الفهرس 
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Abstract
Paenibacillus larvae subsp. larvae, the causative pathogenic bacterium of virulent brood disease (American foulbrood, AFB). DNA extracted from P. l. larvae strain was subjected to PCR using specific primers of a partial sequence of 16S rRNA gene that closely related to the bacterium. Assayed bacterial strain produced a defined band of 700 bp in size. This test was done based on DNA – extraction of bacterial colonies and different larval stages(1-5 days, of age) from Carniolan (Apis mellifera carnica) honeybee and Italian (Apis mellifera ligustica), The results of PCR analysis showed that the (day1) of all honeybee races didn’t amplify the pathogen fragment (700bp) and all larval stages from (day2- day5) generated PCR fragment of 700bp. Also, this defined fragment was detected in larvae, pupae, adult worker and virgin queen resulted from the grafting Italian honeybee. On the other hand, the physicochemical structure of genomic DNA of pathogenic bacterium P. l. larvae and the two honeybee races before (-ve control) &after infection with the pathogen were identified and characterized qualitatively and quantitatively using molecular laser Raman (MLRS) and infra-red (FTIR) spectroscopies for the first time. The results of spectroscopic analysis clearly revealed that the pathogen was more abundant in Italian race from the early infection stage (day1) to (day5) of age. than Carniolan which showed more resistant to pathogen infection of the (day2). In Conclusion: 1- PCR and molecular laser Raman spectroscopy may serve as a qualitative biomarker to detect the presence or absence of pathogen infection of both races, compared to the (-ve) control. 2- MLRS confirmed that the maximum degree of infection was found to be in the early larval stages (day1- day2) of about 90% of both races, showing maximum sensitivity and minimum resistance 10%. 3- In Carniolan race after (day2), drastic DROP of the larval stages (day3-day5) in the degree of infection (63%) occurred leading to remarkable increase in larval resistance to pathogen of about (47%). 4- In contrast, the Italian race showed high degree of infection (91.2%) during all larvae stages, indicating that the Italian race is highly sensitive to the pathogen and less resistant, i.e.., low immunity against the pathogen. 5- Finally, MLRS proved to be a very sensitive and efficient tool for qualitative detection and quantitative evaluation of the degree or level of infection by the pathogen in the 5 stages (1-5day) of larval development of the two races.