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At least 235 records · Page 13Linked to original sources
PubMed2003

Identification and molecular characterization of the RNA polymerase-binding motif of infectious bursal disease virus inner capsid protein VP3.

Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is the causative agent of one of the most important infectious poultry diseases. Major aspects of the molecular biology of IBDV, such as assembly and replication, are as yet poorly understood. We have previously shown that encapsidation of the putative virus-encoded RNA-dependent RNA polymerase VP1 is mediated by its interaction with the inner capsid protein VP3. Here, we report the characterization of the VP1-VP3 interaction. RNase A treatment of VP1- and VP3-containing extracts does not affect the formation of VP1-VP3 complexes, indicating that formation of the complex requires the establishment of protein-protein interactions. The use of a set of VP3 deletion mutants allowed the mapping of the VP1 binding motif of VP3 within a highly charged 16-amino-acid stretch on the C terminus of VP3. This region of VP3 is sufficient to confer VP1 binding activity when fused to an unrelated protein. Furthermore, a peptide corresponding to the VP1 binding region of VP3 specifically inhibits the formation of VP1-VP3 complexes. The presence of Trojan peptides containing the VP1 binding motif in IBDV-infected cells specifically reduces infective virus production, thus showing that formation of VP1-VP3 complexes plays a critical role in IBDV replication.

Amino Acid Sequence↗
PubMed1994

Host specificity of Salmonella infection in chickens and mice is expressed in vivo primarily at the level of the reticuloendothelial system.

By experimental infection, host-specific Salmonella serotypes were shown to demonstrate specificities for chickens, mice, and other laboratory animals. Following oral inoculation, four strains of Salmonella gallinarum and two S. pullorum strains, isolated from diseased poultry, were more virulent for chickens than for mice. By contrast, four strains each of S. choleraesuis and S. dublin, isolated from diseased pigs and cattle, respectively, were more virulent for mice than for chickens. These results were also reflected in the degree of virulence expressed after parenteral inoculation. In addition, S. choleraesuis, but not other serotypes, killed rats, guinea pigs, and rabbits. S. typhimurium strains varied widely in their virulence, and some strains were virulent for both mice and chickens. Four other serotypes isolated from poultry or human food poisoning cases and a nonpathogenic Escherichia coli strain were much less virulent for both experimental host species. Most of the host-specific Salmonella serotypes studied were able to colonize the distal alimentary tract and invade the tissues in both mice and chickens to various degrees. There was, however, a greater difference in the ability to survive and multiply in the visceral organs, particularly the spleen and the liver, once invasion had occurred which correlated with the virulence for the host species involved.

Animals↗
PubMedDate not supplied

Comparison of two commercial enzyme-linked immunosorbent assays and conventional methods for avian serology.

Sera tested for hemagglutination-inhibition (HI) activity against Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and virus-neutralizing (VN) activity against infectious bursal disease virus (IBDV) and viral arthritis (VA) virus were collected from a wide variety of accessions into the Diagnostic Services Laboratory, Poultry Disease Research Center, University of Georgia. The sera were then segregated according to HI or VN titer to NDV, IBV, IBDV, or VA virus and stored frozen at -20 C until tested by two commercial enzyme-linked immunosorbent assays (ELISAs). There was good correlation of mean Flockchek ELISA titers or EIA Systems sample-to-positive (S/P) ratios with specific HI or VN titers. Flockchek ELISA profile group 3 and EIA Systems mean S/P ratio of 1.12 corresponded to what were considered in our lab to be minimum protective titers for each antigen against virulent challenge in our area.

Animals↗
PubMed1998

Detection of infectious bursal disease virus of poultry in clinical samples by RT-PCR.

The RT-PCR technique was adopted to amplify variable region of VP2 gene of infectious bursal disease virus using three different sets of primers. These primers could generate products of 643, 474 and 552 bp sizes. The authenticity of the amplicons was confirmed by their size in agarose gel, restriction enzyme digestion and by nested PCR. Out of total five clinical samples tested, IBD viral genomic RNA could be detected in four by RT-PCR. Restriction enzyme digestion of PCR products with StuI could differentiate clinical samples from an intermediate vaccine strain currently being used in India.

Animals↗
PubMed1990

[Transgenic chickens].

Transgenic mice are produced by retroviral insertion, micro-injection in the early embryo, and recently by transfection of embryonic stem cells. Transgenic chickens were only made by retroviral vectors based on avian leukemia virus (ALV) and reticuloendotheliosis (REV) genomes. A replication-defective retroviral vector is preferentially used because these do not induce infectious virus. Since chickens are lacking endogenous REV sequences, a replication defective REV vector is most useful for practical application. Transgenic disease resistance is most likely obtained by blocking of viral receptors. By this approach recently transgenics with resistance against ALV infection were made at the Regional Poultry Disease Laboratory in East Lansing. Inhibition of virus replication by antisense DNA, which is complementary to viral mRNA, is promising for the future. Considerable research efforts still have to be made, however. Production of biomedical proteins will most likely be the first practical use of transgenic chickens. For the time being, vaccines will be used for the control of infectious diseases. The current live-virus vaccines will be replaced by inactivated (sub-unit) vaccines and thereafter by recombinant DNA vaccines based on viral vectors.

