Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Birnaviridae Infections”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2006

Economically important non-oncogenic immunosuppressive viral diseases of chicken--current status.

Immunosuppressive viral diseases threaten the poultry industry by causing heavy mortality and economic loss of production, often as a result of the chickens' increased susceptibility to secondary infections and sub-optimal response to vaccinations. This paper aimed to present an up-to-date review of three specific economically important non-oncogenic immunosuppressive viral diseases of chickens, viz. chicken infectious anaemia (CIA), infectious bursal disease (IBD) and hydropericardium syndrome (HPS), with emphasis on their immunosuppressive effects. CIA and IBD causes immunosuppression in chickens and the socio-economic significance of these diseases is considerable worldwide. CIA occurs following transovarian transmission of chicken anaemia virus and has potential for inducing immunosuppression alone or in combination with other infectious agents, and is characterized by generalized lymphoid atrophy, increased mortality and severe anemia. The virus replicates in erythroid and lymphoid progenitor cells, causing inapparent, sub-clinical infections that lead to depletion of these cells with consequent immunosuppressive effects. The IBD virus replicates extensively in IgM(+) cells of the bursa and chickens may die during the acute phase of the disease, although IBD virus-induced mortality is highly variable and depends, among other factors, upon the virulence of the virus strain. The sub-clinical form is more common than clinical IBD because of regular vaccination on breeding farms. Infection at an early age significantly compromises the humoral and local immune responses of chickens because of the direct effect of B cells or their precursors. HPS is a recently emerged immunosuppressive disease of 3-6-weeked broilers, characterized by sudden onset, high mortality, typical hydropericardium and enlarged mottled and friable livers, with intranuclear inclusion bodies in the hepatocytes. The agent, fowl adenovirus-4, causes immunosuppression by damaging lymphoid tissues; the presence of IBD and CIA viruses may predispose for HPS or HPS may predispose for other viral infections. Synergism with CIA or other virus infections or prior immunosuppression is necessary to produce IBH-HPS in chickens and the susceptibility of chickens infected with fowl adenovirus varies throughout the course of CIA infection. The mechanism of immunosuppression has been studied in detail for certain chicken viruses at molecular levels, which will provides new opportunities to control these diseases by vaccination.

Adenoviridae Infections↗
PubMed1997

National surveillance of poultry diseases in Lebanon.

From 1992 to mid-1996, a national survey of poultry diseases in Lebanon was conducted. This surveillance included meat breeder, layer breeder, commercial layer and chicken broiler flocks. The history, signs, lesions and laboratory tests of poultry were used in the diagnosis of prevalent poultry diseases. Culture techniques were used to screen for bacterial diseases; serological techniques and, to a lesser extent, culture techniques were used to diagnose viral diseases; and both serological and culture techniques were used to diagnose Mycoplasma infections. The outbreaks of diseases detected in broiler breeder flocks and the number of such flocks experiencing these diseases were as follows: femoral head necrosis (6), egg-drop syndrome (3), reovirus-associated malabsorption syndrome (3), synovitis (Mycoplasma synoviae infection) (7), swollen head syndrome (SHS) (3), tenosynovitis (viral arthritis) (1), lymphoid leukosis (3), avian encephalomyelitis (1), fowl pox (1) and aortic rupture (1). The disease outbreaks detected in layer breeders were as follows: SHS (2), bumble foot (2), egg-drop syndrome (3) and avian infectious bronchitis (IB) (1). The disease outbreaks detected in commercial layer flocks were as follows: egg-drop syndrome (5), avian infectious laryngotracheitis (2), avian IB (nephrogenic strain) (1), malabsorption (1), avian tuberculosis (Mycobacterium avium) (1), Marek's disease (1), fowl pox (1), Salmonella enterica subsp. enterica Enteritidis infection (1), salpingitis (1) and Heterakis gallinae infestation (1). The disease outbreaks detected in broiler flocks were as follows: colibacillosis (40), infectious bursal disease (Gumboro disease) (15), malabsorption syndrome (8), avian infectious laryngotracheitis (8), paratyphoids (salmonellosis) (7), femoral head necrosis (8), SHS (6), avian mycoplasmosis (Mycoplasma gallisepticum infection) (6), synovitis (7), avian IB (6), botulism (1), avian encephalomyelitis (1) and gangrenous dermatitis (1). Diseases which occurred and which were reported for the first time in Lebanon were as follows: bumble foot, femoral head necrosis, avian IB (nephrogenic strain), malabsorption syndrome and SHS. This surveillance helped to establish baseline data concerning the predominant poultry diseases in Lebanon. Such information is a prerequisite for future regional and international collaboration to identify the source of the aetiological agents and to control their spread to neighbouring countries.

