In ovo vaccination technology

More than 80% of the U.S. broiler industry has converted to the in ovo vaccination process for control of Marek's disease. Providing certain criteria are met, including timing and site of vaccine placement, vaccine mixing, machine sanitization, and hatchery management specifications, this has proven to be an efficacious and convenient method of vaccination. Efforts to extend the technology for other viral vaccines including Newcastle, bronchitis and bursal disease, and bacterial and parasitic vaccines are in progress. Collectively, these studies demonstrate that in ovo vaccination technology using approved vaccine is a safe, efficacious, and convenient method for vaccination of poultry.

Applications in in ovo technology

By mid-August 1995, 55% of broiler embryos in North America were vaccinated for Marek's disease using the INOVOJECT system, with 201 INOVOJECT machines placed with 16 of the top 25 poultry producers, providing the industry with the capacity to inject in excess of 400 million eggs per month or about 5 billion eggs per annum. In ovo administration of a bursal disease antibody-infectious bursal disease virus (BDA-IBDV) complexed vaccine to specific-pathogen-free (SPF) embryos was safer and more potent than conventional IBDV vaccine alone because it delayed the appearance of bursal lesions, produced no early mortality, produced higher geometric mean antibody titers against IBDV, and generated protective immunity against challenge. In ovo administration of a BDA-IBDV complexed vaccine to broiler embryos generated antibody titers against IBDV sooner than conventional virus vaccinates, and generated protective immunity against challenge Direct DNA injection of plasmid DNA encoding beta-galactosidase into breast muscle in ovo and posthatch was an effective means to achieve both gene transfer and expression, with potential for the development of gene vaccines using plasmids encoding protective antigens from poultry pathogens. In ovo administration of 800 U chicken myelomonocytic growth factor (cMGF), a chicken hematopoietic cytokine for cells of the monocytic-granulocytic lineages, significantly reduced mortality associated with Escherichia coli exposure within the hatcher when compared to PBS controls (6.1 vs 12.4, P < or = 0.05), but not when compared to a yeast expression control. A procedure was developed enabling injection prior to the onset of incubation without compromising embryo viability. This in ovo injection process has opened up the window of embryo development during incubation for intervention, as illustrated by the 100% male phenotype produced in chicks hatching from eggs injected with aromatase inhibitor prior to incubation. These data illustrate some of the in ovo applications presently in use by the poultry industry, and under development or in research at EMBREX.

Evaluation of the humoral immune response to different antigens in Arkansas Regressor and Progressor chickens

Arkansas Regressor and Progressor chickens were re-evaluated for their immune response to different antigens. Chickens received i.v. injection of either SRBC (10 birds per line) or Salmonella pullorum (SP; 10 birds per line) at 7 wk of age, and sera were collected at 6, 13, and 20 d postimmunization. A third group of birds (10 birds per line) received and i.m. injection of GAT emulsion at 7 and 12 wk of age, and sera were collected at 10 and 14 wk of age. There were significant differences between the two lines in their humoral immunity to SRBC, SP, and GAT. Such results suggest genetic control of humoral immunity to these antigens in these lines. It is unknown whether humoral immunity to these antigens is correlated to regression of tumors induced by Rous sarcoma virus.

Action spectrum of antiviral factor from chicken sera

Rous sarcoma virus infections of regressor line chickens stimulate the transient production of antiviral factors in the serum. Earlier the present authors reported that a viral neutralization factor (VNF) inactivated Rous sarcoma virus during a 3-h incubation. The VNF is likely to have a broad antiviral and antimicrobial spectrum because it is active against several unrelated pathogenic poultry viruses. The present study measured the activity of VNF against Newcastle disease virus, infectious bursal disease virus, and infectious bronchitis virus. The VNF is active in immunologically incompetent systems and must be preincubated with the virus in order to inhibit it. Based upon the current experiments, it is proposed that VNF is not an immunomodulator but directly inactivates the virus. The VNF agent appears to be one of a newly identified class of nonspecific antiviral agents produced in vivo in chickens in response to a viral infection.

Amino acid sequence of a globin from the sea cucumber Caudina (Molpadia) arenicola

Coelomic cells from the sea cucumber Caudina (Molpadia) arenicola contain four major globins, A, B, C and D. The hemoglobins from this organism show unusual ligand-linked dissociation properties. The complete amino acid sequence of the D globin has been established. It is N-acetylated, consists of 158 residues and has a 10 amino acid N-terminal extension similar to that found in some other invertebrate globins. The C. arenicola D globin has an equal sequence identity (28%) with both alpha and beta human globins and as anticipated, is more closely related to these vertebrate proteins than are molluscan globins. The C. arenicola D globin shows a 59% identity with the globin I from the sea cucumber Paracaudina chilensis. The availability of the C. arenicola D globin sequence will aid the X-ray analysis of this protein and facilitate an understanding of the changes in subunit interactions that occur with cooperative ligand binding.

Stimulation of progressor and regressor chicken leukocytes with Con A, PHA-P, and Rous sarcoma tumor antigens

Progressor (Pr) and regressor (R) chickens from the University of Arkansas lines were used as leukocyte donors. Peripheral blood leukocytes were stimulated with two mitogens, concanavalin A (Con A) and phytohemagglutinin-P (PHA-P). Both Pr and R leukocytes displayed the same Con A-stimulated dose dependency on blastogenesis. The regressor leukocytes were stimulated more than the progressor leukocytes at high concentrations of PHA-P. There did not appear to be any correlation between the response of individual chickens to mitogens and their ability to regress a Rous sarcoma. We concluded that the R-Rs-1 gene, which controls the animal's response to Rous sarcoma, and the Con A and PHA-P response genes are probably located at different loci in the chicken genome. Mitogen-induced blastogenesis does not appear to be a useful index to predict regression response in the chicken. Under our experimental conditions, regressor leukocytes showed a sensitization to sarcoma antigens, but the progressor leukocytes did not. The data suggest that the R-Rs-1 gene does not confer a generally enhanced immune status to the chicken but acts as an Ir response gene to augment the immune response to specific antigens.