Molecular characterisation of rabies virus detected in livestock animals in the southern part of Egypt during 2018 and 2019.

Brain samples were collected from 33 animals of different species, including buffalo, cattle, dog, donkey, fox and wolf, that had been suspected to be infected by rabies virus (RABV) in different geographical regions of Aswan and Luxor governorates in Egypt. The samples were submitted for histopathological examination and the presence of the nucleic acid and antigens of RABV was tested by RT-PCR and indirect fluorescent antibody technique (IFAT), respectively. Sixteen samples were found positive by all the three examinations. Three samples were selected for further study from animals in which the highest virus loads were detected. The partial sequence of the RABV N gene was determined and analysed from the samples of a buffalo, a cow and a donkey. The viruses in the samples were found to share 95-98% and 95-97% nucleotide and amino acid sequence identities, respectively. In comparison to reference sequences, a few amino acid substitutions occurred in the N protein antigenic sites I and IV in the immunodominant epitopes of the viruses detected in the cow and the donkey but not in the one from the buffalo. The phylogenetic analysis revealed that the RABVs sequenced from the samples belonged to genotype 1, Africa-4 clade, and formed two distinct sub-clades within the Egyptian clade. These findings indicate the circulation of RABV among livestock animals in the southern part of Egypt and raise public health concerns. The amino acid changes detected in this work may contribute to the antigenic diversification of RABVs.

Molecular analysis of Pasteurella multocida strains isolated from fowl cholera infection in backyard chickens

Objective: To characterize Pasteurella isolated from backyard chickens using whole cell protein lysate profiles and random amplified polymorphic DNA (RAPD) techniques to show their genetic relationship because Pasteurella multocida (P. multocida) is an important cause of fatal infections in backyard chickens. Methods:Twenty one P. multocida isolates were recovered previously from clinical cases of fowl cholera belonging to individual owners and phenotypically analyzed using biochemical tests and serotyping were used for the genetic characterization. Results:Phylogenetic study based on both methods revealed that the recovered population of P. multocida isolated from backyard chickens differs markedly, constituting a well-separated cluster and appearance of 3 distinguishing lineages with greater discrimination shown by RAPD-PCR that resulted in two suclusters in cluster A and three subclusters in cluster B and were related greatly with capsular serogroups for the examined strains. The whole cell protein revealed the presence of dominant protein bands at approximately 41 and 61 kDa in all of the examined isolates that may be a virulent proteins share in the increasing of its pathogenicity. Clear distinctive bands ranged from 123 to 1 554 bp. Conclusions: Based on the previous findings, there are three spreading clusters that may indicate the association of a small number of P. multocida variants with the majority of cases suggesting that certain clones of P. multocida are able to colonize the examined backyard chickens. Also, the ease and rapidity of RAPD-PCR support the use of this technique as alternative to the more labour-intensive SDS-PAGE system for strain differentiation and epidemiological studies of avian P. multocida. Further application of RAPD technology to the examination of avian cholera outbreaks in commercially available flocks may facilitate more effective management of this disease by providing the potential to investigate correlations of P. multocida genotypes, to identify affiliations between bird types and bacterial genotypes, and to elucidate the role of specific bird species in disease transmission.