Chicken lines were classified into six distinct groups based on expression of B-G molecules by peripheral red blood cells (RBC). In addition to the previously reported 48 kD subunits of homodimeric B-G molecules, subunits of 60, 40, and possibly 20 kD were detected in certain of the chicken lines. Several of the chicken lines express the previously reported 40 and 44 kD subunits of heterodimeric B-G molecules; however, B21B21 chickens expressed 44 kD subunits only and B5B5 and B13B13 chickens did not express detectable levels of any heterodimeric-related molecules. These studies provide further evidence for the polymorphic nature of the B-G antigens.

Animals↗

PubMedDate not supplied

Identification of Rfp-Y (Mhc-like) haplotypes in chickens of Cornell lines N and P.

Two strains of chickens selected for differential Marek's disease (MD) resistance or susceptibility were studied for the presence of the recently described Rfp-Y major histocompatibility complex (Mhc-like) haplotypes. MD resistant chickens from line N were fixed for the classical Mhc B21 haplotype, whereas MD susceptible line P chickens were fixed for the B19 haplotype. The Rfp-Y haplotypes were identified by restriction fragment polymorphism (RFP) analysis using enzymes and Mhc probes for B-G, B-L beta II, and B-FIV. In addition an Rfp-L beta III clone was developed that differentiated Rfp-L beta from B-L beta genes. Three Rfp-Y haplotypes, defined for both class I and class II Mhc-like loci, were identified in line N (Rfp-Y5, Rfp-Y7, and Rfp-Y8) and in line P (Rfp-Y5, Rfp-Y8, and Rfp-Y9), respectively. The Rfp-Y7, Rfp-Y8, and Rfp-Y9 haplotypes have not been described previously. The Rfp-Y5 haplotype was most frequent (0.70) in line N, but existed in low frequency (approximately 0.04) in line P; the Rfp-Y9 haplotype was most frequent in line P (0.63), but was absent in line N. The Rfp-Y haplotypes-segregated in a Mendelian fashion in each line based on analysis of progeny from Rfp-Y heterozygous matings. The frequency of recombination between the Rfp-Y F and L loci was estimated to be less than 0.25%.

Animals↗

PubMedDate not supplied

Chicken developmental antigens in 15I5-B-congenic lines.

Six partially developed 15I5-B-congenic lines of chickens were used to assess the genetic influence on the developmental expression of selected epitopes of two avian developmental antigen systems: chicken fetal antigen (CFA) and chicken adult antigen (CAA). Both CFA and CAA are serologically and molecularly complex hematopoietic antigen systems, yet little is known about genetic influences on their expression. Using polyclonal rabbit anti-CFA, only slight variations in overall CFA expression on peripheral erythrocytes were observed during neonatal development; no consistent trend was evident. In contrast, analysis with monoclonal antibody 10C6 revealed that the incidence of CFA determinant 8 (CFA8) on erythrocytes of the early neonate was significantly reduced in line 15I5 compared with lines .6-2, .7-2 and .15I-5; line .C-12 also exhibited a reduced CFA8 incidence at hatching. Likewise, the CAA epitope detected by monoclonal antibody 3F12 was found to appear at a slower rate on erythrocytes from lines 15I5 and .C-12 than on those of other lines. Similar results were obtained using the anti-CAA monoclonal 4C2 where reduced expression was found in lines 15I5, .C-12, and .P-13. Results of complement-mediated cytolysis using the positive control 9F9 monoclonal antibody suggested that observed genetic differences were not due to inherent differences in erythroid cytolytic sensitivity. Neither could the results be explained by the incidence of circulating reticulocytes vs. mature erythrocytes within the lines. Rather, the results suggest that different genetic lines of chickens vary in the developmental kinetics of definitive erythrocyte subpopulations bearing specific phenotypes defined by monoclonal antibodies. These findings are discussed in light of previous observations using these B-congenic lines.

Aging↗

PubMedDate not supplied

Efficacy of Marek's disease vaccines in Mhc heterozygous chickens: Mhc congenic x inbred line F1 matings.

