Correlated evolution of oxidative physiology and MHC-based immunosurveillance in birds.

Maintenance and activation of the immune system incur costs, not only in terms of substrates and energy but also via collateral oxidative damage to host cells or tissues during immune response. So far, associations between immune function and oxidative damage have been primarily investigated at intra-specific scales. Here, we hypothesized that pathogen-driven selection should favour the evolution of effective immunosurveillance mechanisms (e.g. major histocompatibility complex, MHC) and antioxidant defences to mitigate oxidative damage resulting from immune function. Using phylogenetically informed comparative approaches, we provided evidence for the correlated evolution of host oxidative physiology and MHC-based immunosurveillance in birds. Species selected for more robust MHC-based immunosurveillance (higher gene copy numbers and allele diversity) showed stronger antioxidant defences, although selection for MHC diversity still showed a positive evolutionary association with oxidative damage to lipids. Our results indicate that historical pathogen-driven selection for highly duplicated and diverse MHC could have promoted the evolution of efficient antioxidant mechanisms, but these evolutionary solutions may be insufficient to keep oxidative stress at bounds. Although the precise nature of mechanistic links between the MHC and oxidative stress remains unclear, our study suggests that a general evolutionary investment in immune function may require co-adaptations at the level of host oxidative metabolism.

Serological Positivity against Selected Flaviviruses and Alphaviruses in Free-Ranging Bats and Birds from Costa Rica Evidence Exposure to Arboviruses Seldom Reported Locally in Humans.

Arboviruses have two ecological transmission cycles: sylvatic and urban. For some, the sylvatic cycle has not been thoroughly described in America. To study the role of wildlife in a putative sylvatic cycle, we sampled free-ranging bats and birds in two arbovirus endemic locations and analyzed them using molecular, serological, and histological methods. No current infection was detected, and no significant arbovirus-associated histological changes were observed. Neutralizing antibodies were detected against selected arboviruses. In bats, positivity in 34.95% for DENV-1, 16.26% for DENV-2, 5.69% for DENV-3, 4.87% for DENV-4, 2.43% for WNV, 4.87% for SLEV, 0.81% for YFV, 7.31% for EEEV, and 0.81% for VEEV was found. Antibodies against ZIKV were not detected. In birds, PRNT results were positive against WNV in 0.80%, SLEV in 5.64%, EEEV in 8.4%, and VEEV in 5.63%. An additional retrospective PRNT analysis was performed using bat samples from three additional DENV endemic sites resulting in a 3.27% prevalence for WNV and 1.63% for SLEV. Interestingly, one sample resulted unequivocally WNV positive confirmed by serum titration. These results suggest that free-ranging bats and birds are exposed to not currently reported hyperendemic-human infecting Flavivirus and Alphavirus; however, their role as reservoirs or hosts is still undetermined.

Identification of Amino Acid Residues Required for Inhibition of Host Gene Expression by Influenza Virus A/Viet Nam/1203/2004 H5N1 PA-X.

PA-X is a nonstructural protein of influenza A virus (IAV), which is encoded by the polymerase acidic (PA) N-terminal region that contains a C-terminal +1 frameshifted sequence. IAV PA-X protein modulates virus-induced host innate immune responses and viral pathogenicity via suppression of host gene expression or cellular shutoff, through cellular mRNA cleavage. Highly pathogenic avian influenza viruses (HPAIV) of the H5N1 subtype naturally infect different avian species, they have an enormous economic impact in the poultry farming, and they also have zoonotic and pandemic potential, representing a risk to human public health. In the present study, we describe a novel bacterium-based approach to identify amino acid residues in the PA-X protein of the HPAIV A/Viet Nam/1203/2004 H5N1 that are important for its ability to inhibit host protein expression or cellular shutoff activity. Identified PA-X mutants displayed a reduced shutoff activity compared to that of the wild-type A/Viet Nam/1203/2004 H5N1 PA-X protein. Notably, this new bacterium-based screening allowed us to identify amino acid residues widely distributed over the entire N-terminal region of PA-X. Furthermore, we found that some of the residues affecting A/Viet Nam/1203/2004 H5N1 PA-X host shutoff activity also affect PA polymerase activity in a minigenome assay. This information could be used for the rational design of new and more effective compounds with antiviral activity against IAV. Moreover, our results demonstrate the feasibility of using this bacterium-based approach to identify amino acid residues important for the activity of viral proteins to inhibit host gene expression. IMPORTANCE Highly pathogenic avian influenza viruses continue to pose a huge threat to global animal and human health. Despite of the limited genome size of Influenza A virus (IAV), the virus encodes eight main viral structural proteins and multiple accessory nonstructural proteins, depending on the IAV type, subtype, or strain. One of the IAV accessory proteins, PA-X, is encoded by the polymerase acidic (PA) protein and is involved in pathogenicity through the modulation of IAV-induced host inflammatory and innate immune responses. However, the molecular mechanism(s) of IAV PA-X regulation of the host immune response is not well understood. Here, we used, for the first time, a bacterium-based approach for the identification of amino acids important for the ability of IAV PA-X to induce host shutoff activity and describe novel residues relevant for its ability to inhibit host gene expression, and their contribution in PA polymerase activity.

