MAVS Is essential for primary CD4 + T cell immunity but not for recall T cell responses following an attenuated West Nile virus infection

ABSTRACT The use of pathogen recognition receptor (PRR) agonists and the molecular mechanisms involved have been the major focus of research in individual vaccine development. West Nile virus (WNV) nonstructural (NS) 4B-P38G mutant has several features for an ideal vaccine candidate, including significantly reduced neuroinvasiveness, induction of strong adaptive immunity, and protection of mice from wild-type (WT) WNV infection. Here, we determined the role of mitochondrial antiviral signaling protein (MAVS), the adaptor protein for RIG-I-like receptor in regulating host immunity against the NS4B-P38G vaccine. We found that Mavs −/− mice were more susceptible to NS4B-P38G priming than WT mice. Mavs −/− mice had a transiently reduced production of antiviral cytokines and an impaired CD4 + T cell response in peripheral organs. However, antibody and CD8 + T cell responses were minimally affected. NS4B-P38G induced lower type I interferon (IFN), IFN-stimulating gene, and proinflammatory cytokine responses in Mavs −/− dendritic cells and subsequently compromised the antigen-presenting capacity for CD4 + T cells. Interestingly, Mavs −/− mice surviving NS4B-P38G priming were all protected from a lethal WT WNV challenge. NS4B-P38G-primed Mavs −/− mice exhibited equivalent levels of protective CD4 + T cell recall response, a modestly reduced WNV-specific IgM production, but more robust CD8 + T cell recall response. Taken together, our results suggest that MAVS is essential for boosting optimal primary CD4 + T cell responses upon NS4B-P38G vaccination and yet is dispensable for host protection and recall T cell responses during secondary WT WNV infection. IMPORTANCE The production of innate cytokines induced by the recognition of pathogen recognition receptors (PRRs) via their cognate ligands are critical for enhancing antigen-presenting cell functions and influencing T cell responses during microbial infection. The use of PRR agonists and the underlying molecular mechanisms have been the major focus in individual vaccine development. Here, we determined the role of mitochondrial antiviral-signaling protein (MAVS), the adaptor protein for RIG-I like receptor in regulating host immunity against the live attenuated West Nile virus (WNV) vaccine strain, the nonstructural (NS) 4B-P38G mutant. We found that MAVS is important for boosting optimal primary CD4 + T cell response during NS4B-P38G vaccination. However, MAVS is dispensable for memory T cell development and host protection during secondary wild-type WNV infection. Overall, these results may be utilized as a paradigm to aid in the rational development of other efficacious live attenuated flavivirus vaccines

Host immunity in the protective response to vaccination with heat-killed Burkholderia mallei

<p>Abstract</p> <p>Background</p> <p>We performed initial cell, cytokine and complement depletion studies to investigate the possible role of these effectors in response to vaccination with heat-killed <it>Burkholderia mallei </it>in a susceptible BALB/c mouse model of infection.</p> <p>Results</p> <p>While protection with heat-killed bacilli did not result in sterilizing immunity, limited protection was afforded against an otherwise lethal infection and provided insight into potential host protective mechanisms. Our results demonstrated that mice depleted of either B cells, TNF-α or IFN-γ exhibited decreased survival rates, indicating a role for these effectors in obtaining partial protection from a lethal challenge by the intraperitoneal route. Additionally, complement depletion had no effect on immunoglobulin production when compared to non-complement depleted controls infected intranasally.</p> <p>Conclusion</p> <p>The data provide a basis for future studies of protection via vaccination using either subunit or whole-organism vaccine preparations from lethal infection in the experimental BALB/c mouse model. The results of this study demonstrate participation of B220⁺cells and pro-inflammatory cytokines IFN-γ and TNF-α in protection following HK vaccination.</p

Experimental Everglades Virus Infection of Cotton Rats (Sigmodon hispidus)

We characterized Everglades virus infection of cotton rats from South Florida to validate their role as reservoir hosts in the enzootic transmission cycle

One Health epidemic preparedness: Biosafety quality improvement training in Nigeria

