reproducibility of the standard 96-well assay, and reduces sample volume usage. EV-D68 strains Fermon, 14-18953, and 18-23087 were used to evaluate the automated 384-well microneutralization assay and compare to the conventional 96-well assay. Sensitivity and specificity were evaluated using pooled human sera and positive and negative control antisera. The Lower Limit of quantitation (LLOQ) was the same as for the 96-well assay and coefficients of variations (CV) of 7.35%, 5.97%, and 2.85% for the three EV-D68 strains respectively, were well below the typical goal of ≤ 20% CV for accuracy. Z-factor analysis yielded results of 0.694, 0.638, and 0.852, for the three EV-D68 strains respectively, indicating a high level of precision, reliability, and robustness. Intra-assay (7.25%) and inter-assay (7.12%) variability were well below 20% CV. Moreover, the 96-well and 384-well versions of the assay were highly concordant, with a 0.955 correlation coefficient in titers obtained for 144 sera tested. Validation of this automated 384-well microneutralization will support its use in large serology screens assessing the presence of EV-D68 neutralizing antibodies in human populations.

We report the complete genome sequences of four parechovirus-A3 (PeV-A3) isolates from Children’s Mercy Kansas City (CMKC), United States of America (USA): PeV-A3-MO-12-CMKC/CSF/MO/USA/2012 (isolated in 2012 from cerebrospinal fluid), PeV-A3-8C-CMKC/CSF/MO/USA/2022/ (isolated in 2022 from cerebrospinal fluid), PeV-A3-9C-CMKC/CSF/MO/USA/2022 (isolated in 2022 from cerebrospinal fluid), and PeV-A3-11B-CMKC/Blood/MO/USA/2022 (isolated in 2022 from blood). Sequence analysis revealed multiple mutations throughout the genome of the PeV-A3 isolates in comparison to the prototypic PeV-A3 A308/99 reference sequence (AB084913). Several unique amino acid changes were observed in the PeV-A3 isolates from 2022 that were absent in the PeV-A3 isolate from 2012. Phylogenetic analysis comparison determined that the sequenced PeV-A3 isolates from 2022 cluster together as a separate clade.