Configuration of the action observation network depends on the goals of the observer

Observing the actions of others engages a core action observation network (AON) that includes the bilateral inferior frontal cortex (IFC), posterior superior temporal sulcus (pSTS) and inferior parietal lobule (IPL) (Caspers et al., 2010). Each region in the AON has functional properties that are heterogeneous and include representing the perceptual properties of action, predicting action outcomes and making inferences as to the goals of the actor. Critically, recent evidence shows that neural representations within the pSTS are sharpened when attending to the kinematics of the actor, such that the top-down guided attention reshapes underlying neural representations. In this study we evaluate how attention alters network connectivity within the AON as a system. Cues directed participant's attention to the goal, kinematics, or identity depicted in short action animations while brain responses were measured by fMRI. We identified those parcels within the AON with functional connectivity modulated by task. Results show that connectivity between the right pSTS and right IFC, and bilateral extended STS (STS+) were modulated during action observation such that connections were strengthened when the participant was attending to the action than goal. This finding is contrasted by the univariate results, which no univariate modulations in these brain regions except for right IFC. Using the functional networks defined by Yeo et al. (2011), we identified the parcels that are modulated by the attention to consist mainly of the fronto-parietal control network and default mode networks. These results are consistent with models of top-down feedback from executive system in the IFC to pSTS and implicates a right lateralized dual pathway model for action observation when focused on whole-body kinematics.

An Image Registration-Based Method for EPI Distortion Correction Based on Opposite Phase Encoding (COPE)

Surprisingly, estimated voxel displacement maps (VDMs), based on image registration, seem to work just as well to correct geometrical distortion in functional MRI data (EPI) as VDMs based on actual information about the magnetic field. In this article, we compare our new image registration-based distortion correction method ‘COPE’ to an implementation of the pixelshift method. Our approach builds on existing image registration-based techniques using opposite phase encoding, extending these by local cost aggregation. Comparison of these methods with 3T and 7T spin-echo (SE) and gradient-echo (GE) data show that the image registration-based method is a good alternative to the fieldmap-based EPI distortion correction method.

Attenuated dendritic cell function in BALB/c mice following HPAI vaccination results from failed C-type lectin receptor signaling (P4309)

Highly pathogenic avian influenza (HPAI) has an approximate 60% fatality rate in humans. In the United States, a vaccine for HPAI has been manufactured and stockpiled using FDA approved methods for seasonal vaccines. Compared to seasonal vaccines, the HPAI vaccine is less immunogenic in humans despite similar production methods. We developed a mouse model of influenza vaccination to examine differences in the host immune response to these vaccines. Mice that received the seasonal vaccine produced a robust neutralizing antibody response whereas no neutralizing antibodies were detected following HPAI vaccination. Dendritic cells (DCs) cultured with HPAI vaccine had decreased expression of activation markers CD40 and CD86, and produced significantly lower levels of cytokines IL-6, IL-12, and TNF-α compared to those treated with seasonal vaccine. C-type lectin receptors have been implicated as a class of pattern recognition receptors in innate immunity and immunization. Pretreatment with mannan diminished cytokine induction by DCs in a dose dependent manner following seasonal but not HPAI vaccine treatment, suggesting a role for C-type lectin receptors in DC activation by influenza vaccines. These findings implicate a potential mechanism for attenuated DC function following HPAI vaccination and may explain the lack of immunogenicity of the currently approved HPAI vaccine.

Alum adjuvant rescues HPAI vaccine immunogenicity and survival in BALB/c mice following H5N1 infection (113.30)

Highly pathogenic avian influenza (HPAI) is an emerging infectious virus with an approximate 60% fatality rate in humans. In the United States, a vaccine for H5N1 has been developed and stockpiled in case of a pandemic. This vaccine demonstrated low immunogenicity in human clinical trials with only 22% of recipients developing protective antibody titers. Previous studies using a lethal challenge ferret model have shown that supplementing the H5N1 vaccine with an alum adjuvant can improve immunogenicity and survival. We developed a lethal challenge mouse model of H5N1 vaccination to examine differences in innate immune responses to the vaccine alone or in the presence of an alum adjuvant. Mice treated with the adjuvanted vaccine showed significantly lower weight loss and higher survival than mice treated with the nonadjuvanted vaccine. Further, mice treated with adjuvanted vaccine had higher neutralizing antibody titers when compared to mice that received the nonadjuvanted vaccine. In vitro, dendritic cells (DCs) cultured with the adjuvanted vaccine had increased expression of the activation markers CD40 and CD86 compared to DCs treated with the nonadjuvanted vaccine. Interestingly, neither treatment induced activation of Toll-like receptors or the production of cytokines IL-6, IL-12, or TNF-α. Taken together, our results suggest that the alum adjuvant rescues immunogenicity and improves survival in the host.

