The purpose of this study was to obtain normal hearing thresholds for an ER-3A insert earphone as a contribution for future standardization and for comparison with previous studies and interim ANSI and ISO insert earphone reference equivalent threshold sound pressure levels (RETSPLs). Hearing thresholds were obtained on each ear of 48 normal-hearing subjects from 125 to 8000 Hz using ER-3A and ...

Influenza virus penetrates cells by fusion of viral and endosomal membranes catalyzed by the viral hemagglutinin (HA). Structures of the initial and final states of the HA trimer define the fusion endpoints, but do not specify intermediates. We have characterized these transitions by analyzing low-pH-induced fusion kinetics of individual virions and validated the analysis by computer simulation...

Since the 1918 influenza A virus (IAV) pandemic, H1N1 viruses have circulated in human populations. The hemagglutinin (HA) of IAV determines viral antigenicity and often undergoes N-linked glycosylation (NLG) at several sites. Interestingly, structural analysis of the 1918 and 2009 H1N1 pandemic viruses revealed antigenic similarities attributable to the conserved epitopes and the NLG statuses ...

Influenza virus contains two highly variable envelope glycoproteins, hemagglutinin (HA) and neuraminidase (NA). The structure and properties of HA, which is responsible for binding the virus to the cell that is being infected, change significantly when the virus is transmitted from avian or swine species to humans. Previously we identified much smaller human individual evolutionary amino acid m...

Serum and nasal wash specimens from 13 human volunteers undergoing experimental secondary infection with influenza A/Peking/2/79 (H3N2) wild-type virus were examined for the molecular form and subclass distribution of immunoglobulin A (IgA) antibodies to the viral hemagglutinin (HA). Nasal IgA antibodies were polymeric and did not bind radiolabeled secretory component, indicating that they were...

We have constructed virus-like particles (VLPs) harboring hemagglutinin (HA), neuraminidase (NA), matrix protein 1 (M1) ,and proton channel protein (M2) using baculovirus as a vector in the SF9 insect cell. The size of the expressed VLP was estimated to be ~100 nm by light scattering experiment and transmission electron microscopy. Recognition of HA on the VLP surface by the HA2-specific monocl...

Continual mutations to the hemagglutinin (HA) gene of influenza A virus generate novel antigenic strains that cause annual epidemics. Using a database of 560 viral RNA sequences, we study the structure and tempo of HA evolution over the past two decades. We detect a critical length scale, in amino acid space, at which HA sequences aggregate into clusters, or swarms. We investigate the spatio-te...

Influenza hemagglutinin (HA) is the primary target of the humoral response during infection/vaccination. Current influenza vaccines typically fail to elicit/boost broadly neutralizing antibodies (bnAbs), thereby limiting their efficacy. Although several bnAbs bind to the conserved stem domain of HA, focusing the immune response to this conserved stem in the presence of the immunodominant, varia...

Influenza hemagglutinin (HA) undergoes a conformational change that induces viral fusion with the cellular membrane. The structure of HA in the fusogenic state is unknown. We have identified a sequence in HA that has a high propensity for forming a coiled coil. Surprisingly, this sequence corresponds to a loop region in the X-ray structure of native HA: the loop is followed by a three-stranded,...