Adenoviridae Infections↗
PubMedDate not supplied

Proliferation of lung macrophages in acute fatal viral infections in chickens.

Marked proliferation of macrophages engulfing yellow pigments and fragmented erythrocytes were seen in the air capillaries and blood capillaries of the lungs of chickens affected with acute fatal viral hydropericardium syndrome, highly pathogenic infectious bursal disease, and highly pathogenic avian influenza. Proliferation of lung macrophages was associated with systemic proliferation of macrophages. Acute destruction of erythrocytes in these infections may have induced systemic hyperplasia of macrophages. The acute and severe proliferation of lung macrophages may cause acute respiratory dysfunction and be one of the factors inducing mortality in infected chickens. This syndrome may be categorized as "virus-associated hemophagocytic syndrome."

Acute Disease↗
PubMed1998

Protection of broiler breeders by an inactivated combined water-in-oil-in-water viral vaccine.

A four-component vaccine, prepared by combining the single vaccines, contains subunits of Newcastle disease and infectious bronchitis viruses, as well as whole inactivated infectious bursal disease and egg drop syndrome viruses. The vaccine is prepared in the form of a low-viscosity water-in-oil-in-water emulsion with low mineral oil content. Heavy breeders were vaccinated at the age of 20 weeks by intramuscular administration of 0.5 ml vaccine/bird in an experiment carried out under field conditions, involving 5000 female and 450 male parents. The birds had previously been vaccinated with live vaccines according to an obligatory field vaccination programme. Vaccination with the WOWE vaccine near the point of lay elicited serological responses protecting both the parents and their progeny. Each of the antigens administered in the four-component vaccine was as effective as the respective single component vaccine. The mortality, recorded during the 31-week experimental period, was 6.2%. Mortality and morbidity were not triggered by viruses against which vaccination was carried out. Egg production was not affected by the vaccination and was 170.2 eggs per hen during the 28-week production period.

Adenoviridae Infections↗
PubMed2005

Intracellular interference of infectious bursal disease virus.

A search for dominant-negative mutant polypeptides hampering infectious bursal disease virus (IBDV) replication has been undertaken. We have found that expression of a mutant version of the VP3 structural polypeptide known as VP3/M3, partially lacking the domain responsible for the interaction with the virus-encoded RNA polymerase, efficiently interferes with the IBDV replication cycle. Transformed cells stably expressing VP3/M3 show a significant reduction (up to 96%) in their ability to support IBDV growth. Our findings provide a new tool for the characterization of the IBDV replication cycle and might facilitate the generation of genetically modified chicken lines with a reduced susceptibility to IBDV infection.

Birnaviridae Infections↗
PubMed2006

Nonstructural protein of infectious bursal disease virus inhibits apoptosis at the early stage of virus infection.

Infectious bursal disease virus (IBDV), the causative agent of a highly contagious disease in chickens, carries a small nonstructural protein (NS). This protein has been implicated to play a role in the induction of apoptosis. In this study, we investigate the kinetics of viral replication during a single round of viral replication and examine the mechanism of IBDV-induced apoptosis. Our results show that it is caspase dependent and activates caspases 3 and 9. Nuclear factor kappa B (NF-kappaB) is also activated and is required for IBDV-induced apoptosis. The NF-kappaB inhibitor MG132 completely inhibited IBDV-induced DNA fragmentation, caspase 3 activation, and NF-kappaB activation. To study the function of the NS protein in this context, we generated the recombinant rGLS virus and an NS knockout mutant, rGLSNSdelta virus, using reverse genetics. Comparisons of the replication kinetics and markers for virally induced apoptosis indicated that the NS knockout mutant virus induces earlier and increased DNA fragmentation, caspase activity, and NF-kappaB activation. These results suggest that the NS protein has an antiapoptotic function at the early stage of virus infection.

