Phage ImmunoPrecipitation Sequencing (PhIP-Seq) is a high throughput serological technology that is revolutionizing the manner in which we track antibody profiles. In this review, we mainly focus on its application to viral infectious diseases. Through the pull-down of patient antibodies using peptide-tile-expressing T7 bacteriophages and detection using next-generation sequencing (NGS), PhIP-Seq allows the determination of antibody repertoires against peptide targets from hundreds of proteins and pathogens. It differs from conventional serological techniques in that PhIP-Seq does not require protein expression and purification. It also allows for the testing of many samples against the whole virome. PhIP-Seq has been successfully applied in many infectious disease investigations concerning seroprevalence, risk factors, time trends, etiology of disease, vaccinology, and emerging pathogens. Despite the inherent limitations of this technology, we foresee the future expansion of PhIP-Seq in both investigative studies and tracking of current, emerging, and novel viruses. Following the review of PhIP-Seq technology, its limitations, and applications, we recommend that PhIP-Seq be integrated into national surveillance programs and be used in conjunction with molecular techniques to support both One Health and pandemic preparedness efforts.

Identifying individuals at high risk of infection is critical to guiding interventions during infectious disease outbreaks. Network centrality can characterize infection risk, but its utility varies across pathogens and social systems. We used equivalence-based blockmodeling to identify social-epidemiological roles associated with viral exposure among 1,297 adults in northeast Madagascar. Roles were determined based on social networks derived from reported shared free time and exchanges of food and farmwork. We identified three distinct role categories, including individuals with many reciprocated social ties (Popular), individuals who sent many ties with few reciprocated (Hangers-On), and individuals who had few connections (Periphery). To assess whether the role categories covaried with viral exposure, we performed Phage ImmunoPrecipitation Sequencing with VirScan using dried blood spot samples to determine exposure to 337 virus species and subtypes. Individuals in the Popular ( ß [95% CI]: 0.29 [−0.06-0.63]) and Hangers-On ( ß [95% CI]: 0.36 [0.12-0.60]) role categories had greater viral exposure than individuals in the Periphery role category. Roles performed better at predicting exposure than single measures of centrality. Equivalence-based blockmodeling extends the utility of network centrality for characterizing infection risk and provides new insights into how social roles relate to both pathogen exposure and susceptibility to infection.