RESUMO
BACKGROUND AND AIM: Avian colibacillosis, which is caused by avian pathogenic Escherichia coli (APEC), is a major bacterial disease that affects birds of all ages worldwide, causing significant economic losses. APEC manifests in several clinical forms, including cellulitis, and its high pathogenicity is attributed to harboring numerous virulence-associated genes (VGs). This study evaluated the pathogenicity of the cellulitis-derived E. coli (O78) strain through molecular identification of genes coding for seven virulence factors and by conducting an in vivo assessment of capability for cellulitis induction in broiler chickens. MATERIALS AND METHODS: This study was performed using a previously isolated and identified cellulitis-derived E. coli (O78), which was screened for seven VGs using molecular detection and identification through polymerase chain reaction followed by nucleotide sequencing and phylogenetic analysis. Experimental infection by subcutaneous (SC) inoculation in broilers and its pathogenicity was confirmed in vivo by cellulitis induction. The impact of cellulitis on broiler performance was assessed. RESULTS: Molecular genotyping proved that the isolate harbored five virulence genes (iroN, iutA, tsh, iss, and papC) and was negative for stx1 and hly genes. The amplified products for iroN, iss, and iutA were subjected to sequencing and phylogenetic analysis, and the results indicate the highest similarity and matching with E. coli submitted to the National Center for Biotechnology Information GenBank. SC inoculation of bacteria in broiler chickens resulted in cellulitis, as indicated by thick red edematous skin with yellowish-white material in the SC tissue at the inoculation site, and the abdominal muscle showed redness and increased vacuolization. Histopathological examination revealed moderate-to-severe caseous inflammatory reaction with a marked accumulation of heterophils and mononuclear cells in the SC fatty tissue. The average feed intake, body weight gain (BWG), and feed conversion ratio (FCR) were lower in infected chickens in comparison with those of the control non-infected chickens. CONCLUSION: This study proves that molecular techniques are accurate for pathogenicity determination in virulent bacteria, with the advantages of being rapid, time-saving, and economical. Cellulitis is associated with economic losses that are represented by a lower BWG and FCR.
RESUMO
BACKGROUND AND AIM: Recently, it has been recorded unexpected percentage of cutaneous squamous cell carcinoma (cSCC) in sheep. Despite the improvement in surgical treatment, the outcome of animals remains limited by metastatic relapse. Although antibodies for cancer treatment have been practiced for many decades, the use of this methodology in animals is deficient. This study aimed to establish cSCC therapy by tumor cell protein antibody (Ab1) or secondary antibody (Ab2) raised by two series of immunization in the same strain of rabbits. MATERIALS AND METHODS: A total of 19 Ossimi sheep were used (14 sheep suffered from cSCC and 5 were apparently healthy). Each animal from control healthy group (n=5) and control cSCC (n=4) group was treated with a course of eight injections of normal globulins. Animals in the third (n=5) and the last (n=5) groups received a course of eight injections of Ab1and Ab2, respectively. Each tumor was measured before and after treatment. The eight injections were applied at 1st, 3rd, 5th, 7th, and 9th week and the remaining three injections were at 1 week interval. Tissue specimens and blood samples were taken for histological and immunological studies. RESULTS: The obtained results revealed that injection of Ab1 might prevent the bad prognostic picture of polymorph infiltration without any criteria of regression % of tumor. Treatment with Ab2 showed regression of tumor size ranged between minimum of 8.99% and maximum of 78.12%, however, the measurements in most cases reached the maximum regression after the past two injections. In additions, infiltration of lymphocytes to tumor site, normalization of leukocytes picture and also increase of antibody titer were observed. CONCLUSION: This profile might confirm that Ab2 could act as an antigen and encourage us to use it as a tumor vaccine. Extensive studies are needed to isolate the idiotypic portion of Ab1 for raising Ab2 as an anti-idiotypic antibody to be used as tumor vaccine. The question of how lymphocyte traffic to the tumor site as a result of Ab2 injection needs further investigation.
