Newcastle Disease Virus-Vectored Vaccines Expressing the Hemagglutinin or Neuraminidase Protein of H5N1 Highly Pathogenic Avian Influenza Virus Protect against Virus Challenge in Monkeys

H5N1 highly pathogenic avian influenza virus (HPAIV) causes periodic outbreaks in humans, resulting in severe infections with a high (60%) incidence of mortality. The circulating strains have low human-to-human transmissibility; however, widespread concerns exist that enhanced transmission due to mutations could lead to a global pandemic. We previously engineered Newcastle disease virus (NDV), an avian paramyxovirus, as a vector to express the HPAIV hemagglutinin (HA) protein, and we showed that this vaccine (NDV/HA) induced a high level of HPAIV-specific mucosal and serum antibodies in primates when administered through the respiratory tract. Here we developed additional NDV-vectored vaccines expressing either HPAIV HA in which the polybasic cleavage site was replaced with that from a low-pathogenicity strain of influenza virus [HA(RV)], in order to address concerns of enhanced vector replication or genetic exchange, or HPAIV neuraminidase (NA). The three vaccine viruses [NDV/HA, NDV/HA(RV), and NDV/NA] were administered separately to groups of African green monkeys by the intranasal/intratracheal route. An additional group of animals received NDV/HA by aerosol administration. Each of the vaccine constructs was highly restricted for replication, with only low levels of virus shedding detected in respiratory secretions. All groups developed high levels of neutralizing antibodies against homologous and heterologous strains of HPAIV and were protected against challenge with 2 × 10⁷ PFU of homologous HPAIV. Thus, needle-free, highly attenuated NDV-vectored vaccines expressing either HPAIV HA, HA(RV), or NA have been developed and demonstrated to be individually immunogenic and protective in a primate model of HPAIV infection. The finding that HA(RV) was protective indicates that it would be preferred for inclusion in a vaccine. The study also identified NA as an independent protective HPAIV antigen in primates. Furthermore, we demonstrated the feasibility of aerosol delivery of NDV-vectored vaccines.H5N1 highly pathogenic avian influenza virus (HPAIV) was first detected in human infections in 1997; previously, it had been found only in birds (11, 50). To date, this virus has been identified in 436 confirmed cases of human infection in 15 countries, 262 (60%) of which were fatal (75). The currently circulating H5N1 strains are characterized by low human-to-human transmissibility. This has been attributed, in part, to a preference for binding to α-2,3-linked sialic acids that are present in high concentrations throughout the avian respiratory tract but were thought to be found primarily in the lower human respiratory tract (57), although this explanation has been questioned (48, 49). It has also been observed that mutations in the PB2 subunit of the viral polymerase are necessary to confer the ability for the virus to be spread by aerosolized nasal droplets in ferrets (72). Whatever factors may be involved, there is widespread concern that the avian virus could mutate to enhance its transmissibility among humans, possibly resulting in a global pandemic (28, 50). For the avian H9N2 virus, which also has pandemic potential, it has been demonstrated that only five amino acid changes were sufficient for the virus to gain the ability to be spread by aerosolized nasal droplets in a ferret model (60). Thus, there is an urgent need for vaccines against HPAIV.Several vaccine strategies for HPAIV have been evaluated (reviewed in references 32 and 41), including inactivated and live attenuated vaccines. These efforts have been hampered by several factors. HPAIV strains are highly virulent for embryonated chicken eggs, the most widely used substrate for vaccine manufacture, and their rapid death following inoculation renders eggs unsuitable for efficient virus propagation. In addition, the major protective antigen, hemagglutinin (HA), administered either as a purified protein or in inactivated HPAIV virions, appears to be poorly immunogenic (69, 70). An additional factor complicating the development of HPAIV vaccines based on inactivated virus is the high cost and biohazard associated with HPAIV propagation, which must be done under enhanced biosafety level 3 (BSL-3) containment, although this problem might be addressed by the use of live attenuated reassortant influenza virus vaccines that contain the HPAIV glycoproteins on the background of an avirulent human influenza virus strain (24, 37). In addition, such reassortant strains might serve directly as live attenuated vaccines. Unfortunately, the latter approach may be limited by subtle and unpredictable incompatibility between the avian-origin glycoproteins and human-origin vaccine backgrounds acceptable for human use, which can result in overattenuation in vivo (24). There are also lingering concerns about the significant potential, with a live HPAIV vaccine, for reassortment between gene segments of the vaccine virus and