Streptococcus pyogenes Colonization in Children Aged 24–59 Months in the Gambia: Impact of Live Attenuated Influenza Vaccine and Associated Serological Responses

Abstract

Background Immunity to Streptococcus pyogenes in high burden settings is poorly understood. We explored S. pyogenes nasopharyngeal colonization after intranasal live attenuated influenza vaccine (LAIV) among Gambian children aged 24-59 months, and resulting serological response to 7 antigens. Methods A post-hoc analysis was performed in 320 children randomized to receive LAIV at baseline (LAIV group) or not (control). S. pyogenes colonization was determined by quantitative Polymerase Chain Reaction (qPCR) on nasopharyngeal swabs from baseline (D0), day 7 (D7) and day 21 (D21). Anti-streptococcal IgG was quantified, including a subset with paired serum pre/post S. pyogenes acquisition. Results The point prevalence of S. pyogenes colonization ranged from 7-13%. In children negative at D0, S. pyogenes was detected at D7 or D21 in 18% of LAIV group and 11% of control group participants (p=0.12). The odds ratio (OR) for colonization over time was significantly increased in the LAIV group (D21 vs D0 OR 3.18, p=0.003) but not in the control group (OR 0.86, p=0.79). The highest IgG increases following asymptomatic colonization were seen for M1 and SpyCEP proteins. Conclusions Asymptomatic S. pyogenes colonization appears modestly increased by LAIV, and may be immunologically significant. LAIV could be used to study influenza-S. pyogenes interactions.

Streptococcus pyogenespharyngitis elicits diverse antibody responses to key vaccine antigens influenced by the imprint of past infections

“…Where serum IgG responses were produced, they were maintained for at least 3 months, which suggests that S. pyogenes pharyngeal infection can induce long-lived antibody secreting cells 52 , as serum antibodies would have waned substantially based on IgG serum half-life alone 53 . Overall, the post-challenge antibody responses described here add to recent longitudinal studies 12,15,51 undermining the historical conception of asymptomatic colonisation ('carriage') with S. pyogenes as immunologically inert.…”

“…Antibody responses in these compartments did not correlate in magnitude or antigen-specificity, strongly suggesting they are produced and regulated independently. Overall, individual antibody responses were highly variable, as in previous longitudinal cohort studies of children 12,15,51 . Whilst every tested antigen was immunogenic in at least one participant, serum IgG responses were predominantly raised against conserved antigens with a role in evading human immunity (e.g.…”

Molecular methods enhance the detection of pyoderma-related Streptococcus pyogenes and emm-type distribution in children

“…Bacterial loads were quantified using standard curves generated by eight 10-fold serial dilutions of extracted DNA from S. pyogenes reference strain H293, S. aureus strain SH1000 and linearised plasmid DNA containing the S. scabiei SSR5 microsatellite sequence [15,21]. Dilutions ranged from 10,000,000 to 1 genome copy per PCR reaction.…”

“…Previously described S. pyogenes ( speB gene), S. aureus ( nuc gene), and S. scabiei (SSR5 microsatellite) PCR assays were integrated to establish a multiplex qPCR (Luna Universal Probe qPCR Master Mix (New England Biolabs) and primers and probes as outlined in Supplementary table 1 ) [15,21–23]. Nuclease-free water replicates were included as PCR negative controls.…”