Animals↗
PubMed2006

Effect of infectious bursal disease virus insult on iron, copper, and zinc concentration in liver, bursa of Fabricius, spleen, pancreas, and serum of chickens.

The effect of a systemic disease on the dynamics of iron, zinc, and copper in chickens fed ad libitum was examined by infecting 10-day-old specific pathogen-free chickens with infectious bursal disease virus (IBDV). Liver, bursa of Fabricius, pancreas, spleen, and serum were sampled in 10 controls and 10 challenged chickens at 3-day intervals postinfection (PI) for 15 days. The samples were analyzed using atomic absorption spectroscopy. Serum levels were similar to that reported in the literature. Concentrations of iron and zinc did not change significantly in the pancreas, but there was an increase in copper in infected pancreatic tissue on days 9 and 15 PI. Iron concentration in the spleen showed a significant increase on days 6, 9, and 15 PI, whereas zinc was only significantly increased on day 15 PI. There was no significant change in copper concentrations in the spleens of infected chickens vs. controls. This finding is in line with previously reported data. The results showed that the liver was not a major tissue where iron and zinc were sequestered, as previous data have shown in mammals. Instead, the bursa of Fabricius had significantly increased levels of both iron and zinc in infected tissue vs. control tissue from 9 days PI on. Furthermore, the bursa had increased levels of copper in the latter portion of the study. These findings suggest that the bursa of Fabricius rather than the liver is the major organ for metallic ion sequestering during IBDV infection.

Animals↗
PubMed1995

Influence of subclinical virus infections and other factors on broiler flock performance.

1. The influence of subclinical infections with infectious bursal disease virus, adenoviruses, REO viruses and chicken anaemia virus and of various production variables on broiler flock performance was investigated. 2. A significant effect could not be demonstrated of any of the viral infections either alone or in combination. 3. The production results were profoundly influenced by several other factors, that is, breed, diet, stock density and contents of whole wheat grain in the food. 4. The incidence of horizontally-transmitted subclinical chicken anaemia virus infection in Danish broilers has decreased significantly during the period 1988-89 to 1992-93, probably because of improved hygiene and management. The incidence of adeno- and REO virus infections did not change during the same period. 5. It is concluded that factors other than subclinical viral infections presently have an economic impact on performance observed in the Danish broiler production.

Adenoviridae Infections↗
PubMedDate not supplied

Apoptosis in cell cultures induced by infectious bursal disease virus following in vitro infection.

Chicken embryo fibroblasts (CEFs) and Vero cells infected with infectious bursal disease virus (IBDV) exhibited the biochemical feature of apoptosis. Agarose gel electrophoresis of DNA extracted from IBDV-infected cells revealed the characteristic laddering pattern of DNA fragmentation, which was more intense in infected CEFs than in Vero cells. The appearance of apoptotic nucleosomal DNA fragments in IBDV-infected CEFs was independent of virus replication and occurred at an early stage following in vitro infection.

Animals↗
PubMed1998

Effect of immunostimulation on cytotoxic activity of intestinal intraepithelial lymphocytes of chickens in infectious bursal disease and Eimeria tenella infections.

In chickens, intestinal intraepithelial lymphocytes (iIELs) exhibit spontaneous natural killer (NK) cell like activity, by which they are active in the first line of defence on gut epithelial linings. In the present study, the cytotoxic activity of iIELs was found to be drastically suppressed in chickens experimentally infected with infectious bursal disease (IBD) virus at the age of 5 weeks and also in chickens experimentally infected with Eimeria tenella oocysts at the age of 8 weeks (p < 0.01). As nonspecific immunostimulation is gaining importance, immunostimulants such as immunostimulating Mycobacterium phlei (ISMP) and bone marrow culture supernatant (BMCS) were tested for their influence on the functional activity of iIELs of chickens in IBD and E. tenella infections. In chickens primed with ISMP a week prior to respective experimental infections, it was found that the cytotoxic activity of iIELs was restored (p < 0.01) in both IBD and E. tenella infections. At the same time, in chickens primed with BMCS a week prior to respective experimental infections, the cytotoxic activity of iIELs was restored to a certain extent (p < 0.01) in E. tenella but not at all in IBD infection. These results showed that application of immunostimulation helped potentiate and restore the functional activity of iIELs of chickens in IBD and E. tenella infections.