circulating influenza virus strains, which might result in novel strains with unpredictable biological properties (63).We and others have been evaluating Newcastle disease virus (NDV) as a general human vaccine vector for emerging pathogens, including H5N1 HPAIV (7, 18-20, 29). NDV is an avian paramyxovirus that is antigenically unrelated to common human pathogens; hence, its use in humans should not be affected by host immunity to common pathogens. The many naturally occurring strains of NDV can be categorized into three pathotypes based on virulence in chickens: velogenic strains, causing severe disease with high mortality; mesogenic strains, causing disease of intermediate severity with low mortality; and lentogenic strains, causing mild or inapparent infections (reviewed in reference 2). Lentogenic, and sometimes mesogenic, strains of NDV are in wide use as live attenuated vaccines against velogenic NDV in poultry (2). When mesogenic or lentogenic NDV was administered to the respiratory tracts of nonhuman primates as a model for the immunization of humans, the virus was highly attenuated for replication, was shed only at low titers, appeared to remain restricted to the respiratory tract, and was highly immunogenic for the expressed foreign antigen (7). We recently demonstrated that a mesogenic strain of NDV expressing the HA protein of H5N1 HPAIV (NDV/HA) elicited high titers of neutralizing antibodies in serum following combined intranasal (i.n.) and intratracheal (i.t.) delivery in a nonhuman primate model (20). Vaccination of mice with a similar NDV-vectored vaccine protected them from HPAIV challenge (29). However, results obtained with mice do not reliably predict the efficacy of an influenza virus vaccine for human use, due to the pathophysiological and phylogenetic differences between mice and humans (71). In particular, mice may produce a potent immune response to HPAIV vaccines (64) that may not be reproduced in clinical trials (38). These considerations are especially important for a vaccine based on a live viral vector platform, since its immunogenicity, and therefore its protective efficacy, is directly linked to replication, which can differ greatly in various experimental animals versus humans (reviewed in references 6 and 9). Therefore, the protective efficacy of NDV-based vaccines against HPAIV challenge in nonhuman primate models—the closest model to humans—has remained unknown.The protease recognition sequence of the HA protein is one of the major determinants of avian influenza virus pathogenicity (62). HPAIV strains have a “polybasic” cleavage site, containing multiple basic amino acids, that is readily cleaved by ubiquitous intracellular subtilisin-like proteases, facilitating the replication and spread of the virus. In contrast, the HA cleavage site of low-pathogenicity strains contains fewer basic amino acids and depends on secretory trypsin-like proteases found in the respiratory and enteric tracts, resulting in more-localized infections (30, 62). The presence of a polybasic cleavage site in the H5 HA of any live vaccine raises some concern about the possibility of genetic exchange with circulating strains of influenza virus. It should be noted that genetic exchange involving paramyxoviruses is a rare event (14) that has been documented only once (61). However, elimination of the polybasic HA cleavage site would mitigate the effects of even this rare possibility of genetic exchange. Another concern was based on our previous finding that the HPAIV H5 HA protein is incorporated into the NDV envelope as a trimer (20), consistent with its presence in a functional form. While we previously showed that this did not enhance the pathogenicity of the NDV/HA recombinant in chickens (20), we could not rule out the possibility that it might confer an altered tropism on the NDV/HA virus in other systems. For example, a recombinant parainfluenza virus type 3 expressing the Ebola virus glycoprotein incorporated the foreign protein into its envelope, allowing cellular attachment and fusion of the vaccine virus independently of the vector''s own envelope glycoproteins (10).In addition to the HA protein, the neuraminidase (NA) protein is also present on the surfaces of influenza virus-infected cells and virions. Antibodies specific for NA are not thought to interfere with the initial viral attachment and penetration of host cells (36, 40, 54). However, NA-specific antibodies prevent the release of virus from infected cells, thereby decreasing viral spread (35), and they increase resistance to viral infection in humans (40, 47, 54). They also provide at least some protection against viruses bearing homologous or heterologous NA proteins of the same subtype in a mouse model (12, 56). NA also appears to evolve at a lower rate than HA, suggesting that NA-specific antibodies may provide broader protection than a vaccine utilizing HA alone (39). Therefore, it was important to assess the immunogenicity and protective efficacy of the HPAIV NA independently of those of HA, which has not previously been done in a human or nonhuman primate model.     

