Intraembryonic avian leukosis virus subgroup C (ALV-C) inoculation producing wasting disease in ducks soon after hatching.

We have studied the pathogenic changes in Khaki Campbell ducks injected in mid embryogenesis with ALV subgroup C virus td daPR-C derived from a molecular clone. The employed duck flock was shown to be highly genetically homogeneous and was controlled for the absence of current infections. Clear symptoms of wasting disease, which appeared since one week post hatching, represented the early consequence of the virus infection. They were manifested by decreased body weight, including clear involution of thymic tissue and pronounced anaemia. Microscopically, thymuses of infected animals displayed lymphatic depletion, clearly visible in the lobular cortex. Similarly, in the bursa Fabricii follicles, a marked reduction of the cortical layer and a decrease in folicullar centres was revealed. A decrease in the antibody response correlated with bursa Fabricii atrophy. The clear signs of anaemia were confirmed by haematological measurements, red blood cell count, haematocrit value and haemoglobin included. On the basis of these and additional observations we propose that inoculation of duck embryos provides a suitable model for analysis of the wasting disease produced by ALV-C.

Effects of 1,2-dibromoethane on haematopoiesis in the chick embryo.

1. Chick embryo in ovo was used to investigate the effects of 1,2-dibromoethane (DBE) on haematopoiesis at a developmental stage where the primitive erythroid cells divide and differentiate in circulation. 2. Early after DBE treatment on embryonic day 3, annexin V/propidium iodide labelling showed acute cell death of erythroid elements, which was subsequently compensated for by the release of immature cells into the circulation. Simultaneously, the comet assay indicated increased DNA damage in DBE-exposed blood cells when compared with controls. 3. After embryonic day 5, there was no indication for ongoing prominent cell death in the DBE-treated group. However, the DNA damage assessed by the comet assay persisted until embryonic day 10 in the peripheral blood cells, and for even longer in cells from thymus and bursa. 4. The kinetics of DNA fragmentation in both erythroid and lymphoid cells implied genotoxic damage by DBE to the stem cells of the definitive elements and transmission of this damage through the successive cell generations. 5. The early chick embryo provides a suitable alternative to mammalian models for investigation of long-term effects of xenobiotics on haematopoiesis.

Amyloid A amyloidosis in non-infected and avian leukosis virus-C persistently infected inbred ducks.

The breeding history of the first inbred strain of Khaki Campbell ducks is presented. The genetic homogeneity of this strain was tested on the basis of serum amyloid A (SAA) polymorphism and it was established that it harbours only the SAA allele A, which is expressed in liver, lung and bursa of Fabricius tissues. Pathogenic changes in control and avian leukosis virus-C (ALV-C) persistently infected ducks were evaluated during the period spanning 1 to 10 months after hatching. In both groups, AA amyloidosis was revealed and characterized. In spite of the inbred nature of animals, the incidence of amyloid A deposition varied among experiments, suggesting that additional non-genetic factors are involved. Similar variation was found in ALV-C persistently infected ducks, where only in one out of three experiments was the incidence ofAA amyloidosis significantly higher than in controls.

Prague inbred lines of chickens: a biological model for MHC research.

Evidence for further complexity of the genetic structure of chicken major histocompatibility complex (B) is reviewed, with a historical account showing mutual dependence of the development of an animal genetic model and the growth of scientific knowledge concerning the chicken MHC.

B (MHC) antigen dependent modulation of GvH reactivity by neonatal thymectomy and alloimmunization.

Using Prague recombinant congenic lines of chickens, we found that neonatal thymectomy led either to a marked suppression (CC donors) or to a transient increase (CB donors) of GvH response against the B-F/L + B-G and B-F/L disparate congenic embryos. Similarly, preimmunization with the B (MHC) different blood led either to the suppression or increase of GvH reactivity of the CC and CB line donors depending on the antigenic difference (B-F/L + B-G, B-F/L, B-G) between the blood used for preimmunization, the immunized donor for GvH splenomegaly assay and the recipient embryos. In all cases, the suppression of GvH response of the CC line donors is accompanied with a marked increase in GvH reactivity against syngeneic and B-G 12 disparate embryos, suggesting an autoimmune state. Furthermore, the CC line chickens suffering from GvHD had lower GvH reactivity against the B (MHC) different embryos and a significantly raised reactivity against syngeneic embryos in comparison with controls. Chickens of the same group recovering from GvHD had an extremely high alloreactivity and only slightly or no increased GvH reactivity against syngeneic embryos.

Test of prolongation of skin graft survival by blood injections provides evidence for presence of a new histocompatibility locus in the B-G region of chicken MHC.

