Hang Xie

CpG Oligodeoxynucleotides Adsorbed onto Polylactide-Co-Glycolide Microparticles Improve the Immunogenicity and Protective Activity of the Licensed Anthrax Vaccine

ABSTRACT To reduce the biothreat posed by anthrax, efforts are under way to improve the protection afforded by vaccination. This work examines the ability of immunostimulatory CpG oligodeoxynucleotides (ODN) adsorbed onto cationic polylactide-co-glycolide (PLG) microparticles (CpG ODN-PLG) to accelerate and boost the protective immunity elicited by Anthrax Vaccine Adsorbed (AVA, the licensed human anthrax vaccine). The results indicate that coadministering CpG ODN-PLG with AVA induces a stronger and faster immunoglobulin G response against the protective antigen of anthrax than AVA alone. Immunized mice were protected from lethal anthrax challenge within 1 week of vaccination with CpG ODN-PLG plus AVA, with the level of protection correlating with serum immunoglobulin G anti-protective antigen titers.

H3N2 Mismatch of 2014–15 Northern Hemisphere Influenza Vaccines and Head-to-head Comparison between Human and Ferret Antisera derived Antigenic Maps

The poor performance of 2014–15 Northern Hemisphere (NH) influenza vaccines was attributed to mismatched H3N2 component with circulating epidemic strains. Using human serum samples collected from 2009–10, 2010–11 and 2014–15 NH influenza vaccine trials, we assessed their cross-reactive hemagglutination inhibition (HAI) antibody responses against recent H3 epidemic isolates. All three populations (children, adults, and older adults) vaccinated with the 2014–15 NH egg- or cell-based vaccine, showed >50% reduction in HAI post-vaccination geometric mean titers against epidemic H3 isolates from those against egg-grown H3 vaccine strain A/Texas/50/2012 (TX/12e). The 2014–15 NH vaccines, regardless of production type, failed to further extend HAI cross-reactivity against H3 epidemic strains from previous seasonal vaccines. Head-to-head comparison between ferret and human antisera derived antigenic maps revealed different antigenic patterns among representative egg- and cell-grown H3 viruses characterized. Molecular modeling indicated that the mutations of epidemic H3 strains were mainly located in antibody-binding sites A and B as compared with TX/12e. To improve vaccine strain selection, human serologic testing on vaccination-induced cross-reactivity need be emphasized along with virus antigenic characterization by ferret model.

Cross-Neutralizing Antibodies to Pandemic 2009 H1N1 and Recent Seasonal H1N1 Influenza A Strains Influenced by a Mutation in Hemagglutinin Subunit 2

Pandemic 2009 H1N1 influenza A virus (2009 H1N1) differs from H1N1 strains that circulated in the past 50 years, but resembles the A/New Jersey/1976 H1N1 strain used in the 1976 swine influenza vaccine. We investigated whether sera from persons immunized with the 1976 swine influenza or recent seasonal influenza vaccines, or both, neutralize 2009 H1N1. Using retroviral pseudovirions bearing hemagglutinins on their surface (HA-pseudotypes), we found that 77% of the sera collected in 1976 after immunization with the A/New Jersey/1976 H1N1 swine influenza vaccine neutralized 2009 H1N1. Forty five percent also neutralized A/New Caledonia/20/1999 H1N1, a strain used in seasonal influenza vaccines during the 2000/01–2006/07 seasons. Among adults aged 48–64 who received the swine influenza vaccine in 1976 and recent seasonal influenza vaccines during the 2004/05–2008/09 seasons, 83% had sera that neutralized 2009 H1N1. However, 68% of age-matched subjects who received the same seasonal influenza vaccines, but did not receive the 1976 swine influenza vaccine, also had sera that neutralized 2009 H1N1. Sera from both 1976 and contemporary cohorts frequently had cross-neutralizing antibodies to 2009 H1N1 and A/New Caledonia/20/1999 that mapped to hemagglutinin subunit 2 (HA2). A conservative mutation in HA2 corresponding to a residue in the A/Solomon Islands/3/2006 and A/Brisbane/59/2007 H1N1 strains that circulated in the 2006/07 and 2007/08 influenza seasons, respectively, abrogated this neutralization. These findings highlight a cross-neutralization determinant influenced by a point mutation in HA2 and suggest that HA2 may be evolving under direct or indirect immune pressure.

