Excretion of Histomonas meleagridis following experimental co-infection of distinct chicken lines with Heterakis gallinarum and Ascaridia galli

Background Histomonosis is a severe re-emerging disease of poultry caused by Histomonas meleagridis, a protozoan parasite which survives in the environment via the cecal worm Heterakis gallinarum. Following infection, the parasites reside in the ceca and are excreted via host feces. In the present work, male birds of conventional broiler (Ross 308, R), layer (Lohmann Brown Plus, LB) and a dual-purpose (Lohmann Dual, LD) chicken line were infected with 250 embryonated eggs of Ascaridia galli and Heterakis gallinarum, respectively, with the latter nematode harboring Histomonas meleagridis, to investigate a co-infection of nematodes with the protozoan parasite in different host lines. Methods In weekly intervals, from 2 to 9 weeks post infection (wpi), individual fecal samples (n = 234) from the chickens were collected to quantify the excretion of H. meleagridis by real-time PCR and to determine the number of nematode eggs per gram (EPG) in order to elucidate excretion dynamics of the flagellate and the nematodes. This was further investigated by indirect detection using plasma samples of the birds to detect antibodies specific for H. meleagridis and worms by ELISA. The infection with H. meleagridis was confirmed by histopathology and immunohistochemistry to detect the flagellate in the cecum of representing birds. Results The excretion of H. meleagridis could already be observed from the 2nd wpi in some birds and increased to 100% in the last week of the experiment in all groups independent of the genetic line. This increase could be confirmed by ELISA, even though the number of excreted H. meleagridis per bird was generally low. Overall, histomonads were detected in 60% to 78% of birds with temporary differences between the different genetic lines, which also showed variations in the EPG and worm burden of both nematodes. Conclusions The infection with H. gallinarum eggs contaminated with H. meleagridis led to a permanent excretion of the flagellate in host feces. Differences in the excretion of H. meleagridis in the feces of genetically different host lines occurred intermittently. The excretion of the protozoan or its vector H. gallinarum was mostly exclusive, showing a negative interaction between the two parasites in the same host. Graphic abstract

A Genetically Engineered Commercial Chicken Line Is Resistant to Highly Pathogenic Avian Leukosis Virus Subgroup J

Viral diseases remain a major concern for animal health and global food production in modern agriculture. In chickens, avian leukosis virus subgroup J (ALV-J) represents an important pathogen that causes severe economic loss. Until now, no vaccine or antiviral drugs are available against ALV-J and strategies to combat this pathogen in commercial flocks are desperately needed. CRISPR/Cas9 targeted genome editing recently facilitated the generation of genetically modified chickens with a mutation of the chicken ALV-J receptor Na+/H+ exchanger type 1 (chNHE1). In this study, we provide evidence that this mutation protects a commercial chicken line (NHE1ΔW38) against the virulent ALV-J prototype strain HPRS-103. We demonstrate that replication of HPRS-103 is severely impaired in NHE1ΔW38 birds and that ALV-J-specific antigen is not detected in cloacal swabs at later time points. Consistently, infected NHE1ΔW38 chickens gained more weight compared to their non-transgenic counterparts (NHE1W38). Histopathology revealed that NHE1W38 chickens developed ALV-J typical pathology in various organs, while no pathological lesions were detected in NHE1ΔW38 chickens. Taken together, our data revealed that this mutation can render a commercial chicken line resistant to highly pathogenic ALV-J infection, which could aid in fighting this pathogen and improve animal health in the field.

Estimation of Several Commercial, Phenotypic and Reproductive Traits' Performance, Using the Quantitative Genetic Method for Kamper Chicken Line

In this study the genetic resource of Pelung chicken from Cianjur, West Java, Indonesia, was exploited. Pelung chicken has a higher body weight growth, unique meat flavor, and superior posture, compared with other indigenous breeds. Kamper chicken line selective breeding program was conducted, to increase the performance of Pelung breed by crossing with Layer Lohmann Brown-Classic. The Layer Lohmann Brown-Classic is an imported laying-type breed, which is widely known for its reproductive performance, based on the egg productivity. This study aims to use quantitative genetic method in estimating the commercial and reproductive traits' performance of Kamper chicken line. Based on commercial, phenotypic and reproductive traits, the progenies in Kamper chicken line have significant improvements, compared to the parental cross of Pelung and Layer Lohmann Brown-Classic. The quantitative genetic method was used in describing and underlying some phenomenon, in the selective breeding program. Although quantitative genetic method is utilized in basic breeding program with significant precision and rapidness, it is only used in the preliminary study, for the advanced type. Therefore, the addition of quantitative trait loci (QTL), provide a more thorough genetic examination, and play a role in selective breeding program.

Functional genes polymorphism associations with egg quality traits in the populations of dual-purpose

Aim. To study the egg quality traits of Poltava Clay chicken line 14 and Rhode-Island Red chicken line 38 with different genotypes of the prolactin gene (PRL), growth hormone gene (GH), growth hormone receptor gene (GHR), insulin-like growth factor I gene (IGF-I) and Mx gene (Mx). Methods. The study was conducted using the method of polymerase chain reaction and restriction fragment length polymorphism analysis (PCR-RFLP). Results. We found signifi cant differences in line 14 for egg quality between prolactin, growth hormone, growth hormone receptor and Mx loci. Homozygous individuals CC and TT by prolactin locus prevailed over heterozygotes CT for egg weight on the 30th week of life. As for the growth hormone gene, the maximum differences for egg weight were revealed when comparing BC heterozygotes with CC homozygotes. As for the growth hormone receptor gene, signifi cant prevalence (p < 0.05) of individuals with the B0 genotype over A0 by parameters of egg yolk weight was noted at the age of 52 weeks. Signifi cant differences (p < 0.05) in eggshell thickness were determined for genotypes AG and GG by Mx gene in week 52. There were signifi cant differences (p < 0.05) in egg quality traits for prolactin and Mx gene for chickens of line 38. TT homozygotes by prolactin locus are characterized by the prevalence of values (p < 0.05) for the egg, yolk and shell weight. In case of Mx gene polymorphism, the heterozygous individuals were characterized by signifi cantly higher values (p < 0.05) of egg and albumen weight on the 30th week of life. There were no signifi cant differences in both experimental chicken lines for other egg quality traits between individuals with different genotypes. Conclusions. The data obtained are recommended for the use in breeding programs for Poltava Clay chicken line 14 and Rhode-Island Red chicken line 38 with the aim of obtaining microlines with the different genotypes for PRL, GH, GHR and Mx loci.