Genetic and morphological characterization of a new genotype of nervous necrosis virus circulating among Nile tilapia in the south of Egypt

Nervous necrosis virus (NNV) is the causative agent of viral nervous necrosis in freshwater and marine fishes. In this study, NNV circulating among wild and farmed Nile tilapia (Oreochromis niloticus) was genetically and morphologically characterized using reverse transcription polymerase chain reaction (RT-PCR), sequencing analysis, and transmission electron microscopy (TEM). Brain, eye, and other organ (spleen, kidney, heart, and liver) specimens were collected from 87 wild (66) and farmed (21) Nile tilapia fish during their adult or juvenile stage at different localities in Qena and Sohag governorates in southern Egypt. Among them, 57/87 fish showed suspected NNV clinical signs, and 30/87 were healthy. The results revealed that NNV was detected in 66 out of 87 fish (58.62% in the wild and 17.24% in farmed Nile tilapia by RT-PCR), and the prevalence was higher among diseased (55.17%) than in healthy (20.69%) fish. NNV was detected in the brain, eye, and other organs. Using TEM, virion size variations based on the infected organs were observed. Nucleotide sequence similarity indicated that NNVs had a divergence of 75% from other fish nodaviruses sequenced in Egypt and worldwide. Phylogenetic analysis distinguished them from other NNV genotypes, revealing the emergence of a new NNV genotype in southern Egypt. In conclusion, NNV is circulating among diseased and healthy Nile tilapia, and a new NNV genotype has emerged in southern Egypt. (AU)

Genetic and morphological characterization of a new genotype of nervous necrosis virus circulating among Nile tilapia in the south of Egypt.

Nervous necrosis virus (NNV) is the causative agent of viral nervous necrosis in freshwater and marine fishes. In this study, NNV circulating among wild and farmed Nile tilapia (Oreochromis niloticus) was genetically and morphologically characterized using reverse transcription polymerase chain reaction (RT-PCR), sequencing analysis, and transmission electron microscopy (TEM). Brain, eye, and other organ (spleen, kidney, heart, and liver) specimens were collected from 87 wild (66) and farmed (21) Nile tilapia fish during their adult or juvenile stage at different localities in Qena and Sohag governorates in southern Egypt. Among them, 57/87 fish showed suspected NNV clinical signs, and 30/87 were healthy. The results revealed that NNV was detected in 66 out of 87 fish (58.62% in the wild and 17.24% in farmed Nile tilapia by RT-PCR), and the prevalence was higher among diseased (55.17%) than in healthy (20.69%) fish. NNV was detected in the brain, eye, and other organs. Using TEM, virion size variations based on the infected organs were observed. Nucleotide sequence similarity indicated that NNVs had a divergence of 75% from other fish nodaviruses sequenced in Egypt and worldwide. Phylogenetic analysis distinguished them from other NNV genotypes, revealing the emergence of a new NNV genotype in southern Egypt. In conclusion, NNV is circulating among diseased and healthy Nile tilapia, and a new NNV genotype has emerged in southern Egypt.

Detection of Stachybotrys chartarum isolates from faba beans dust during threshing.

Stachybotrys (S.) chartarum had been related to dangerous health problems in animals and humans that take place when exposure to S. chartarum toxins. S. chartarum had been isolated from various substrates, ranging from inappropriately stored feed and culinary herbs to damp buildings. To evaluate the pathogenic potential of isolates, it is essential to identify them with different methods. The occurrence and genetic diversity of S. chartarum isolates from faba beans dust during threshing in Upper Egypt were investigated. Low counts of Stachybotrys were found (six isolates) and identified morphologically by single-spore isolation and molecularly by the amplification of the specific internal transcribed spacer (ITS) region and glyceraldehydes-3-phosphate dehydrogenase (gpd). The genetic diversity of the collected isolates was studied by specific genes random primer polymerase chain reaction (SGRP-PCR). The phylogenetic analysis of S. chartarum showed that the specific primers IT51 and StacR3 used by commercial laboratories for detecting S. chartarum were not able to differentiate species of S. chartarum from S. chlorohalonata and unweighted pair group method of arithmetic averages (UPGMA) cluster analysis of SGRP fragments confirmed this result. The six isolates of S. chartarum were analyzed for the presence of trichodiene synthase (Tri5) gene, which needed in the early stage of the trichothecene synthesis path. All the tested isolates were positive for the Tri5 gene. Further study on the taxonomic status of the epithet S. chartarum is necessary and presence of sub species to S. chartarum might be acceptable depending on the variations of morphological characteristics which were confirmed by molecular techniques.

Morphological, molecular characterization, plant pathogenicity and biocontrol of Cladosporium complex groups associated with faba beans.

Vicia faba (faba bean) is one of the most significant leguminous crops. The faba bean is specialized by maximum nutritional value, in energy and protein content, which leads it to be suitable for food and feed production. Diseases caused with fungi are amongst the biotic factors responsible for decreasing in faba bean yields. In this work, Cladosporium isolates were recorded in cultivated faba bean leaves and pods collected from markets in Qena, Upper Egypt; morphological features and molecular characterization based on actin gene were performed. The ability of the pathogens to cause disease in faba bean seedlings and the biocontrol method to avoid the pathogenic effect of Cladosporium were determined. Results showed that Cladosporium is the main genera isolated from faba beans, and the morphological criteria showed presence of three species complex groups of Cladosporium (C. cladosporioides, C. herbarum and C. sphaerospermum) and the confirmation with molecular characterization revealed the existence of four species in the three groups. All the 26 tested strains of Cladosporium were able to cause leaf lesions on Vicia faba seedlings with different levels. Chaetomium globosum is a biocontrol agent could inhibit the growth of the majority strains of Cladosporium.

Molecular Identification of Penicillium sp. Isolated from Citrus Fruits.

Penicillium is one of the most important postharvest pathogens of citrus fruits worldwide. It induces blue or green mold disease, a decay that can lead to significant economic losses during storage. Based on internal transcribed spacer (ITS) sequences, seven Penicillium species and one closely related Talaromyces variabilis were identified from 30 rotten samples of citrus fruits marketed in Qena. Penicillium expansum was the most common species, recovered from 16.7% of the samples, followed by P. chrysogenum (10%) and P. polonicum (10%). Sixteen isolates were tested through inoculation on healthy citrus fruits; the data exhibited that 68.7% of isolates were highly virulent. A "Specific Gene Random Primer Polymerase Chain Reaction (SGRP-PCR)" marker technique indicated that the genetic similarity among P. expasum ranged from 49.4 to 85.7%, and a relatively correlation was found between SGRP band profile and species origin. Patulin was detected in 40% of P. expansum isolates. This study provided a useful molecular approach to identify different Penicillium species by sequencing ITS region, focus on the pathogenicity, compare between P. expansum isolates and their ability in patulin production.