Foraging strategies and physiological status of a marine top predator differ during breeding stages.

Habitat characteristics determine the presence and distribution of trophic resources shaping seabirds' behavioural responses which may result in physiological consequences. Such physiological consequences in relation to foraging strategies of different life-history stages have been little studied in the wild. Thus, we aim to assess differences in oxidative status, condition (fat stores, i.e. triglyceride levels, TRI), stress (Heterophil/Lymphocyte (H/L) ratio), and leukocyte profiles between incubation and chick rearing highlighting the role of foraging strategies in a seabird (Calonectris diomedea). Chick rearing was more energetically demanding and stressful than incubation as demonstrated by high stress levels (H/L ratio and leukocytes) and lower body stores (assessed by TRI and the increment of weight) due to the high energy requirements of rearing chicks. Also, our results make reconsider the simplistic trade-off model where reproduction increases metabolism and consequently the rate of oxidative stress. In fact, high energy expenditure (VeDBA) during chick rearing was correlated with low levels of oxidative damage likely due to mechanisms at the level of mitochondrial inner membranes (uncoupling proteins or low levels of oxygen partial pressure). Further (more distant) and longer (more days) foraging trips were performed during incubation, when antioxidants showed low levels compared to chick rearing due to incubation fasting, a change in diet, or a combination of these factors; but unlikely because of oxidative shielding since no relation was found between oxidative damage and antioxidant capacity. Males showed higher numbers of monocytes which were positively correlated with antioxidant capacity compared to females, suggesting sexual differences in immune profiles. Species-specific costs and energetic demands of different breeding phases trigger behavioural and physiological adjustments.

Comprehensive transcriptome characterization of Grus japonensis using PacBio SMRT and Illumina sequencing.

The red-crowned crane (Grus japonensis) is an endangered species distributed across southeast Russia, northeast China, Korea, and Japan. Here, we sequenced for the first time the full-length unreferenced transcriptome of red-crowned crane mixed samples using a PacBio Sequel platform. A total of 359,136 circular consensus sequences (CCS) were obtained via clustering to remove redundancy. A total of 303,544 full-length non-chimeric sequences were identified by judging whether CCS contained 5' and 3' adapters, and the poly(A) tail. Eight samples were sequenced using Illumina, and PacBio sequencing data were corrected according to the collected Illumina data to obtain more accurate full-length transcripts. A total of 4,100 long non-coding RNAs, 13,115 simple sequences repeat loci and 29 transcription factor families were identified. The expression of lncRNAs and TFs in pancreas was lowest comparing with other tissues. Many enriched immune-related transmission pathways (MHC and IL receptors) were identified in the spleen. This study will contribute to a better understanding of the gene structure and post-transcriptional regulatory network, and provide references for future studies on red-crowned cranes.

Repeated MDA5 Gene Loss in Birds: An Evolutionary Perspective.

