Variants of Streptococcus pneumoniae Serotype 14 from Papua New Guinea with the Potential to Be Mistyped and Escape Vaccine-Induced Protection
Sam Manna, Leena Spry, Ashleigh Wee-Hee, Belinda D. Ortika, Laura K. Boelsen, Steven Batinovic, Nadia Mazarakis, Rebecca Ford, Stephanie W. Lo, Stephen D. Bentley, Fiona M. Russell, Christopher C. Blyth, William Pomat, Steve Petrovski, Jason Hinds, Paul V. Licciardi, Catherine Satzke
Abstract
Pneumococcus is a pathogen of major public health importance. Current vaccines have limited valency, targeting a subset (up to 20) of the more than 100 capsule types (serotypes). Precise serotyping methods are therefore essential to avoid mistyping, which can reduce the accuracy of data used to inform decisions around vaccine introduction and/or maintenance of national vaccination programs. In this study, we examine a variant of serotype 14 (14-like), a virulent serotype present in all currently licensed vaccine formulations. Although these 14-like pneumococci no longer produce a serotype 14 capsule, widely used molecular methods can mistype them as serotype 14. Importantly, we show that 14-like pneumococci can evade opsonophagocytic killing mediated by vaccination. Despite the high accuracy of molecular methods for serotyping, our study reemphasizes their limitations. This is particularly relevant in situations where nonvaccine type pneumococci (e.g., the 14-likes in this study) could potentially be misidentified as a vaccine type (e.g., serotype 14).