A Single Immunization with MVA Expressing GnGc Glycoproteins Promotes Epitope-specific CD8+-T Cell Activation and Protects Immune-competent Mice against a Lethal RVFV Infection

Background

Rift Valley fever virus (RVFV) is a mosquito-borne pathogen causing an important disease in ruminants often transmitted to humans after epizootic outbreaks in African and Arabian countries. To help combat the spread of the disease, prophylactic measures need to be developed and/or improved.

Methodology/Principal Findings

In this work, we evaluated the immunogenicity and protective efficacy of recombinant plasmid DNA and modified vaccinia virus Ankara (rMVA) vectored vaccines against Rift Valley fever in mice. These recombinant vaccines encoded either of two components of the Rift Valley fever virus: the viral glycoproteins (Gn/Gc) or the nucleoprotein (N). Following lethal challenge with live RVFV, mice immunized with a single dose of the rMVA-Gn/Gc vaccine showed no viraemia or clinical manifestation of disease, but mounted RVFV neutralizing antibodies and glycoprotein specific CD8+ T-cell responses. Neither DNA-Gn/Gc alone nor a heterologous prime-boost immunization schedule (DNA-Gn/Gc followed by rMVAGn/Gc) was better than the single rMVA-Gn/Gc immunization schedule with regards to protective efficacy. However, the rMVA-Gn/Gc vaccine failed to protect IFNAR^−/− mice upon lethal RVFV challenge suggesting a role for innate responses in protection against RVFV. Despite induction of high titer antibodies against the RVFV nucleoprotein, the rMVA-N vaccine, whether in homologous or heterologous prime-boost schedules with the corresponding recombinant DNA vaccine, only conferred partial protection to RVFV challenge.

Conclusions/Significance

Given the excellent safety profile of rMVA based vaccines in humans and animals, our data supports further development of rMVA-Gn/Gc as a vaccine strategy that can be used for the prevention of Rift Valley fever in both humans and livestock.     

Cutting edge: early IL-4 production governs the requirement for IL-27-WSX-1 signaling in the development of protective Th1 cytokine responses following Leishmania major infection

There are conflicting reports on the requirements for the IL-27-WSX-1 pathway in the development of Th type 1 responses and resistance to intracellular pathogens; although early IFN-gamma production and resistance to Leishmania major are impaired in the absence of WSX-1 signaling, WSX-1(-/-) mice generate robust IFN-gamma responses and control infection with other intracellular protozoan pathogens. In this report, we resolve these conflicting observations and demonstrate that, in the absence of IL-4, WSX-1 is not required for early IFN-gamma production and control of L. major. Thus, the requirement for WSX-1 signaling in Th type 1 cell differentiation is restricted to conditions in which IL-4 is produced.     

Involvement of Ssp-4-related carbohydrate epitopes in mammalian cell invasion by Trypanosoma cruzi amastigotes

We examined whether the expression of Ssp-4-related carbohydrate epitopes defined by monoclonal antibodies 1D9 and 2B7 was related to cell invasion by Trypanosoma cruzi amastigotes from different isolates and whether the highest expression of the epitope defined by MAb 1D9 would confer greater infectivity. Confocal microscopy showed that both epitopes localize to the membrane of amastigotes from 569, 588, 573, 587 and SC2005 isolates, similar to the G isolate, whereas the CL isolate showed a punctate and diffuse staining. Flow cytometry revealed inter- and intra-isolate variable expression of these epitopes. Apart from the lower expression of MAb 2B7 epitope by intracellular amastigotes of the SC2005 isolate, amastigotes from chagasic patient isolates expressed both epitopes similar to the G isolate, in contrast to CL isolate, that showed lower expression of both epitopes. MAb 1D9 did not react with CL isolate on immunoblots and reacted poorly with 588 and 587 parasites. MAb 2B7 preferentially reacted with an epitope on an 84 kDa component in G and 573 isolates. Invasion assays revealed that despite the fact that amastigotes from chagasic patient isolates displayed high levels of the epitope defined by MAb 1D9, only isolate 588 invaded host cells in levels comparable to that of isolate G. Both MAbs specifically inhibited cell invasion by G and 588, but not CL. These results suggested that the highest expression of MAb 1D9 epitope was not sufficient to confer higher infectivity on the isolate, and besides the two epitopes, other factors may modulate the invasiveness of extracellular amastigotes from the different isolates.     

