Currently, the phage display technology is probably one of the most mature animal-free alternatives to the hybridoma technology for developing antibodies. However, the performances of these two technologies have been rarely compared. To address this question, hybridoma and phage display approaches were used to generate antibodies against Zika virus (ZIKV) non-structural protein 1 (NS1), a biomarker of the acute phase of flavivirus infection that displays high sequence homology among flaviviruses. Phage display-derived antibodies showed enhanced specificity towards ZIKV recombinant NS1 (rNS1). Conversely, hybridoma-derived antibodies cross-reacted with other flavivirus rNS1. This likely reflects differences in selection strategies rather than in the intrinsic properties of the technologies. Despite the moderate binding affinity of paired antibodies obtained by phage display, a limit of detection of 25ng/mL was achieved in human serum spiked with ZIKV rNS1. This sensitivity dropped to 1ng/mL with antibodies obtained by mice immunization. Then, the high specificity of phage display-derived antibodies and sensitivity of hybridoma-derived antibodies were combined in a hybrid antibody format immunoassay. In this assay, a very specific phage display-derived antibody was used for capture and a hybridoma-derived antibody with a low dissociation rate constant (koff) was used for detection, maintaining sensitivity as low as 1ng/mL. This hybrid assay format also preserved high specificity when tested using serum samples from patients with acute Dengue fever that contain high levels of Dengue virus NS1. Our findings highlight the complementary strengths of both antibody generation strategies for the sensitive and specific detection of ZIKV NS1.

Bronchiolitis is an acute lower respiratory tract infection mainly affecting children under 24months, primarily caused by Respiratory Syncytial Virus (RSV). Interferons (IFNs), cytokines central to innate and adaptive immunity, are secreted in response to viral infections. In RSV bronchiolitis, Type I and III IFN Signatures modulate antiviral responses and impact disease severity. This study aimed to evaluate the correlation between Type I and III IFNs transcriptional signatures in blood and nasal swabs with clinical presentation. We analyzed transcription levels of Type I and III IFN Signatures using a PCR real-time TaqMan assay in blood and nasal swabs from children hospitalized for RSV bronchiolitis and from healthy controls (HC). Interferon score I was significantly higher in bronchiolitis patients at admission than at discharge and compared to HC, in both blood and nasal swabs (p<0.0001). A strong positive correlation for IFN score I between the two sample types was found (p<0.0001). Patients with severe disease (requiring intensive care) had lower IFN score I than those with milder disease, in both blood (p=0.0005) and nasal swabs (p=0.0078). IFN score III was down-regulated in bronchiolitis patients compared to HC in blood samples (p<0.0001), while in nasal swabs, this down-regulation was evident only at discharge (p<0.0001 vs admission; p=0.0546 vs HC). This study enhances understanding of IFN signature dynamics in RSV bronchiolitis, emphasizing the importance of sample type and signature specificity, and suggests their potential use as prognostic tools to improve patient management.