CpG Oligonucleotides Improve the Protective Immune Response Induced by the Licensed Anthrax Vaccine

Abstract:  Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs act as immune adjuvants, improving the response elicited by a coadministered vaccine. Combining CpG ODN with anthrax vaccine adsorbed (AVA, the licensed human vaccine) increases the speed, magnitude, and avidity of the resultant antibody response. IgG Abs against anthrax protective antigen (PA) protect mice, guinuea pigs, and rhesus macaques from infection.

Immunogenicity and cross-reactivity of 2009-2010 inactivated seasonal influenza vaccine in US adults and elderly.

The campaign of 2009–2010 Northern Hemisphere seasonal vaccination was concurrent with the 2009 H1N1 pandemic. Using a hemagglutination inhibition (HAI) assay, we evaluated the immunogenicity and cross-reactivity of 2009–2010 inactivated trivalent influenza vaccine (TIV) in US adult and elderly populations. Vaccination of TIV resulted in a robust boost on the antibody response of all subjects to seasonal A/Brisbane/59/2007 (H1N1) and A/Uruguay/716/2007 (H3N2) with over 70% of recipients reaching a seroprotective titer of 40. B/Brisbane/60/2008 was the least immunogenic among the three seasonal vaccine strains with <30% of TIV recipients reaching a seroprotective titer of 40. TIV vaccination also induced a moderate boost on the pandemic specific antibody responses. Twenty-four percent of adults and 36% of elderly reached a seroprotective HAI titer of 40 or more against pandemic A/South Carolina/18/2009 (H1N1) after receiving TIV compared to 4% and 7% at the beginning of vaccination, respectively. In addition, 22% of adults and 34% of elderly showed an increase of 4-fold or more in A/South Carolina/18/2009 specific HAI titers after TIV vaccination. The pandemic specific cross-reactive antibodies strongly correlated with the post-vaccination HAI titers against the seasonal H3N2 vaccine strain in all subjects.

A Live Attenuated H1N1 M1 Mutant Provides Broad Cross-Protection against Influenza A Viruses, Including Highly Pathogenic A/Vietnam/1203/2004, in Mice

The emergence of novel influenza A H1N1 and highly pathogenic avian influenza (HPAI) H5N1 viruses underscores the urgency of developing efficient vaccines against an imminent pandemic. M(NLS-88R) (H1N1), an A/WSN/33 mutant with modifications in the multibasic motif 101RKLKR105 of the matrix (M1) protein and its adjacent region, was generated by reverse genetics. The M(NLS-88R) mutant had in vitro growth characteristics similar to those of wild-type A/WSN/33 (wt-WSN), but it was attenuated in mice. Vaccination with M(NLS-88R) not only fully protected mice from lethal homologous challenges but also prevented mortality caused by antigenically distinct H3N2 and H5N1 viruses. M(NLS-88R)-induced homologous protection was mainly antibody dependent, but cellular immunity was also beneficial in protecting against sublethal wt-WSN infection. Adoptive transfer studies indicated that both humoral and cellular immune responses were crucial for M(NLS-88R)-induced heterologous protection. Our study suggests an alternative approach to attenuate wt influenza viruses for the development of a pandemic vaccine with broad cross-protection.