Two key cytosolic receptors belonging to the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) family sense the viral RNA-derived danger signals: RIG-I and melanoma differentiation-associated protein 5 (MDA5). Their activation establishes an antiviral state by downstream signaling that ultimately activates interferon-stimulated genes (ISGs). While in rare cases RIG-I gene loss has been detected in mammalian and avian species, most notably in the chicken, MDA5 pseudogenization has only been detected once in mammals. We have screened over a hundred publicly available avian genome sequences and describe an independent disruption of MDA5 in two unrelated avian lineages, the storks (Ciconiiformes) and the rallids (Gruiformes). The results of our RELAX analysis confirmed the absence of negative selection in the MDA5 pseudogene. In contrast to our prediction, we have shown, using multiple dN/dS-based approaches, that the MDA5 loss does not appear to have resulted in any compensatory evolution in the RIG-I gene, which may partially share its ligand-binding specificity. Together, our results indicate that the MDA5 pseudogenization may have important functional effects on immune responsiveness in these two avian clades.

Seasonal variation in sex-specific immunity in wild birds.

Whilst the immune system often varies seasonally and exhibits differences between males and females, the general patterns in seasonality and sex differences across taxa have remained controversial. Birds are excellent model organisms to assess these patterns, because the immune system of many species is well characterised. We conducted a meta-analysis using 41 wild bird species from 24 avian families to investigate sex differences and seasonal (breeding/non-breeding) variations in immune status, including white blood cell counts, phytohaemagglutinin (PHA) test, bacteria-killing ability (BKA), haemolysis and haemagglutination assays. We found male-biased macrophage concentration, BKA and haemolysis titers, but only during the breeding season. Sex-specific heterophil concentrations, heterophil/lymphocyte ratios and PHA responses differed between breeding and non-breeding, suggesting larger changes in males than in females. Importantly, sex differences in immune status are stronger during the breeding period than during the non-breeding period. Taken together, our study suggests that both seasonal variation and sex differences in immune system are common in birds, although their associations are more complex than previously thought.

The bird's immune response to avian pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) cause colibacillosis in birds, a syndrome of severe respiratory and systemic disease that constitutes a major threat due to early mortality, condemnation of carcasses and reduced productivity. APEC can infect different types of birds in all commercial settings, and birds of all ages, although disease tends to be more severe in younger birds likely a consequence of an immature immune system. APEC can act as both primary and secondary pathogens, with predisposing factors for secondary infections including poor housing conditions, respiratory viral and Mycoplasma spp. infections or vaccinations. Controlled studies with APEC as primary pathogens have been used to study the bird's immune response to APEC, although it may not always be representative of natural infections which may be more complex due to the presence of secondary agents, stress and environmental factors. Under controlled experimental conditions, a strong early innate immune response is induced which includes host defence peptides in mucus and a cellular response driven by heterophils and macrophages. Both antibody and T-cell mediated adaptive responses have been demonstrated after vaccination. In this review we will discuss the bird's immune response to APEC as primary pathogen with a bias towards the innate immune response, as mechanistic adaptive studies clearly form a much more limited body of work despite numerous vaccine trials.

Azithromycin potentiates avian IgY effect against Pseudomonas aeruginosa in a murine pulmonary infection model.

Cystic fibrosis (CF) patients are at risk of acquiring chronic Pseudomonas aeruginosa lung infections. The biofilm mode of growth of P. aeruginosa induces tolerance to antibiotics and the host response; accordingly, treatment failure occurs. Supplemental azithromycin has proven beneficial in CF owing to potential immunomodulatory mechanisms. Clinical studies have demonstrated a reduction in exacerbations in CF patients by avian IgY anti-Pseudomonas immunotherapy. We hypothesise that azithromycin pre-treatment could potentiate the observed anti-Pseudomonas effect of IgY opsonisation in vivo. Evaluation of phagocytic cell capacity was performed using in vitro exposure of azithromycin pre-treated human polymorphonuclear neutrophils to IgY opsonised P. aeruginosa PAO3. A murine lung infection model using nasal planktonic P. aeruginosa inoculation and successive evaluation 24 h post-infection was used to determine lung bacteriology and subsequent pulmonary inflammation. Combined azithromycin treatment and IgY opsonisation significantly increased bacterial killing compared with the two single-treated groups and controls. In vivo, significantly increased bacterial pulmonary elimination was revealed by combining azithromycin and IgY. A reduction in the inflammatory markers mobiliser granulocyte colony-stimulating factor (G-CSF), macrophage inflammatory protein 2 (MIP-2) and interleukin 1 beta (IL-1ß) paralleled this effect. Combination of azithromycin and anti-Pseudomonas IgY potentiated the killing and pulmonary elimination of P. aeruginosa in vitro and in vivo. The augmented effect of combinatory treatment with azithromycin and IgY constitutes a potential clinical application for improving anti-Pseudomonas strategies.