Animals↗
PubMed2006

B subunit of E. coli enterotoxin as adjuvant and carrier in oral and skin vaccination.

Mucosal sites are one of the main natural ports of entry into the body. Stimulation of a local response by antibodies as the systemic protection may enhance the efficacy of non-living vaccines, and allow for vaccination by subunit vaccines without the need for injection. Mucosal or skin vaccination necessitates a suitable adjuvant and carrier. Escherichia coli heat-labile enterotoxin (LT) and its B subunit (LTB) have been found to be effective adjuvants. The aim of this study was to efficiently produce and purify recombinant LTB (brLTB), and examine its adjuvant and carrier properties. The gene encoding LTB was cloned and expressed in E. coli, and the product was found to have a pentameric form with the ability to bind the cell receptor, GM1 ganglioside. A one-step method for efficient purification and concentration of brLTB was developed. Both oral and intramuscular vaccination with purified brLTB yielded high antibody titers, which detected the whole toxin. In an attempt to test its adjuvant characteristics, brLTB was mixed with either BSA or a recombinant protein (rKnob of egg drop syndrome adenovirus) and delivered intramuscularly, orally or transcutaneously. The addition of brLTB significantly elevated the antibody response in groups vaccinated orally and transcutaneously, but had no influence in injected groups. Vaccination with another recombinant protein, (viral protein 2 of infectious bursal disease virus) supplemented with brLTB did not elevate the antibody response, as compared to vaccination with the antigen alone. These results demonstrate that the addition of brLTB makes oral and transcutaneous vaccination with protein antigens possible.

Adenoviridae Infections↗
PubMed2000

Measuring infectious bursal disease virus RNA in blood by multiplex real-time quantitative RT-PCR.

A quantitative reverse transcription polymerase chain reaction (RT-PCR) protocol for assessing infectious bursal disease virus (IBDV) RNA levels in blood was developed using the ABI PRISM 7700 Sequence Detection System coupled with TaqMan chemistry. To control for variations in sampling and processing between samples 28S rRNA was co-amplified in a multiplex reaction and used to quantify total RNA. Relative quantification and standardisation was achieved using a log10 dilution series of RNA extracted from IBDV stock. A linear relationship was observed between input RNA and cycle threshold values (C(T)) over 5 log10 dilutions for the IBDV-specific product and 6 log10 dilutions for the 28S rRNA-specific product. As a test of the assay it was used to determine whether differences in susceptibility to IBDV observed between inbred lines of chickens could be detected at the level of viral load in the blood. Viral RNA levels peaked 2 days post-infection when there was significantly less viral RNA in the blood of resistant line 6(1) chickens compared with the more susceptible Brown Leghorns (P = 0.01). These results demonstrate that the course of IBDV infection can be monitored by quantifying IBDV RNA extracted from blood of infected chickens using TaqMan technology.

Animals↗
PubMedDate not supplied

The exacerbating effect of infectious bronchitis virus infection on the infectious bursal disease virus-induced suppression of opsonization by Escherichia coil antibody in chickens.

Chickens infected with infectious bronchitis virus (IBV) and infectious bursal disease virus (IBDV) commonly develop secondary infection of the respiratory tract with Escherichia coli, resulting in significant economic losses. To understand the host factors that may contribute to the E. coli infection, we investigated macrophage-mediated E. coli phagocytosis, intracellular bacterial killing, and development of opsonizing antibody in previously uninfected chickens and in those infected with IBV, IBDV, and IBDV plus IBV. Macrophages from the peripheral blood and the respiratory tracts of chickens infected with IBV or IBDV plus IBV efficiently performed in vitro phagocytosis of E. coli in the presence of positive-control serum (i.e., E. coli antiserum produced in normal chickens). Those macrophages also had adequate bactericidal activity, indicating that IBV and IBDV infections had not affected their phagocytic activity or bactericidal function. The phagocytic activity of macrophages remained unaffected (P < 0.05) when the positive-control serum was replaced with E. coli antiserum produced in chickens infected with IBV alone. However, when E. coli antisera raised in IBDV-infected and, especially, that produced in IBDV plus IBV-infected chickens were supplemented, the percentage of phagocytosis and number of bacteria ingested per phagocyte were significantly (P < 0.05) less. These results indicate that although IBDV alone has the potential to markedly reduce opsonizing ability of antibody, this effect is significantly (P < 0.05) exacerbated by IBV infection.

