Pathological Changes in Natural Infection of Pheasants with Highly Pathogenic Avian Influenza A (H5N8) in Bulgaria.

INTRODUCTION: The study of histopathological changes caused by influenza A (H5N8) viral infection in bird species is essential for the understanding of their role in the spread of this highly infectious virus. However, there are few such studies under natural conditions in minor gallinaceous species. This article describes the pathomorphological findings in Colchis pheasants infected naturally with H5N8 during an epizootic outbreak in Bulgaria. MATERIAL AND METHODS: Samples of internal organs of 10 carcasses were collected for histopathological and immunohistochemical evaluation, virus isolation and identification, and nucleic acid detection. RESULTS: Consistent macroscopic findings were lesions affecting the intestine, heart, lung, and pancreas. Congestion and mononuclear infiltrate were common findings in the small intestine, as were necrosis and lymphoid clusters in the lamina propria of the caeca. Congestion with small focal necrosis and gliosis with multifocal nonpurulent encephalitis were observed in the brain. Myocardial interstitial oedema and degenerative necrobiotic processes were also detected. Immunohistological analysis confirmed systemic infection and revealed influenza virus nucleoprotein in all analysed organs. CONCLUSION: Variable necrosis was observed in the brain, liver, trachea, heart, small intestine, and caeca. Viral antigen was commonly found in the brain, heart, lung and trachea. Contact with migrating waterfowls was suspected as a reason for the outbreak.

Induction of resistance to potato virus Y strain NTN in potato plants through RNAi.

Potato viruses cause enormous economic loss in agriculture production. Potatoes can be infected by a number of different viruses that affect negatively the harvest and the tuber quality. Direct and effective drugs against plant virus diseases are still not available and control is only applied as agricultural measures and pesticides against virus vectors. Potato virus Y (PVY) is transmitted by aphids in non-persistent manner and on that account using insecticides to prevent spread of the infection is useless. Breeding of resistant plant cultivars proved to be not always a solution of the problem because of the fast evolution of the virus strains and the constantly growing group of recombinants. In this study, we have proposed a new way of controlling the virus by blocking replication and transmission through the plant by RNAi-based vaccination of potato seedlings with specific to viral HC-Pro gene siRNAs. Thus, PVY replication is decreased without altering the valuable qualities of the sensitive to the virus potato cultivars like Agria.

Candidate gene approach for parasite resistance in sheep--variation in immune pathway genes and association with fecal egg count.

Sheep chromosome 3 (Oar3) has the largest number of QTLs reported to be significantly associated with resistance to gastro-intestinal nematodes. This study aimed to identify single nucleotide polymorphisms (SNPs) within candidate genes located in sheep chromosome 3 as well as genes involved in major immune pathways. A total of 41 SNPs were identified across 38 candidate genes in a panel of unrelated sheep and genotyped in 713 animals belonging to 22 breeds across Asia, Europe and South America. The variations and evolution of immune pathway genes were assessed in sheep populations across these macro-environmental regions that significantly differ in the diversity and load of pathogens. The mean minor allele frequency (MAF) did not vary between Asian and European sheep reflecting the absence of ascertainment bias. Phylogenetic analysis revealed two major clusters with most of South Asian, South East Asian and South West Asian breeds clustering together while European and South American sheep breeds clustered together distinctly. Analysis of molecular variance revealed strong phylogeographic structure at loci located in immune pathway genes, unlike microsatellite and genome wide SNP markers. To understand the influence of natural selection processes, SNP loci located in chromosome 3 were utilized to reconstruct haplotypes, the diversity of which showed significant deviations from selective neutrality. Reduced Median network of reconstructed haplotypes showed balancing selection in force at these loci. Preliminary association of SNP genotypes with phenotypes recorded 42 days post challenge revealed significant differences (P<0.05) in fecal egg count, body weight change and packed cell volume at two, four and six SNP loci respectively. In conclusion, the present study reports strong phylogeographic structure and balancing selection operating at SNP loci located within immune pathway genes. Further, SNP loci identified in the study were found to have potential for future large scale association studies in naturally exposed sheep populations.