The goal of this study is to demonstrate that Mhc (B) heterozygous chickens differ in efficacy of response to several Marek's disease (MD) vaccines. Four types of B2 heterozygotes, in addition to B2B2 homozygotes, were developed by crossing 15.B congenic males to inbred line 7(1) (B2B2) hens. The five types of F1 chicks were intermingled in isolators and vaccinated with one of four types of MD vaccine before inoculation with the very virulent Md5 strain of MD herpesvirus. The F1 chickens differ in development of protective immunity following MD vaccination from two perspectives. First, chickens of a particular Mhc genotype were protected better by some vaccines than others. Second, individual vaccine preparations protected some Mhc genotypes more effectively. We conclude that some MD vaccines are more appropriate than others for certain B-haplotypes when chickens are heterozygous for the Mhc. The value of using Mhc-congenic x inbred line F1 animals for studies concerning the influence of the Mhc on vaccinal immunity is discussed.

Animals↗

PubMedDate not supplied

The efficacy of recombinant fowlpox vaccine protection against Marek's disease: its dependence on chicken line and B haplotype.

Earlier studies have shown that the B haplotype has a significant influence on the protective efficacy of vaccines against Marek's disease (MD) and that the level of protection varies dependent on the serotype of MD virus (MDV) used in the vaccine. To determine if the protective glycoprotein gene gB is a basis for this association, we compared recombinant fowlpox virus (rFPV) containing a single gB gene from three serotypes of MDV. The rFPV were used to vaccinate 15.B congenic lines. Nonvaccinated chickens from all three haplotypes had 84%-97% MD after challenge. The rFPV containing gB1 provides better protection than rFPV containing gB2 or gB3 in all three B genotypes. Moreover, the gB proteins were critical, since the B*21/*21 chickens had better protection than chickens with B*13/*13 or B*5/*5 using rFPV with gB1, gB2, or gB3. A newly described combined rFPV/gB1gEgIUL32 + HVT vaccine was analyzed in chickens of lines 15 x 7 (B*2/*15) and N (B*21/*21) challenged with two vv+ strains of MDV. There were line differences in protection by the vaccines and line N had better protection with the rFPV/gB1gEgIUL32 + HVT vaccines (92%-100%) following either MDV challenge, but protection was significantly lower in 15 X 7 chickens (35%) when compared with the vaccine CVI988/Rispens (94%) and 301B1 + HVT (65%). Another experiment used four lines of chickens receiving the new rFPV + HVT vaccine or CVI988/Rispens and challenge with 648A MDV. The CVI 988/Rispens generally provided better protection in lines P and 15 X 7 and in one replicate with line TK. The combined rFPV/gB1gEgIUL32 + HVT vaccines protected line N chickens (90%) better than did CVI988/Rispens (73%). These data indicate that rFPV + HVT vaccines may provide protection against MD that is equivalent to or superior to CVI988/ Rispens in some chicken strains. It is not clear whether the rFPV/gB1gEgIUL32 + HVT vaccine will offer high levels of protection to commercial strains, but this vaccine, when used in line N chickens, may be a useful model to study interactions between vaccines and chicken genotypes and may thereby improve future MD vaccines.

Animals↗

PubMedDate not supplied

An acute form of transient paralysis induced by highly virulent strains of Marek's disease virus.

A novel syndrome was observed after inoculation of 3-wk-old chickens with highly virulent Marek's disease virus (MDV) strains. This syndrome was characterized by the acute onset of neurologic signs including flaccid paralysis of neck and limbs 9-10 days postinoculation, typically resulting in death 1-3 days after the onset of clinical signs. Most affected birds died, and spontaneous recovery was rare. Few if any gross tissue changes were found. Histologic brain lesions included acute vasculitis with vasogenic edema and perivascular cuffing. The syndrome was influenced by the virus strain and dose and by chicken strain and B haplotype and was prevented by vaccination with turkey herpesvirus. Chickens up to 18 wk of age were susceptible. On the basis of clinical signs and histopathology, the syndrome was determined to be an acute form of transient paralysis (TP); its more acute nature and virtual lack of spontaneous recovery differentiated this syndrome from classical TP. Affected birds were viremic, and brains were positive for viral DNA by polymerase chain reaction assays, but these tests were also positive in inoculated chickens without clinical signs and may have limited value for diagnosis. Although acute TP should occur only rarely in Marek's disease-vaccinated commercial flocks, this syndrome may be important in laboratory studies, where it could interfere with pathogenesis trials. Finally, acute TP appears to be one component in the pathogenesis of the early mortality syndrome, a previously described immunodepressive disease induced by inoculation of 1-day-old chicks with highly virulent MDV.