Cloning and structural analysis of complement component 3d in wild birds provides insight into its functional evolution.

Complement component 3 d (C3d) is the final cleavage product of the complement component C3 and serves as a crucial role in link innate and adaptive immunity, and increase B-cell sensitivity to an antigen by 1000-10000 fold. The crystal structure of human C3d revealed there are two distinct surfaces, a convex surface containing the thioester-constituting residues that mediate covalent binding to the target antigen, and a concave surface with an acidic pocket responsible for interaction with CR2. In this study, we cloned and sequenced cDNA fragment encoding C3d region from 15 wild bird species. Then, the C3d sequences from wild birds, chicken and mammals were aligned to construct phylogenetic trees. Phylogenetic tree displayed two main branches, indicating mammals and birds, but the bird C3d branch was divided into two main parts, with five wild birds (Ardeola bacchus, Zoothera, Bubo, Crossoptilon mantchuricum and Caprimulgus europaeus) clustering much closer to mammals. In addition, the C3d proteins of Ardeola bacchus, Bubo, Crossoptilon mantchuricum and Caprimulgus europaeus contained a Glu163 residue at the position at which Lys163 was found in other birds. However, Glu163 have the same charge polarity as Asp163, which is the key amino acid residue comprising the acidic pocket combined with CR2 found at this position in mammals, and Zoothera also possessed Asp163 at this position. Structure modeling analyses also verified that the C3ds of these five wild bird species exhibited the amino acid sequence and structure comprising the typical acidic pocket found in mammals that is required for combination with B cell surface receptors, which contribute electrostatic forces to interact with CR2. Our investigations indicate that some bird C3ds may already have the ability to bind with CR2 by electrostatic force, like mammals. As Ardeola bacchus, Zoothera, Bubo, Crossoptilon mantchuricum and Caprimulgus europaeus have more typical C3d concave acid pockets and thus a stronger ability to bind CR2, we speculate that these five wild birds may have a solider immunity against pathogens. Our phylogenetic and structural analyses of bird C3ds provide insights on the evolutionary divergence in the function of immune factors of avian and mammalian.

Detection of anti-Toxoplasma gondiiantibodies in wild free-living birds and mammals from the northwest region of São Paulo state, Brazil / Detecção de anticorpos anti-Toxoplasma gondiiem aves e mamíferos silvestres de vida livre da região noroeste do estado de São Paulo, Brasil

Toxoplasmosis is a protozoonosis caused by an obligate intracellular parasite named Toxoplasma gondii, which can infect humans and a large number of homeothermic animal species with worldwide distribution. The present study aimed to detect anti-T. gondii antibodies from serological samples of free-living wild animals from the northwest region of São Paulo state, Brazil. Thirty-two samples (eight from birds and 24 from mammals) were analyzed by the modified agglutination test (MAT) using 5 cut-off points for birds and 25 for mammals. Seropositivity was observed in 25% (2/8) of birds, including the species Rupornis magnirostris (roadside hawk) and Caracara plancus (southern caracara), and 29.2% (7/24) animals were seropositive among mammals, including one hoary fox (Lycalopex vetulus), two maned wolves (Chrysocyon brachyurus), one black howler monkey (Alouatta caraya), two crab-eating foxes (Cerdocyon thous) and one gray brocket deer (Mazama gouazoubira). The results obtained with the present study indicate the exposure to T. gondiiof free-living wild animals from the northwest region of São Paulo state and, therefore, that they probably play a role in the transmission and maintenance of T. gondii in the environment they inhabit. Thus, identification of the infection in several animal species in the region indicates the environmental contamination of the area. Studies of this nature may help to understand the importance of the prevention and control of this disease in Brazil.(AU)