Animals↗
PubMed1994

Assessment of the welfare of food restricted male broiler breeder poultry with musculoskeletal disease.

The general and sexual activity of food restricted male broiler breeder poultry was assessed for evidence of behavioural changes associated with musculoskeletal lesions. The activity and fertility of male birds given betamethasone (an anti-inflammatory steroid) or saline were compared in a two-period crossover experiment. Behavioural changes occurred and the birds' mating activity and fertility were decreased when they were given the steroid, but these effects were not associated with the presence of lesions. In a second experiment, there were no differences in sexual motivation between birds either with or without leg disorders. The birds were trained to walk down an alley for their food and the speed of walking was compared in a two-period crossover experiment. Betamethasone decreased their walking speed in period one and the carryover effect was significant in period two. Naloxone decreased the walking speed of birds with lesions more than of those without lesions. This effect was taken as evidence for analgesia by endogenous opioids and may help to explain the lack of response of the birds to the analgesic agent. The evidence that these food restricted male broiler breeder birds experienced pain was equivocal.

Animals↗
PubMed1991

Environmental protection during animal disease eradication programmes.

This paper identifies animal disease eradication (ADE) programme activities which may have a negative impact on the environment. It suggests ways to lessen the impact of such activities without compromising the programme objectives. Reducing losses from livestock and poultry diseases with prevention, control and eradication programmes produces a net positive impact on the environment. An Environmental Impact Statement (EIS) should be integrated into the planning of any ADE programme. Decision-makers should give due consideration to the environmental effects of ADE programme activities, together with cost, personnel needs and other, more traditional, management concerns. A better environment will be a supplemental benefit from ADE programmes.

Animal Diseases↗
PubMedDate not supplied

[Recombinant viruses of poultry as vector vaccines against fowl plague].

To help in the control of fowl plague caused by highly pathogenic avian influenza A viruses of hemagglutinin (HA) subtypes H5 and H7 several vaccines have been developed. A prophylactic immunization of poultry with inactivated influenza viruses in non-endemic situations is questionable, however, due to the impairment of serological identification of field virus-infected animals which hinders elimination of the infectious agent from the population. This problem might be overcome by the use of genetically engineered marker vaccines which contain only the protective influenza virus hemagglutinin. Infected animals could then be unambiguously identified by their serum antibodies against other influenza virus proteins, e.g. neuraminidase or nucleoprotein. For such a use, purified HA or HA-expressing DNA vaccines are conceivable. Economically advantageous and easier to apply are modified live virus vaccines in use against other poultry diseases, which have been modified to express influenza virus HA. So far, recombinant HA-expressing fowlpox virus (FPV) as well as infectious laryngotracheitis and Newcastle disease viruses have been asssessed in animal experiments. An H5-expressing FPV recombinant is already in use in Central America and Southeast Asia but without accompanying marker diagnostics. Advantages and disadvantages of the different viral vectors are discussed.

Animals↗
PubMed2002

Isolation of myxoviruses from migratory waterfowls in San-in district, western Japan in winters of 1997-2000.

Between November 1997 and February 2000, winter migratory waterfowls of several species staying in San-in district, western Japan were surveyed for influenza A virus and paramyxovirus at four stations. A total of 18 influenza A viruses was isolated from 1,404 fecal samples of whistling swans, pintails, mallards, and white-fronted geese. Five different hemagglutinins and eight neuraminidases were identified in the viruses isolated, in 11 different combinations, including H7N8 related to a subtype of a highly pathogenic chicken virus. In 2000, five lentogenic (non-pathogenic) Newcastle disease viruses were also isolated from white-fronted geese. These results suggested that possible precursor viruses for highly pathogenic avian myxoviruses are still brought into Japan by migratory waterfowls. The results also support the contention that continued surveillance of wild waterfowl population should be an integral part of control policies for these serious poultry diseases.

Animals↗
PubMed1997

[Risk for the transmission of Newcastle disease by contaminated poultry products].

Poultry products contaminated with pathogenic strains of Newcastle disease virus are a source of virus transmission to susceptible poultry flocks. The probability of contamination varies according to the type of product. Research conducted by various laboratories in Europe has shown that pathogenic virus can be isolated from the carcasses of chickens, whether vaccinated or not, during a brief period after experimental infection. Eggs laid by hens infected with Newcastle disease virus present a very low risk. Furthermore, feathers, bones, blood and offal present potential risks if they are incorporated in poultry feed. Finally, poultry droppings used as a fertiliser can present a major risk of infection in certain circumstances.

Animal Feed↗