Biology subjects

Mao, K. J.

Publications and source records attributed to Mao, K. J..

4 recordsLinked to original sources

bioRxiv2025

Evolution of antibody cross-reactivity to influenza H5N1 neuraminidase from an N2-specific germline

The ongoing spread of highly pathogenic avian influenza H5N1 clade 2.3.4.4b virus in animals and its occasional spillover to humans have raised concerns about a potential H5N1 pandemic. Although recent studies have shown that pre-existing human antibodies can recognize H5N1 neuraminidase, the molecular basis of how this cross-reactivity develops remains poorly understood. In this study, we used a phage display antibody library derived from 245 healthy donors to isolate an antibody, HB420, that cross-reacts with neuraminidases of human H3N2 and avian H5N1 clade 2.3.4.4b viruses and confers protection in vivo. Cryo-EM analysis reveals that HB420 targets the neuraminidase active site by mimicking sialic acid binding through a single Asp residue. Furthermore, the inferred germline of HB420 is N2-specific but acquires cross-reactivity to H5N1 neuraminidase through somatic hypermutation. Overall, our findings provide insights into how neuraminidase antibody evolves breadth, which has important implications for the development of broadly protective influenza vaccines.

immunology↗

bioRxiv2024

Deep mutational scanning of influenza A virus NEP reveals pleiotropic mutations in its N-terminal domain

The influenza A virus nuclear export protein (NEP) is a multifunctional protein that is essential for the viral life cycle and has very high sequence conservation. However, since the open reading frame of NEP largely overlaps with that of another influenza viral protein, non-structural protein 1, it is difficult to infer the functional constraints of NEP based on sequence conservation analysis. Besides, the N-terminal of NEP is structurally disordered, which further complicates the understanding of its function. Here, we systematically measured the replication fitness effects of >1,800 mutations of NEP. Our results show that the N-terminal domain has high mutational tolerance. Additional experiments demonstrate that N-terminal domain mutations pleiotropically affect viral transcription and replication dynamics, host cellular responses, and mammalian adaptation of avian influenza virus. Overall, our study not only advances the functional understanding of NEP, but also provides insights into its evolutionary constraints.

cell biology↗

bioRxiv2024

Differential antigenic imprinting effects between influenza H1N1 hemagglutinin and neuraminidase in a mouse model

Understanding how immune history influences influenza immunity is essential for developing effective vaccines and therapeutic strategies. This study investigates the antigenic imprinting of influenza hemagglutinin (HA) and neuraminidase (NA) using a mouse model with sequential infection by four seasonal H1N1 strains. Our findings reveal that, among pre-2009 H1N1 strains, the extent of infection history correlates with the restriction of antibody responses to antigenically drifted HA, but not NA. This suggests the mouse model failed to recapitulate NA imprinting in humans, likely due to the difference in NA immunodominance hierarchy between humans and mice. Nevertheless, pre-existing antibodies induced by infection with pre-2009 influenza virus impeded both functional HA and NA antibody responses against a 2009 pandemic H1N1 strain. Overall, this study provides insights into antigenic imprinting for influenza virus, as well as the limitations of using mouse models for studying antigenic imprinting. ImportanceInfluenza viruses continue to pose a significant threat to human health, with vaccine effectiveness being a persistent concern. One important factor is the individual immune history can influence subsequent antibody responses. While many studies have focused on how pre-existing antibodies influence the induction of anti-HA antibodies after influenza virus infections or vaccinations, the impact on anti-NA antibodies has been less extensively investigated. In this study, using a mouse model, we highlighted within the pre-2009 H1N1 strains, a greater extent of immune history negatively affected anti-HA antibodies but positively influenced anti-NA antibody responses. However, for the 2009 pandemic H1N1 strain, which underwent with antigenic shift, both anti-HA and anti-NA antibody responses have been impeded by the antibodies induced by pre-2009 H1N1 virus infection. These findings have important implications for enhancing our understanding of antigenic imprinting on anti-HA and anti-NA antibody response and for developing more effective vaccination strategies.

immunology↗

bioRxiv2023

Stringent and complex sequence constraints of an IGHV1-69 broadly neutralizing antibody to influenza HA stem

IGHV1-69 is frequently utilized by broadly neutralizing influenza antibodies to the hemagglutinin (HA) stem. These IGHV1-69 HA stem antibodies have diverse complementarity-determining region (CDR) H3 sequences. Besides, their light chains have minimal to no contact with the epitope. Consequently, sequence determinants that confer IGHV1-69 antibodies with HA stem specificity remain largely elusive. Using high-throughput experiments, this study revealed the importance of light chain sequence for the IGHV1-69 HA stem antibody CR9114, which is the broadest influenza antibody known to date. Moreover, we demonstrated that the CDR H3 sequences from many other IGHV1-69 antibodies, including those to HA stem, were incompatible with CR9114. Along with mutagenesis and structural analysis, our results indicate that light chain and CDR H3 sequences coordinately determine the HA stem specificity of IGHV1-69 antibodies. Overall, this work provides molecular insights into broadly neutralizing antibody responses to influenza virus, which have important implications for universal influenza vaccine development.

molecular biology↗