A toxoplasmose é uma protozoonose causada por um parasita intracelular obrigatório denominado Toxoplasma gondii, que pode infectar os humanos e um vasto número de espécies animais homeotérmicas, apresentando distribuição mundial. O presente estudo objetivou a detecção de anticorpos anti-T. gondii a partir de amostras sorológicas de animais silvestres de vida livre da região noroeste do estado de São Paulo. Foram analisadas 32 amostras (oito de aves e 24 de mamíferos) por meio do teste de aglutinação modificado (MAT), utilizando ponto de corte 5 para as aves e 25 para os mamíferos. Soropositividade foi observada em 25% (2/8) das aves, incluindo as espécies Rupornis magnirostris (gavião-carijó) e Caracara plancus (carcará); entre os mamíferos, 29,2% (7/24) foram soropositivos incluindo uma raposa-do-campo (Lycalopex vetulus), dois lobos-guará (Chrysocyon brachyurus), um bugio-preto (Alouatta caraya), dois cachorros-do-mato (Cerdocyon thous) e um veado-catingueiro (Mazama gouazoubira). Os resultados obtidos com o presente estudo indicam a exposição dos animais selvagens de vida livre a T. gondii na região noroeste do estado de São Paulo e, portanto, que provavelmente apresentam papel na transmissão e manutenção de T. gondii no meio ambiente em que vivem. Assim, a identificação da infecção em várias espécies de animais na região indica a contaminação ambiental da área. Estudos dessa natureza podem ajudar no entendimento sobre a prevenção e o controle dessa importante doença no Brasil.(AU)

Avian host defense cathelicidins: structure, expression, biological functions, and potential therapeutic applications.

Host defense peptides (HDP) are multifunctional effectors of the innate immune system, which has antimicrobial and pleiotropic immunomodulatory functions. Although there is a very sophisticated superposition of adaptive immune systems in vertebrates, this system is still essential. As an important family of HDP, cathelicidins are also known for their broad-spectrum antibacterial activity against bacteria, fungi, and enveloped viruses. It has been found in humans and other species, including cattle, pigs, sheep, goats, chickens, rabbits, and some kind of fish. Among them, cathelicidins in birds were described for the first time in 2005. This review focuses on the structure, biological activities, expression, and regulation of avian cathelicidin, especially main effects of host defense cathelicidin on potential therapeutic applications. According to the results obtained both in vitro and in vivo, good perspectives have been opened for cathelicidin. Nevertheless, further studies are needed to better characterize the mechanisms of action underlying the beneficial effects of cathelicidin as novel therapeutic alternatives to antibiotics.

Avian Toll-like receptor 3 isoforms and evaluation of Toll-like receptor 3-mediated immune responses using knockout quail fibroblast cells.

Toll-like receptor 3 (TLR3) induces host innate immune response on recognition of viral double-stranded RNA (dsRNA). Although several studies of avian TLR3 have been reported, none of these studies used a gene knockout (KO) model to directly assess its role in inducing the immune response and effect on other dsRNA receptors. In this study, we determined the coding sequence of quail TLR3, identified isoforms, and generated TLR3 KO quail fibroblast (QT-35) cells using a CRISPR/Cas9 system optimized for avian species. The TLR3-mediated immune response was studied by stimulating the wild-type (WT) and KO QT-35 cells with synthetic dsRNA or polyinosinic:polycytidylic acid [poly(I:C)] or infecting the cells with different RNA viruses such as influenza A virus, avian reovirus, and vesicular stomatitis virus. The direct poly(I:C) treatment significantly increased IFN-ß and IL-8 gene expression along with the cytoplasmic dsRNA receptor, melanoma differentiation-associated gene 5 (MDA5), in WT cells, whereas no changes in all corresponding genes were observed in KO cells. We further confirmed the antiviral effects of poly(I:C)-induced TLR3-mediated immunity by demonstrating significant reduction of virus titer in poly(I:C)-treated WT cells, but not in TLR3 KO cells. On virus infection, varying levels of IFN-ß, IL-8, TLR3, and MDA5 gene upregulation were observed depending on the viruses. No major differences in gene expression level were observed between WT and TLR3 KO cells, which suggests a relatively minor role of TLR3 in sensing and exerting immune response against the viruses tested in vitro. Our data show that quail TLR3 is an important endosomal dsRNA receptor responsible for regulation of type I interferon and proinflammatory cytokine, and affect the expression of MDA5, another dsRNA receptor, most likely through cytokine-mediated communication.