Delta inulin polysaccharide adjuvant enhances the ability of split-virion H5N1 vaccine to protect against lethal challenge in ferrets

BACKGROUND

The reduced immunogenicity of the H5 hemagglutinin (HA), compared to seasonal HA serotypes, has stimulated searches for effective adjuvants to improve H5 vaccine efficacy. This study examined the immunogenicity and protective efficacy in ferrets immunized with a split-virion H5N1 vaccine combined with Advax™, a novel delta inulin-based polysaccharide adjuvant technology that has previously demonstrated ability to augment humoral and cellular immunity to co-administered antigens.

METHODS

Ferrets were vaccinated twice 21 days apart with 7.5 μg or 22.5 μg of a split-virion preparation of A/Vietnam/1203/2004 with or without adjuvant. An additional group received just one immunization with 22.5 μg HA plus adjuvant. Serum antibodies were measured by hemagglutination inhibition and microneutralization assays. Vaccinated animals were challenged intranasally 21 days after the last immunization with 10(6) EID(50) of the homologous strain. Morbidity was assessed by observed behavior, weight loss, temperature, cytopenias, histopathology, and viral load.

RESULTS

No serum neutralization antibody was detected after two immunizations with unadjuvanted vaccine. Two immunizations with high or low dose adjuvanted vaccine stimulated high neutralizing antibody titers. Survival was 100% in all groups receiving adjuvanted-vaccine including the single dose group, compared to 67% survival with unadjuvanted vaccine, and 0% survival in saline or adjuvant-alone controls. Minimal morbidity was seen in all animals receiving adjuvanted vaccine, and was limited to rhinorrhea and mild thrombocytopenia, without fever, weight loss, or reduced activity. H5N1 virus was cleared from the nasal wash by day 4 post-challenge only in animals receiving adjuvanted vaccine which also prevented viral invasion of the brain in most animals.

CONCLUSIONS

In this initial study, Advax™ adjuvant formulations improved the protective efficacy of a split-virion H5N1 vaccine as measured by significantly enhanced immunogenicity, survival, and reduced morbidity.

A chimeric multi-human epidermal growth factor receptor-2 B cell epitope peptide vaccine mediates superior antitumor responses

Immunotherapeutic approaches to cancer should focus on novel undertakings that modulate immune responses by synergistic enhancement of antitumor immunological parameters. Cancer vaccines should preferably be composed of multiple defined tumor Ag-specific B and T cell epitopes. To develop a multiepitope vaccine, 12 high ranking B cell epitopes were identified from the extracellular domain of the human epidermal growth factor receptor-2 (HER-2) oncoprotein by computer-aided analysis. Four novel HER-2 B cell epitopes were synthesized as chimeras with a promiscuous T cell epitope (aa 288-302) from the measles virus fusion protein (MVF). Two chimeric peptide vaccines, MVF HER-2(316-339) and MVF HER-2(485-503) induced high levels of Abs in outbred rabbits, which inhibited tumor cell growth. In addition, Abs induced by a combination of two vaccines, MVF HER-2(316-339) and MVF HER-2(628-647) down-modulated receptor expression and activated IFN-gamma release better than the individual vaccines. Furthermore, this multiepitope vaccine in combination with IL-12 caused a significant reduction (p = 0.004) in the number of pulmonary metastases induced by challenge with syngeneic tumor cells overexpressing HER-2. Peptide Abs targeting specific sites in the extracellular domain may be used for exploring the oncoprotein's functions. The multiepitope vaccine may have potential application in the treatment of HER-2-associated cancers.