Crystal Structures of Influenza A Virus Matrix Protein M1: Variations on a Theme

Matrix protein 1 (M1) of the influenza A virus plays multiple roles in virion assembly and infection. Interest in the pH dependence of M1s multiple functions led us to study the effect of subtle pH changes on M1 structure, resulting in the elucidation of a unique low-pH crystal structure of the N1-165-domain of A/WSN/33 (H1N1) M1 that has never been reported. Although the 2.2 Å crystal structure of M1 N-terminus shows a dimer with the two monomers interacting in a face-to-face fashion at low pH as observed earlier, a 44° rotation of the second monomer has led to a significantly different dimer interface that possibly affects dimer stability. More importantly, while one of the monomers is fully defined, the N-terminal half of the second monomer shows considerable disorder that appears inherent in the protein and is potentially physiologically relevant. Such disorder has not been observed in any other previously reported structure at either low or high pH conditions, despite similar crystallization pH conditions. By comparing our novel N1-165-domain structure with other low-pH or neutral-pH M1 structures, it appears that M1 can energetically access different monomer and dimer conformations, as well as oligomeric states, with varying degree of similarities. The study reported here provides further insights into M1 oligomerization that may be essential for viral propagation and infectivity.

Mutations to A/Puerto Rico/8/34 PB1 gene improves seasonal reassortant influenza A virus growth kinetics

It is desirable for influenza vaccine virus strains to have phenotypes that include good growth and hemagglutinin (HA) protein yield. The quality of these characteristics varies among the vaccine viruses and is usually due to multigenic effects. Many influenza A virus vaccine viruses are made as reassortants of the high yield virus A/Puerto Rico/8/34 (PR/8) and a circulating seasonal virus. Co-infection of eggs with the two viruses, and selection of reassortants with the HA and neuraminidase (NA) segments from the seasonal virus, can result in viruses that contain a mixture of internal genes derived from both the high yield virus and the circulating virus. Segment 2 (PB1), which encodes the RNA-dependent RNA polymerase, frequently cosegregates with the seasonal HA and NA segments. We asked whether mutations based on the seasonal PB1 genes could improve vaccine virus strains. Here we report that mutations to the PR/8 PB1 gene, based on differences observed between seasonal and PR/8 PB1 genes, accelerate egg and cell culture based replication for a reassortant virus containing HA and NA segments from the low yield A/Wyoming/03/2003 (H3N2) vaccine virus.

Iron overload by Superparamagnetic Iron Oxide Nanoparticles is a High Risk Factor in Cirrhosis by a Systems Toxicology Assessment

Superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent have been widely used in magnetic resonance imaging for tumor diagnosis and theranostics. However, there has been safety concern of SPIONs with cirrhosis related to excess iron-induced oxidative stress. In this study, the impact of iron overload by SPIONs was assessed on a mouse cirrhosis model. A single dose of SPION injection at 0.5 or 5 mg Fe/kg in the cirrhosis group induced a septic shock response at 24 h with elevated serum levels of liver and kidney function markers and extended impacts over 14 days including high levels of serum cholesterols and persistent low serum iron level. In contrast, full restoration of liver functions was found in the normal group with the same dosages over time. Analysis with PCR array of the toxicity pathways revealed the high dose of SPIONs induced significant expression changes of a distinct subset of genes in the cirrhosis liver. All these results suggested that excess iron of the high dose of SPIONs might be a risk factor for cirrhosis because of the marked impacts of elevated lipid metabolism, disruption of iron homeostasis and possibly, aggravated loss of liver functions.

Influenza A virus hemagglutinin glycosylation compensates for antibody escape fitness costs

Rapid antigenic evolution enables the persistence of seasonal influenza A and B viruses in human populations despite widespread herd immunity. Understanding viral mechanisms that enable antigenic evolution is critical for designing durable vaccines and therapeutics. Here, we utilize the primerID method of error-correcting viral population sequencing to reveal an unexpected role for hemagglutinin (HA) glycosylation in compensating for fitness defects resulting from escape from anti-HA neutralizing antibodies. Antibody-free propagation following antigenic escape rapidly selected viruses with mutations that modulated receptor binding avidity through the addition of N-linked glycans to the HA globular domain. These findings expand our understanding of the viral mechanisms that maintain fitness during antigenic evolution to include glycan addition, and highlight the immense power of high-definition virus population sequencing to reveal novel viral adaptive mechanisms.