Collocation of avian and mammal antibodies to develop a rapid and sensitive diagnostic tool for Russell's Vipers Snakebite.

Russell's vipers (RVs) envenoming is an important public health issue in South-East Asia. Disseminated intravascular coagulopathy, systemic bleeding, hemolysis, and acute renal injury are obvious problems that develop in most cases, and neuromuscular junction blocks are an additional problem caused by western RV snakebite. The complex presentations usually are an obstacle to early diagnosis and antivenom administration. Here, we tried to produce highly specific antibodies in goose yolks for use in a paper-based microfluidic diagnostic kit, immunochromatographic test of viper (ICT-Viper), to distinguish RVs from other vipers and even cobra snakebite in Asia. We used indirect ELISA to monitor specific goose IgY production and western blotting to illustrate the interaction of avian or mammal antibody with venom proteins. The ICT-Viper was tested not only in prepared samples but also in stored patient serum to demonstrate its preliminary efficacy. The results revealed that specific anti-Daboia russelii IgY could be raised in goose eggs effectively without inducing adverse effects. When it was collocated with horse anti-Daboia siamensis antibody, which broadly reacted with most of the venom proteins of both types of Russell's viper, the false cross-reactivity was reduced, and the test showed good performance. The limit of detection was reduced to 10 ng/ml in vitro, and the test showed good detection ability in clinical snake envenoming case samples. The ICT-Viper performed well and could be combined with a cobra venom detection kit (ICT-Cobra) to create a multiple detection strip (ICT-VC), which broadens its applications while maintaining its detection ability for snake envenomation identification. Nonetheless, the use of the ICT-Viper in the South-East Asia region is pending additional laboratory and field investigations and regional collaboration. We believe that the development of this practical diagnostic tool marks the beginning of positive efforts to face the global snakebite issue.

Innate Immune Sensing of Influenza A Virus.

Influenza virus infection triggers host innate immune response by stimulating various pattern recognition receptors (PRRs). Activation of these PRRs leads to the activation of a plethora of signaling pathways, resulting in the production of interferon (IFN) and proinflammatory cytokines, followed by the expression of interferon-stimulated genes (ISGs), the recruitment of innate immune cells, or the activation of programmed cell death. All these antiviral approaches collectively restrict viral replication inside the host. However, influenza virus also engages in multiple mechanisms to subvert the innate immune responses. In this review, we discuss the role of PRRs such as Toll-like receptors (TLRs), Retinoic acid-inducible gene I (RIG-I), NOD-, LRR-, pyrin domain-containing protein 3 (NLRP3), and Z-DNA binding protein 1 (ZBP1) in sensing and restricting influenza viral infection. Further, we also discuss the mechanisms influenza virus utilizes, especially the role of viral non-structure proteins NS1, PB1-F2, and PA-X, to evade the host innate immune responses.

A high sensitivity ZENK monoclonal antibody to map neuronal activity in Aves.

The transcription factor ZENK is an immediate early gene that has been employed as a surrogate marker to map neuronal activity in the brain. It has been used in a wide variety of species, however, commercially available antibodies have limited immunoreactivity in birds. To address this issue we generated a new mouse monoclonal antibody, 7B7-A3, raised against ZENK from the rock pigeon (Columba livia). We show that 7B7-A3 labels clZENK in both immunoblots and histological stainings with high sensitivity and selectivity for its target. Using a sound stimulation paradigm we demonstrate that 7B7-A3 can detect activity-dependent ZENK expression at key stations of the central auditory pathway of the pigeon. Finally, we compare staining efficiency across three avian species and confirm that 7B7-A3 is compatible with immunohistochemical detection of ZENK in the rock pigeon, zebra finch, and domestic chicken. Taken together, 7B7-A3 represents a useful tool for the avian neuroscience community to map functional activity in the brain.

First serological evidence of West Nile virus infection in wild birds in Northern Algeria.