The use of an integrative approach to improve accuracy of species identification and detection of new species in studies of stream fish diversity

Genetica - In this study, we made an inventory of the stream and headwater ichthyofauna of the left bank of the Itaipu Dam Reservoir, located in the lower part of the Upper Paraná River basin,...     

Hepatitis B Virus with X Gene Mutation Is Associated with the Majority of Serologically “Silent” Non-B,Non-C Chronic Hepatitis

Hepatitis B virus (HBV) with X gene mutations has been a putative pathogen of chronic hepatitis without serological markers of known hepatitis viruses. The aim of this study was to reconfirm whether the HBV with the X gene mutation is associated with these serologically “silent” non-B, non-C (NBNC) chronic hepatitis, alcoholic liver disease (ALD) and autoimmune hepatitis (AIH). HBV DNA was amplified from serum and sequenced in 30 patients with NBNC chronic hepatitis in comparison with 20 patients with ALD and 5 patients with AIH. HBV DNA was identified in 21 patients (70%) in NBNC chronic hepatitis by nested polymerase chain reaction while only one patient (5%) in ALD and none in AIH showed HBV DNA. Eighteen (85.7%) of the 21 identified HBV DNAs had an identical 8-nucleotide deletion mutation at the distal part of the X region. This mutation affected the core promoter and the enhancer II sequence of HBV DNA and created a translational stop codon which truncated the X protein by 20 amino acids from the C-terminal end. All the HBV DNAs had a precore mutation at the 83rd nucleotide resulting in disruption of HBe antigen synthesis. These results indicate that HBV mutants are closely associated with the majority of serologically “silent” NBNC chronic hepatitis cases and the population of such mutant HBV DNAs is not uniform.     

Two Functional Variants of IRF5 Influence the Development of Macular Edema in Patients with Non-Anterior Uveitis

Objective

Interferon (IFN) signaling plays a crucial role in autoimmunity. Genetic variation in interferon regulatory factor 5 (IRF5), a major regulator of the type I interferon induction, has been associated with risk of developing several autoimmune diseases. In the current study we aimed to evaluate whether three sets of correlated IRF5 genetic variants, independently associated with SLE and with different functional roles, are involved in uveitis susceptibility and its clinical subphenotypes.

Methods

Three IRF5 polymorphisms, rs2004640, rs2070197 and rs10954213, representative of each group, were genotyped using TaqMan® allelic discrimination assays in a total of 263 non-anterior uveitis patients and 724 healthy controls of Spanish origin.

Results

A clear association between two of the three analyzed genetic variants, rs2004640 and rs10954213, and the absence of macular edema was observed in the case/control analysis (P _FDR=5.07E-03, OR=1.48, CI 95%=1.14-1.92 and P _FDR=3.37E-03, OR=1.54, CI 95%=1.19-2.01, respectively). Consistently, the subphenotype analysis accordingly with the presence/absence of this clinical condition also reached statistical significance (rs2004640: P=0.037, OR=0.69, CI 95%=0.48-0.98; rs10954213: P=0.030, OR=0.67, CI 95%=0.47-0.96), thus suggesting that both IRF5 genetic variants are specifically associated with the lack of macular edema in uveitis patients.

Conclusion

Our results clearly showed for the first time that two functional genetic variants of IRF5 may play a role in the development of macular edema in non-anterior uveitis patients. Identifying genetic markers for macular edema could lead to the possibility of developing novel treatments or preventive therapies.     