Background and Aim: One of the key components of the O ne Health approach to epidemic preparedness is raising awareness and increasing the knowledge of emerging infectious diseases, prevention, and risk reduction. However, related research can involve significant risks to biosafety and biosecurity. For this purpose, we organized a multidisciplinary biosafety hands-on workshop to inform and increase the knowledge of infectious diseases and risk mitigation. This study aimed to describe the process and outcome of a hands-on biosafety training program using a One Health a pproach across a multidisciplinary and multi-specialty group in Nigeria. Materials and Methods: A face-to-face hands-on training for 48 participants was organized by the West African Center for Emerging Infectious Diseases (WAC-EID) at the Jos University Teaching Hospital, serving as a lead institution for the Nigeria project site. Topics covered included (1) an overview of the WAC-EID research; (2) overview of infection prevention and control; (3) safety in animal handling and restraint, sample collection, and processing; (4) safety in field studies including rodent, bird and bat handling; (5) safety practices in the collection of mosquito and other arthropod vectors; (6) personal protective equipment training (disinfection, donning and doffing); and (7) safety in sample collection, labeling, and transportation. The program was executed using a mixed method of slide presentations, practical hands-on sessions, and video demonstrations. Pre- and post-course evaluation assessments and evaluation measures were used to assess training. Results: A total of 48 trainees participated in this training, with 12 (25%), 16 (33.3%), 14 (29.2%), 6 (12.5%) categorized as ornithology, entomology, mammalogy, and clinical interest groups, respectively. The pass rate for the pre-test was 29.4%, while for the post-test, it was 57.1%, or a 28% improvement. 88.6% of the trainees rated the training as relevant to them. Conclusion: Didactic and hands-on biosafety training is relevant in this era of zoonotic epidemics and pandemic preparedness. During this training program, there was a clear demonstration of knowledge transfer that can change the current practices of participants and improve the safety of infectious diseases research

Effects of a contoured articular prosthetic device on tibiofemoral peak contact pressure: a biomechanical study

Many middle-aged patients are affected by localized cartilage defects that are neither appropriate for primary, nor repeat biological repair methods, nor for conventional arthroplasty. This in vitro study aims to determine the peak contact pressure in the tibiofemoral joint with a partial femoral resurfacing device (HemiCAP®, Arthrosurface Inc., Franklin, MA, USA). Peak contact pressure was determined in eight fresh-frozen cadaveric specimens using a Tekscan sensor placed in the medial compartment above the menisci. A closed loop robotic knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) with body weight ground reaction force (GRF), 30° flexion with twice the body weight (2tBW) GRF and dynamic knee-bending cycles with body weight GRF. The ground reaction force was adjusted to the living body weight of the cadaver donor and maintained throughout all cycles. Each specimen was tested under four different conditions: Untreated, flush HemiCAP® implantation, 1-mm proud implantation and 20-mm defect. A paired sampled t test to compare means (significance, P ≤ 0.05) was used for statistical analysis. On average, no statistically significant differences were found in any testing condition comparing the normal knee with flush device implantation. With the 1-mm proud implant, statistically significant increase of peak contact pressures of 217% (5° stance), 99% (dynamic knee bending) and 90% (30° stance with 2tBW) compared to the untreated condition was seen. No significant increase of peak contact pressure was evaluated with the 20-mm defect. The data suggests that resurfacing with the HemiCAP® does not lead to increased peak contact pressure with flush implantation. However, elevated implantation results in increased peak contact pressure and might be biomechanically disadvantageous in an in vivo application

Intra-articular temperatures of the knee in sports – An in-vivo study of jogging and alpine skiing

<p>Abstract</p> <p>Background</p> <p>Up to date, no information exists about the intra-articular temperature changes of the knee related to activity and ambient temperature.</p> <p>Methods</p> <p>In 6 healthy males, a probe for intra-articular measurement was inserted into the notch of the right knee. Each subject was jogging on a treadmill in a closed room at 19°C room temperature and skiing in a ski resort at -3°C outside temperature for 60 minutes. In both conditions, temperatures were measured every fifteen minutes intra-articulary and at the skin surface of the knee. A possible influence on joint function and laxity was evaluated before and after activity. Statistical analysis of intra-articular and skin temperatures was done using nonparametric Wilcoxon's sign rank sum test and Mann-Whitney's-U-Test.</p> <p>Results</p> <p>Median intra-articular temperatures increased from 31.4°C before activity by 2.1°C, 4°C, 5.8°C and 6.1°C after 15, 30, 45 and 60 min of jogging (all p ≤ 0.05). Median intra-articular temperatures dropped from 32.2°C before activity by 0.5°C, 1.9°C, 3.6°C and 1.1°C after 15, 30, 45 and 60 min of skiing (all n.s.). After 60 minutes of skiing (jogging), the median intra-articular temperature was 19.6% (8.7%) higher than the skin surface temperature at the knee. Joint function and laxity appeared not to be different before and after activity within both groups.</p> <p>Conclusion</p> <p>This study demonstrates different changes of intra-articular and skin temperatures during sports in jogging and alpine skiing and suggests that changes are related to activity and ambient temperature.</p

Vaccine-elicited receptor-binding site antibodies neutralize two New World hemorrhagic fever arenaviruses