When used for pretransplantation treatment, blood of congenic chicken lines CB and CB.R1, incompatible only in the B-G region of the major histocompatibility complex (MHC), differed in their ability to induce prolonged survival of skin grafts transferred from either of these lines onto recipients of a third congenic line, CC. Moreover, skin grafts from CB and CB.R1 donors displayed a difference in survival time, irrespective of blood pretreatment. Graft survival time after pretreatment of recipients with CB blood could be prolonged by prior induction of neonatal tolerance to the B-G product; this could be done with injections of whole blood or of separated erythrocytes or leucocytes of line CC.R1 chickens (incompatible with CC recipients in the B-G region). The results indicate that a new histocompatibility locus is present in the B-G region of the chicken MHC.

Differences in the prolongation of skin graft survival by pretransplant blood injections in the model system of congenic lines of chickens.

The effect of pretransplant donor-specific blood injections on the survival of subsequent skin grafts was studied in the group of congenic chicken lines (CB, CC, CB.R1, CC.R1, CC.R2) disparate at the major histocompatibility complex (B complex) haplotype or at its individual regions (B-F and B-G). Different combinations of blood and skin donors and recipients were tested that were disparate either at the B-F region or at combined B-F and B-G regions. Significant differences between individual lines were found. In CC (B4) recipients, survival times of CB.R1 (B12r1, B-F disparity) and CB (B12, B-F + B-G disparity) skin grafts were prolonged by injections of CB.R1 blood, but not of CB blood. In CB recipients, the survival of CC.R1 (B4r1, B-F disparity) and CC (B4, B-F + B-G disparity) skin grafts was also prolonged by pretreatment with CC.R1 blood, albeit less prolonged than in CC recipients. The recipients from the recombinant lines CB.R1 and CC.R1 responded differently. In CB.R1 recipients, the survival of only CC.R1 grafts was prolonged by the injection of CC.R1 blood (B-F + B-G disparity). In CC.R1 recipients, differences between pretreatment with CB blood (B-F disparity) and CB.R1 blood (B-F + B-G disparity) and between survival times of CB and CB.R1 skin grafts were not found. The observed differences in graft survival may be due to the strength of antigenic difference between B-F4 and B-F12 products and to the different cooperation of B-F and B-G region antigens in the recombinant haplotypes.

Syngeneic lines of chickens. VII. The lines derived from the recombinants at the B complex (MHC) of Rous sarcoma regressor and progressor inbred lines of chickens.

Based on recombinants between the B haplotypes of chickens of inbred lines CB, CC, and CB.I-B7, three new inbred lines homogeneous in transplantation and erythrocyte antigens were established by backcrossing. These newly established recombinant lines, CB.R1, CC.R1, and CC.R2, together with the original inbred lines, which differ at the B complex (MHC) and in the degree of genetically controlled resistance to progressive growth of RSV-induced tumours, represent a model system for study of the structure of the B complex and of the functions of individual B regions in the control of carcinogenesis.

Effect of B-G region of the MHC on skin graft survival in chickens treated by injections of whole blood.

CC (B4/B4) chickens exhibited prolonged skin graft survival when pretreated by injections of whole blood from CB.R1 (B12.r1/B12.r1) donors. The difference in survival time was statistically significant between grafts from CB.R1 donors and from CB donors, differing only at the B-G region product. Pretreatment with CB blood (B12/B12) had no effect on graft survival. The results indicate that B-G region of the MHC has an effect on histocompatibility in the chicken system used.

Interstrain differences in the reactivity of normal mouse sera against erythrocyte surface antigens of inbred chicken lines.

Normal mouse sera from non-immunized individuals of different strains gave high titres of "natural" antibodies which agglutinated RBC's of different inbred lines of chickens. Normal mouse sera of A strain and its congenic lines agglutinated RBC's of all chicken lines whereas normal sera of B10 strain and its congenic lines did not react with RBC's of Iowa A line. Normal sera of other mouse strains behaved similarly. The different reactivity of the congenic chicken lines IA and IC, which are identical in the B complex (MHC) and differ only in erythrocyte antigens of the A blood group system, suggests that natural antibodies may also react with antigens other than the chicken MHC antigens. On the other hand, normal sera from chickens of inbred lines reacted with all erythrocytes of the different mouse strains tested.

A spontaneous chicken chimaera with serologically and morphologically different types of erythrocytes.

Among hybrids of the inbred chicken lines, cock 1357 was found to be chimaeric in red blood cells. This cock possessed three serologically distinct types of erythrocytes and two types different in shape and size.

Analysis of the alloimmune properties of a recombinant genotype in the major histocompatibility complex of the chicken.

In a population of (CB X CC)F1 X WB hybrids, a chicken was found with a presumably recombinant haplotype, BR1, whose antigenic products detectable by hemagglutination contained determinants derived from both parental haplotypes, i.e. B1 (from CB) and B2 (from CC). This recombinant bird and its progeny from different crosses were tested by skin grafting, graft-vs.-host (GVH) and mixed lymphocyte reactions (MLR). The results define two regions of the B system, the B-F and the B-G. The B-F region determined serologically defined antigens, histocompatibility antigens, and controlled the GVH and MLR reactions, while the B-G region was responsible only for synthesis of serologically detectable antigens.