Animals↗

PubMedDate not supplied

Avian leukosis virus subgroup J infection profiles in broiler breeder chickens: association with virus transmission to progeny.

Profiles of infection with avian leukosis virus subgroup J (ALV-J) and factors that predict virus transmission to progeny were studied. Eggs from an infected broiler breeder flock were hatched at the laboratory. The flock was reared in a floor pen, transferred to laying cages at 22 wk, and inseminated to produce fertile eggs. A cohort of 139 chickens was tested at frequent intervals over a 62-wk period for virus, viral antigens, or antibodies in plasma, cloacal swabs, egg albumen, and embryos. Virus was detected in 7% of chicks at hatch but spread rapidly so that virtually all chicks became infected between 2 and 8 wk of age. Mortality due to myeloid leukosis and related tumors was 22%. Over 40% of the chicks developed persistent infections, whereas the remainder experienced transient infections. Five types of infection profiles were recognized. Novel responses included hens that were positive for virus intermittently or started late in life to shed viral antigens into the cloaca. ALV-J was isolated from 6% of 1036 embryos evaluated between 26 and 62 wk. However, over 90% of the virus-positive embryos were produced between 29 and 34 wk of age. Of 80 hens that produced embryos, 21 produced at least one infected embryo and were identified as transmitters. All but one transmitter hen would have been detected by a combination of viremia, cloacal swab, and albumen tests conducted between 18 and 26 wk. However, virus was transmitted to embryos from hens that were not persistently viremic or that rarely shed viral group-specific antigen into the albumen of their eggs. Intermittent patterns of both antigen shedding and virus transmission to embryos were observed in some hens. These results validate current screening procedures to identify potential transmitter hens and provide some suggestions for improvement but also show that identification of all transmitter hens by such procedures is unlikely. Thus, eradication programs based solely on dam testing may be less effective than those where dam testing is combined with procedures to mitigate early horizontal transmission in progeny chicks.

Animals↗

PubMedDate not supplied

Influence of turkey herpesvirus vaccination on the B-haplotype effect on Marek's disease resistance in 15.B-congenic chickens.

Eight recently developed 15.B congenic lines of chickens were tested for Marek's disease (MD) resistance by intra-abdominal injection of cell-associated preparations of MD virus of a virulent strain (JM), a very virulent strain (Md5), or Md5 after vaccination with turkey herpesvirus (HVT) strain FC126. Chickens of the 15.N congenic line (B15B21 or B21B21) were very resistant to JM-induced MD, in contrast to chickens homozygous for the B-haplotypes 2, 5, 12, 13, 15, or 19. After Md5 infection, more than 88% of the chickens in all of the congenic lines developed MD. However, when chickens were vaccinated with HVT before being inoculated with Md5, the B5 and B12 homozygotes were more resistant to MD than were the B2, B13, or B19 homozygotes, and B15 and B21 homozygotes had intermediate resistance. B5B5 and B2B5 F2 chicks inoculated with HVT and Md5 had a lower prevalence of MD than B2B2 sibs. These results demonstrate that a protocol involving HVT vaccination of chicks followed by infection with very virulent MD virus will allow the detection of B-haplotypes determining MD resistance, some of which are not detectable in unvaccinated chicks challenged with virulent MD.

Animals↗

PubMedDate not supplied

Response of B congenic chickens to infection with infectious bursal disease virus.