VCD spectroscopic properties of the β‐hairpin forming miniprotein CLN025 in various solvents

Electronic and vibrational circular dichroism are often used to determine the secondary structure of proteins, because each secondary structure has a unique spectrum. Little is known about the vibrational circular dichroic spectroscopic features of the β‐hairpin. In this study, the VCD spectral features of a decapeptide, YYDPETGTWY (CLN025), which forms a stable β‐hairpin that is stabilized by intramolecular weakly polar interactions and hydrogen bonds were determined. Molecular dynamics simulations and ECD spectropolarimetry were used to confirm that CLN025 adopts a β‐hairpin in water, TFE, MeOH, and DMSO and to examine differences in the secondary structure, hydrogen bonds, and weakly polar interactions. CLN025 was synthesized by microwave‐assisted solid phase peptide synthesis with N^α‐Fmoc protected amino acids. The VCD spectra displayed a (?,+,?) pattern with bands at 1640 to 1656 cm^?1, 1667 to 1687 cm^?1, and 1679 to 1686 cm^?1 formed by the overlap of a lower frequency negative couplet and a higher frequency positive couplet. A maximum IR absorbance was observed at 1647 to 1663 cm^?1 with component bands at 1630 cm^?1, 1646 cm^?1, 1658 cm^?1, and 1675 to 1680 cm^?1 that are indicative of the β‐sheet, random meander, either random meander or loop and turn, respectively. These results are similar to the results of others, who examined the VCD spectra of β‐hairpins formed by ^DPro‐Xxx turns and indicated that observed pattern is typical of β‐hairpins. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 442–450, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Microbiological quality of blue mussels (Mytilus edulis) in Nunavik, Quebec: a pilot study

This pilot study was aimed at documenting the presence of fecal indicators and enteric pathogens in blue mussels (Mytilus edulis) from 6 communities in Nunavik, Quebec. One to four 2?kg samples of mussels were collected at low tide in each community. Samples were investigated by enumeration methods for the fecal indicators enterococci, Escherichia coli, F-specific coliphages, Clostridium perfringens, and by molecular identification for the pathogens norovirus, Salmonella spp., Campylobacter jejuni, Campylobacter coli, and Campylobacter lari, verocytotoxin-producing E.?coli (particularly serovar O157:H7), Shigella spp., and Yersinia enterocolitica. In 5 communities, the presence of Giardia duodenalis and Cryptosporidium spp. was also tested by microscopy and molecular methods and that of Toxoplasma gondii was tested by molecular methods. Apart from small quantities of Clostridium perfringens in 2 samples, no bacterial or viral pathogens were detected in the mussels. Toxoplasma gondii was also not detected. However, G.?duodenalis and Cryptosporidium spp. were present in 18% and 73% of the samples investigated for these pathogens, respectively. When considering the indicators and the viral and bacterial pathogens investigated, the mussels examined were of good microbiological quality, but considering the presence of potentially zoonotic protozoa, it should be recommended that consumers cook the molluscs well before eating them.     

ATAD2B is a phylogenetically conserved nuclear protein expressed during neuronal differentiation and tumorigenesis

ATAD2 is an E2F target gene that is highly expressed in gastrointestinal and breast carcinomas. Here we characterize a related gene product, ATAD2B. Both genes are evolutionarily conserved, with orthologues present in all eukaryotic genomes examined. Human ATAD2B shows a high degree of similarity to ATAD2. Both contain an AAA domain and a bromodomain with amino acid sequences sharing 97% and 74% identity, respectively. The expression of ATAD2B was studied in the chicken embryo using a polyclonal antibody raised against a recombinant fragment of human ATAD2B. Immunohistochemistry revealed transient nuclear expression in subpopulations of developing neurons. The transient nature of the expression was confirmed by immunoblotting homogenates of the developing telencephalon. Cell fractionation was used to confirm the nuclear localization of ATAD2B in the developing nervous system: anti-ATAD2B recognizes a smaller band (approximately 160 kDa) in the nuclear fraction and a larger band (approximately 300 kDa) in the membrane fraction, suggesting that posttranslational processing of ATAD2B may regulate its transport to the nucleus. The expression of ATAD2B was also studied in human tumors. Oncomine and immunohistochemistry reveal ATAD2B expression in glioblastoma and oligodendroglioma; ATAD2B immunostaining was also elevated in human breast carcinoma. In tumors ATAD2B appears to be cytoplasmic or membrane bound, and not nuclear. Our observations suggest that ATAD2B may play a role in neuronal differentiation and tumor progression.     