Animals↗
PubMedDate not supplied

Simplified sample processing combined with a sensitive nested polymerase chain reaction assay for detection of infectious bursal disease virus in the bursa of Fabricus.

A rapid and sensitive protocol for the detection and amplification of infectious bursal disease virus (IBDV) RNA in the bursa of Fabricius was developed. By digestion with proteinase K and subsequent extraction with phenol and chloroform, IBDV RNA was efficiently released from a single bursa. IBDV RNA extraction time was shortened to 4 hr, compared with 24 hr with the traditional method, and only one bursa was needed instead of five. This more simplified procedure resulted in a significant reduction in costs due to less labor and the reduction in expensive chemicals and reagents. Four primers were selected from the sequence of a hypervariable region in VP2 genes. For the amplification of genomic IBDV RNA, the product (643 bp) of reverse transcriptase-polymerase chain reaction (RT-PCR) was reamplified and double checked by a nested PCR amplifying a 491-bp cDNA. The sensitivity of nested PCR was at least 100 times greater than RT-PCR as determined by dilution of the bursal homogenate. The fidelity of the nested PCR product was confirmed by Southern blotting, demonstrating specificity to the VP2 gene of IBDV. The simplified sample processing, shortened procedure time, and technical ease of this nested PCR render it more suitable for implementation in routine RT-PCR with restriction fragment length polymorphism testing for the detection and differentiation of IBDV RNA, especially for studies of IBDV infections of individual chickens.

Animals↗
PubMed1999

Lysis of myelocytes in chickens infected with infectious bursal disease virus.

In specific-pathogen-free chickens infected with the highly virulent HPS-2 strain or virulent reference GBF-1 strain of infectious bursal disease virus (IBDV), pathologic changes of the bone marrow were investigated. On histologic examination, bone marrow lesions were prominent in the HPS-2 group but only mild in the GBF-1 group. The bone marrow of the HPS-2 group showed severe lysis and depletion of heterophil myelocytes with pyknotic nuclear alteration 2-3 days after inoculation. On examination with an electron microscope, heterophil myelocytes were characterized by shrinkage of the cytoplasm and peripheral condensation of nuclear chromatin. IBDV particles were not detected in altered myelocytes. A terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling method demonstrated a positive reaction in only heterophil myelocytes. In contrast, nucleosomal DNA fragmentation in HPS-2-infected bone marrow cells was indiscernible by agarose gel electrophoresis. These findings indicate that lysis of bone marrow cells is selectively induced in heterophil myelocytes at an early stage after IBDV infection and independent of virus replication.

Animals↗
PubMed2006

Passive immunization using purified IgYs against infectious bursal disease of chickens in Pakistan.

Infectious bursal disease (IBD) is an acute and highly contagious disease of young chickens caused by Birnavirus. Mortality of infected birds can be best prevented if injected with antibodies. The present study was an attempt to raise specific hyper-immune polyclonal antibodies against IBD virus in Pakistan. Commercial layers divided into four groups were injected with IBD vaccine subcutaneously according to four different treatment regimens. Eggs were collected daily and antibodies were purified from yolk with dextran sulphate. Titers of antibodies in serum and yolk were evaluated with enzyme linked immunosorbant assay and agar gel precipitation test. Antibody titers were significantly higher in yolk than serum. Eggs collected at 28 days post-vaccination had maximum antibody titers. Of treatment regimens, T3 was found to be most effective for hyperimmunization. Lyophilized antibodies stored at 4 degrees C did not lose their activity till the end of experiment. IBD virus infected birds were injected with purified antibodies which induced 92% recovery as compared to control birds. The study implicates that the purified antibodies may be useful as a therapeutic agent to cure IBD infected birds.

Animals↗