Six congenic lines of chickens that differ from the parental inbred line RPRL-15I5 for genes in the major histocompatibility (B) complex were used to study the influence of the B haplotypes on the response of chickens to infection with virulent infectious bursal disease virus (IBDV) at 1 day or 4 weeks of age, and on the antibody response to vaccination with live or inactivated oil-emulsion (OE) IBDV vaccines at 7 weeks of age. IBDV-induced immunodepression and lesions in the bursa, spleen, and thymus in chickens infected with virus at 1 day of age were of the same degree of severity, regardless of line of chickens used. The response of blood cells to the mitogens phytohemagglutinin-M and concanavalin A was elevated in chickens infected with IBDV at 1 day of age. In an experiment conducted to study the effect of the B haplotype on IBDV infection in 4-week-old chickens, B congenic line C-12 (B12B12) showed the highest susceptibility to clinical IBD, with mortality of 79%. No detectable difference in the serological response to vaccination with live or OE IBDV vaccines was noted among chickens of various congenic lines. We conclude that the B haplotypes may influence IBDV-induced mortality, but not immunodepression or severity of lesions in lymphoid organs, or the antibody response to live or OE IBDV vaccines.

Animals↗

PubMedDate not supplied

Increase of intestinal intraepithelial lymphocytes expressing CD8 antigen following challenge infection with Eimeria acervulina.

Eimerian infection-induced changes in the intestinal intraepithelial lymphocyte (IEL) subpopulations expressing CD8 antigen (cytotoxic/suppressor T cells) or antigen-specific T cell receptor (TCR) heterodimer alpha beta (TCR2) or gamma delta (TCR1) were investigated in F2 crosses of 15I5 B-congenic chickens differing for the major histocompatibility complex (MHC). Duodenum TCR2+ IEL were increased in B2 B2 and B5 B5 chickens 7 days following secondary infection. Two-color immunofluorescence revealed that the majority of CD8+ cells in the duodenum intraepithelium of immune chickens expressed TCR2. A significant increase in the duodenum TCR2+CD8+ and TCR1+CD8+ IEL occurred in B2 B2 chickens, which developed significantly less oocyst production than the B5 B5 chickens following challenge infection. The results suggest that a significant increase in the duodenum CD8+ IEL may reflect an enhanced acquired immunity of B2 B2 chickens.

Animals↗

PubMedDate not supplied

Absence of influence on immune competence by the sex-linked gene (K) determining slow feathering in white leghorn chickens.

Males of white leghorn strain crosses heterozygous (Kk) for the sex-linked feathering locus genes were mated to rapid-feathering (k-) females to produce rapid- and slow-feathering chicks of both sexes. K did not influence humoral-mediated immunity against challenge with sheep erythrocytes, killed Brucella abortus, or killed infectious bursal disease virus. Chicks challenged at 3 weeks of age had higher primary responses and higher titers of 2-mercaptoethanol-resistant antibody (IgG) than those challenged at 1 week of age. K had no influence on levels of cell-mediated immunity based on responses in in vitro phytohemagglutinin tests of donors 2 to 126 days of age, on responses in in vitro one-way mixed-lymphocyte cultures, and on rejection rates of skin grafts on young chicks. Feathering type did not influence viremia or antibody to avian leukosis virus; the level of lymphoid leukosis tumors was higher in rapid-feathering females than in slow-feathering females at 28 weeks of age (53% vs. 72%; P less than or equal to 0.10). We conclude that K does not influence general immune competence. The possibility that it may influence specific immunity to ALV under conditions not met in this study, because of an endogenous virus recently associated with the K locus, is discussed.

Animals↗

PubMedDate not supplied

Approaches to cleaning data sets: a technical comment.

Since each of the methods described has its costs and benefits, more than one method should be used. The combination of methods helps the researcher to obtain an error-free data set. Ideally, value-to-value verification for all data sets is preferred but the multiple entry method is more efficient for large data sets. Each researcher has a definition of large and small data sets. One definition of a large data set is one containing more than 250 records. Such a definition will not be appropriate for all investigators. Therefore, each researcher should balance the allocation of resources needed for a method against the confidence required for the data.

Data Collection↗