An invasive Haemophilus influenzae serotype b infection in an Anglo-Saxon juvenile Plague victim. An invasive Haemophilus influenzae serotype b infection in an Anglo-Saxon juvenile Plague victim

With the continuous increase of large-scale shotgun sequencing projects in ancient DNA research, our understanding of past diversity of microbial pathogens keeps expanding and with it our ability to detect co-infections. In this study, we describe a full Haemophilus influenzae serotype b (Hib) genome isolated from a tooth of a six-years-old Anglo-Saxon plague victim (500-650 AD, Edix-Hill, England) showing signs of infection on it’s lower limbs and cranium, hinting at an invasive case of Hib. The human pathogen was the main cause of bacterial meningitis in children and one of the leading causes of worldwide childhood mortality prior to the introduction of a vaccine in the late 1980s. Our study presents the earliest genomic evidence for H. influenzae and points to the potential presence of larger genomic diversity in the phylogenetic division II serotype b clade in the past. Our findings further show that our Hib genome has a distinct virulence profile and allow first insights into the evolutionary history of this major human pathogen. Additionally to a full Hib genome we were also able to assemble a partial Yersinia pestis genome, which could be identical to previously published First Plague Pandemic genomes of Edix-Hill. The identification of both pathogens in a juvenile individual opens questions on the effect of plague in immunocompromised individuals and supports the assumption that Hib was already affecting juvenile populations in the 6th century AD.