Residual Tumor Cells That Drive Disease Relapse after Chemotherapy Do Not Have Enhanced Tumor Initiating Capacity

Although chemotherapy is used to treat most advanced solid tumors, recurrent disease is still the major cause of cancer-related mortality. Cancer stem cells (CSCs) have been the focus of intense research in recent years because they provide a possible explanation for disease relapse. However, the precise role of CSCs in recurrent disease remains poorly understood and surprisingly little attention has been focused on studying the cells responsible for re-initiating tumor growth within the original host after chemotherapy treatment. We utilized both xenograft and genetically engineered mouse models of non-small cell lung cancer (NSCLC) to characterize the residual tumor cells that survive chemotherapy treatment and go on to cause tumor regrowth, which we refer to as tumor re-initiating cells (TRICs). We set out to determine whether TRICs display characteristics of CSCs, and whether assays used to define CSCs also provide an accurate readout of a cell’s ability to cause tumor recurrence. We did not find consistent enrichment of CSC marker positive cells or enhanced tumor initiating potential in TRICs. However, TRICs from all models do appear to be in EMT, a state that has been linked to chemoresistance in numerous types of cancer. Thus, the standard CSC assays may not accurately reflect a cell’s ability to drive disease recurrence.     

Ecology and mating competition influence sexual dimorphism in Tanganyikan cichlids

Sexual selection contributes strongly to the evolution of sexual dimorphism among animal taxa. However, recent comparative analyses have shown that evolution of sexual dimorphism can be influenced by extrinsic factors like mating system and environment, and also that different types of sexual dimorphism may present distinct evolutionary pathways. Investigating the co-variation among different types of sexual dimorphism and their association with environmental factors can therefore provide important information about the mechanisms generating variation in sexual dimorphism among contemporary species. Using phylogenetic comparative analyses comparing 49 species of Tanganyikan cichlid fishes, we first investigated the pairwise relationship between three types of sexual dimorphism [size dimorphism (SSD), colour dimorphism (COD) and shape dimorphism (SHD)] and how they were related to the strength of pre- and post-copulatory sexual selection. We then investigated the influence of ecological features on sexual dimorphism. Our results showed that although SSD was associated with the overall strength of sexual selection it was not related to other types of sexual dimorphism. Also, SSD co-varied with female size and spawning habitat, suggesting a role for female adaptations to spawn in small crevices and shells influencing SSD in this group. Further, COD and SHD were positively associated and both show positive relationships with the strength of sexual selection. Finally, the level of COD and SHD was related to habitat complexity. Our results thus highlight distinct evolutionary pathways for different types of sexual dimorphism and further that ecological factors have influenced the evolution of sexual dimorphism in Tanganyikan cichlid fishes.     

Digestive flexibility during fasting in the characid fishHyphessobrycon luetkenii

Digestive flexibility is a widespread phenomenon among animals, and the congruence between empirical data and optimal digestion models strongly supports the idea that it has evolved by natural selection. However, current understanding of the evolution of this amazing flexibility is far from being comprehensive. Evidence from vertebrate tetrapods suggests that there are two major mechanisms for intestinal down‐regulation during fasting periods: a decrease in the number of enterocytes in the mucosal epithelium in endothermic species, and a transitional epithelium in concert with a marked hypotrophy of enterocytes in ectothermic species. Here, we analyze the intestinal changes, at the morphological and histological levels, occurring after 9 and 16 days of fasting in a small characid fish species (Hyphessobrycon luetkenii). We found that short‐term fasting was correlated with a marked down‐regulation of gut size (i.e., caeca and intestine dry mass fall to a 42.3%, while intestinal length was reduced to a 73.9% of the feeding values) and that these changes were accompanied by a shift in intestinal epithelial organization from a simple columnar to pseudostratified one. This result, in conjunction with data on changes in enterocyte turnover rates during fasting in other fish species, suggests that gut regulation at both levels, cell renewal rate and epithelia configuration, is the basal condition to all tetrapods. More data, especially in some key taxonomic groups (e.g., fish that follow an endothermic strategy), will be needed in order to reach a clear understanding of digestive flexibility evolution. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.