While five arenaviruses cause human hemorrhagic fevers in the Western Hemisphere, only Junin virus (JUNV) has a vaccine. The GP1 subunit of their envelope glycoprotein binds transferrin receptor 1 (TfR1) using a surface that substantially varies in sequence among the viruses. As such, receptor-mimicking antibodies described to date are type-specific and lack the usual breadth associated with this mode of neutralization. Here we isolate, from the blood of a recipient of the live attenuated JUNV vaccine, two antibodies that cross-neutralize Machupo virus with varying efficiency. Structures of GP1–Fab complexes explain the basis for efficient cross-neutralization, which involves avoiding receptor mimicry and targeting a conserved epitope within the receptor-binding site (RBS). The viral RBS, despite its extensive sequence diversity, is therefore a target for cross-reactive antibodies with activity against New World arenaviruses of public health concern

Vaccine-elicited receptor-binding site antibodies neutralize two New World hemorrhagic fever arenaviruses

While five arenaviruses cause human hemorrhagic fevers in the Western Hemisphere, only Junin virus (JUNV) has a vaccine. The GP1 subunit of their envelope glycoprotein binds transferrin receptor 1 (TfR1) using a surface that substantially varies in sequence among the viruses. As such, receptor-mimicking antibodies described to date are type-specific and lack the usual breadth associated with this mode of neutralization. Here we isolate, from the blood of a recipient of the live attenuated JUNV vaccine, two antibodies that cross-neutralize Machupo virus with varying efficiency. Structures of GP1–Fab complexes explain the basis for efficient cross-neutralization, which involves avoiding receptor mimicry and targeting a conserved epitope within the receptor-binding site (RBS). The viral RBS, despite its extensive sequence diversity, is therefore a target for cross-reactive antibodies with activity against New World arenaviruses of public health concern

Respiratory Insufficiency Correlated Strongly with Mortality of Rodents Infected with West Nile Virus

West Nile virus (WNV) disease can be fatal for high-risk patients. Since WNV or its antigens have been identified in multiple anatomical locations of the central nervous system of persons or rodent models, one cannot know where to investigate the actual mechanism of mortality without careful studies in animal models. In this study, depressed respiratory functions measured by plethysmography correlated strongly with mortality. This respiratory distress, as well as reduced oxygen saturation, occurred beginning as early as 4 days before mortality. Affected medullary respiratory control cells may have contributed to the animals' respiratory insufficiency, because WNV antigen staining was present in neurons located in the ventrolateral medulla. Starvation or dehydration would be irrelevant in people, but could cause death in rodents due to lethargy or loss of appetite. Animal experiments were performed to exclude this possibility. Plasma ketones were increased in moribund infected hamsters, but late-stage starvation markers were not apparent. Moreover, daily subcutaneous administration of 5% dextrose in physiological saline solution did not improve survival or other disease signs. Therefore, infected hamsters did not die from starvation or dehydration. No cerebral edema was apparent in WNV- or sham-infected hamsters as determined by comparing wet-to-total weight ratios of brains, or by evaluating blood-brain-barrier permeability using Evans blue dye penetration into brains. Limited vasculitis was present in the right atrium of the heart of infected hamsters, but abnormal electrocardiograms for several days leading up to mortality did not occur. Since respiratory insufficiency was strongly correlated with mortality more than any other pathological parameter, it is the likely cause of death in rodents. These animal data and a poor prognosis for persons with respiratory insufficiency support the hypothesis that neurological lesions affecting respiratory function may be the primary cause of human WNV-induced death

Non-neutralizing antibodies elicited by recombinant Lassa-Rabies vaccine are critical for protection against Lassa fever

Lassa fever (LF), caused by Lassa virus (LASV), is a viral hemorrhagic fever for which no approved vaccine or potent antiviral treatment is available. LF is a WHO priority disease and, together with rabies, a major health burden in West Africa. Here we present the development and characterization of an inactivated recombinant LASV and rabies vaccine candidate (LASSARAB) that expresses a codon-optimized LASV glycoprotein (coGPC) and is adjuvanted by a TLR-4 agonist (GLA-SE). LASSARAB elicits lasting humoral response against LASV and RABV in both mouse and guinea pig models, and it protects both guinea pigs and mice against LF. We also demonstrate a previously unexplored role for non-neutralizing LASV GPC-specific antibodies as a major mechanism of protection by LASSARAB against LF through antibody-dependent cellular functions. Overall, these findings demonstrate an effective inactivated LF vaccine and elucidate a novel humoral correlate of protection for LF.NIH grants R01 AI105204 to M.J.S., by the Jefferson Vaccine Center, and by the Fundação para a Ciência e Tecnologia (FCT) scholarship PD/BD/105847/2014 (to T.A.-M.). This work was also funded in part through the NIAID Division of Intramural Research and the NIAID Division of Clinical Research, Battelle Memorial Institute’s prime contract with the U.S. National Institute of Allergy and Infectious Diseases (NIAID) under Contract No. HHSN272200700016Iinfo:eu-repo/semantics/publishedVersio