While the epidemiology of Flaviviruses has been extensively studied in most of the Mediterranean basin, little is known about the current situation in Algeria. In order to detect the circulation of West Nile (WNV) and Usutu viruses (USUV) in Kabylia, 165 sera were collected from two wild birds species, namely the long distance migrant Turdus philomelos (song thrush) (n = 92) and the resident Passer domesticus (house sparrow) (n = 73). A total of 154 sera were first analyzed by commercial competition ELISA. WNV and USUV micro-neutralization tests were performed on all c-ELISA positive sera and all samples with poor volume. Overall, 7.8 % (CI95 %: 3.5-11.9) were positive by c-ELISA. Positive results were detected in 12.5 % (CI95 %:5.6-19.4) of song thrushes and 1.5 % (CI95 %: 0.0-4.5) for sparrow. Micro-neutralization tests revealed an overall seroprevalence of 6.7 % for WNV (CI95 %: 2.9-10.3), Neutralizing antibodies were found in 8.7 % (CI95 %: 3.0-14.4) for song thrushes and in 4.1 % (CI95 %: 0.0-8.7) of sparrows. The current study demonstrates significant seroprevalence of WNV antibodies in wild birds in Algeria.

Study of the activation of the PI3K/Akt pathway by the motif of σA and σNS proteins of avian reovirus.

The present study was conducted to determine whether avian reovirus (ARV) activates the phosphatidylinositol 3-kinase-dependent Akt (PI3K/Akt) pathway according to the PXXP or YXXXM motifs of σA and σNS proteins. Gene splicing by overlap extension PCR was used to change the PXXP or YXXXM motifs of the σA and σNS genes. Plasmid constructs that contain mutant σA and σNS genes were generated and transfected into Vero cells, and the expression levels of the corresponding genes were quantified according to immunofluorescence and Western blot analyses. The Akt phosphorylation (P-Akt) profile of the transfected Vero cells was examined by flow cytometry and Western blot. The results showed that the σA and σNS genes were expressed in the Vero cells, and P-Akt expression in the σA mutant groups (amino acids 110-114 and 114-117) was markedly decreased. The results indicated that the σA protein of ARV activates the PI3K/Akt pathway via the PXXP motif. The results of this study reveal the mechanisms by which ARV manipulates the cellular signal transduction pathways, which may provide new ideas for novel drug targets.

Orbitally Shaken Single-Use Bioreactor for Animal Cell Cultivation: Fed-Batch and Perfusion Mode.

Increasing the cultivation volume from small to large scale can be a rather complex and challenging process when the method of aeration and mixing is different between scales. Orbitally shaken bioreactors (OSBs) utilize the same hydrodynamic principles that define the success of smaller-scale cultures, which are developed on an orbitally shaken platform, and can simplify scale-up. Here we describe the basic working principles of scale-up in terms of the volumetric oxygen transfer coefficient (kLa) and mixing time and how to define these parameters experimentally. The scale-up process from an Erlenmeyer flask shaken on an orbital platform to an orbitally shaken single-use bioreactor (SB10-X, 12 L) is described in terms of both fed-batch and perfusion-based processes. The fed-batch process utilizes a recombinant variant of the mammalian cell line, Chinese hamster ovary (CHO), to express a biosimilar of a therapeutic monoclonal antibody. The perfusion-based process utilizes either an alternating tangential flow filtration (ATF) or a tangential flow filtration (TFF) system for cell retention to cultivate an avian cell line, AGE1.CR.pIX, for the propagation of influenza A virus, H1N1, in high cell density. Based on two example cell cultivations, processes outline the advantages that come with using an orbitally shaken bioreactor for scaling-up a process. The described methods are also applicable to other suspension cell lines.

Current knowledge about interactions between avian dendritic cells and poultry pathogens.

In poultry production conditions today, birds are surrounded by viral, bacterial, and parasitic agents. DCs are the main antigen-presenting cells located in tissues of the body, and their role involves recognizing antigen structures, engulfing and processing them, and subsequently presenting antigen peptides on their surface by major histocompatibility complex, where T cells and B cells are stimulated and can begin appropriate cellular and antibody immune response. This unique function indicates that these cells can be used in producing vaccines, but first it is necessary to culture DCs in vitro to identify the principles of their interactions with pathogens. The following review summarizes our current knowledge about avian dendritic cells and their interactions with pathogens. It provides a basis for future studies of these unique cells and their use in vaccine development.