THE VARIABLE GENOMIC ARCHITECTURE OF ISOLATION BETWEEN HYBRIDIZING SPECIES OF HOUSE MICE

Studies of the genetics of hybrid zones can provide insight into the genomic architecture of species boundaries. By examining patterns of introgression of multiple loci across a hybrid zone, it may be possible to identify regions of the genome that have experienced selection. Here, we present a comparison of introgression in two replicate transects through the house mouse hybrid zone through central Europe, using data from 41 single nucleotide markers. Using both genomic and geographic clines, we found many differences in patterns of introgression between the two transects, as well as some similarities. We found that many loci may have experienced the effects of selection at linked sites, including selection against hybrid genotypes, as well as positive selection in the form of genotypes introgressed into a foreign genetic background. We also found many positive associations of conspecific alleles among unlinked markers, which could be caused by epistatic interactions. Different patterns of introgression in the two transects highlight the challenge of using hybrid zones to identify genes underlying isolation and raise the possibility that the genetic basis of isolation between these species may be dependent on the local population genetic make-up or the local ecological setting.     

Type II Collagen Expression Is Regulated by Tissue-specific miR-675 in Human Articular Chondrocytes

miRNAs have been shown to be essential for normal cartilage development in the mouse. However, the role of specific miRNAs in cartilage function is unknown. Using rarely available healthy human chondrocytes (obtained from 8 to 50 year old patients), we detected a most highly abundant primary miRNA H19, whose expression was heavily dependent on cartilage master regulator SOX9. Across a range of murine tissues, expression of both H19- and H19-derived miR-675 mirrored that of cartilage-specific SOX9. miR-675 was shown to up-regulate the essential cartilage matrix component COL2A1, and overexpression of miR-675 rescued COL2A1 levels in H19- or SOX9-depleted cells. We thus provide evidence that SOX9 positively regulates COL2A1 in human articular chondrocytes via a previously unreported miR-675-dependent mechanism. This represents a novel pathway regulating cartilage matrix production and identifies miR-675 as a promising new target for cartilage repair.     

Specificity of Staphyloferrin B Recognition by the SirA Receptor from Staphylococcus aureus

Many organisms use sophisticated systems to acquire growth-limiting iron. Iron limitation is especially apparent in bacterial pathogens of mammalian hosts where free iron concentrations are physiologically negligible. A common strategy is to secrete low molecular weight iron chelators, termed siderophores, and express high affinity receptors for the siderophore-iron complex. Staphylococcus aureus, a widespread pathogen, produces two siderophores, staphyloferrin A (SA) and staphyloferrin B (SB). We have determined the crystal structure of the staphyloferrin B receptor, SirA, at high resolution in both the apo and Fe(III)-SB (FeSB)-bound forms. SirA, a member of the class III binding protein family of metal receptors, has N- and C-terminal domains, each composed of mainly a β-stranded core and α-helical periphery. The domains are bridged by a single α-helix and together form the FeSB binding site. SB coordinates Fe(III) through five oxygen atoms and one nitrogen atom in distorted octahedral geometry. SirA undergoes conformational change upon siderophore binding, largely securing two loops from the C-terminal domain to enclose FeSB with a low nanomolar dissociation constant. The staphyloferrin A receptor, HtsA, homologous to SirA, also encloses its cognate siderophore (FeSA); however, the largest conformational rearrangements involve a different region of the C-terminal domain. FeSB is uniquely situated in the binding pocket of SirA with few of the contacting residues being conserved with those of HtsA interacting with FeSA. Although both SirA and HtsA bind siderophores from the same α-hydroxycarboxylate class, the unique structural features of each receptor provides an explanation for their distinct specificity.