Contamination rate of Avian Leukosis viruses among commercial Marek's Disease vaccines in Assiut, Egypt market using Reverse Transcriptase-Polymerase Chain Reaction

Avian leukosis viruses (ALVs) in poultry may induce a variety of deleterious effects including tumors, increased mortalities, growth retardation and decrease in egg size and production that led to considerable economic losses. The identification of avian leukosis viruses (ALVs) in imported Marek’s disease (MD) vaccines has raised concern about transmission of these retroviruses to vaccine recipients esp. poultry breeding stocks, so Egypt as one of importing countries requires freedom of infection with ALVs in such vaccines. Subgroup specific RT-PCR was undertaken on isolated RNA from 13 obtained commercial MD vaccines using six pairs of primers that correspond to envelope glycoprotein gene (gp85) which determines possible contamination with the six ALV subgroups: A, B, C, D, E, and J. The results indicated that RT-PCR assay for ALV-gp85 subgroup-E was positive for eight out of thirteen (61.5%) tested MD vaccines, while primers designed to detect subgroup A and J ALVs were positive for five out of thirteen (38.5%) and two out of thirteen (7.7%) respectively among examined vaccines. No ALVs was detected in 3/13 (23.07%) of commercially examined vaccines by using any of six primer pairs. Finally, the using of RT-PCR assay provides us a new, sensitive approach for identifying ALVs as a contaminant agent that will help greatly in applying this method for equipped labs as a quality control measure for testing delivered MD vaccines before its administration in poultry breeding stocks as well eradication programs through identifying infected birds. [Vet. World 2010; 3(1.000): 8-12

Mineralogical study and enhanced gravity separation of gold-bearing mineral, South Eastern Desert, Egypt

El-Hudi gold deposit, located in the South Eastern Desert of Egypt, represent large vein- type gold occurrence. The representative sample revealed the abundance of quartz as main constituent with minor amounts of mineral impurities. Gold was detectable (12 g/t) as determined using atomic absorption. The petrographic study revealed that the gold grains ranged from 10-40 μm. The grain boundaries of quartz are highly stained with iron minerals as hematite and limonite. Sericite mineral is common in discrete gold-bearing veins. Eroded pyrite was detected with high alteration leaving only cubic-shaped cavities behind. Different techniques for gravity separation were used to separate gold from the quartz mineral. After crushing and grinding of the sample, shaking table was used to upgrade the coarser fractions while Falcon concentrator was employed to upgrade the fine fraction. The best concentrate was obtained through grinding the whole sample to less than 0.2 mm, followed by cleaning steps. The gold content is increased from 12 to 145 g/t with total recovery of 78%

Serologic response of SPF chickens to live vaccines and other strains of Mycoplasma gallisepticum

False positive serologic reactions and difficulties in the diagnosis of Mycoplasma gallisepticum (MG) in chickens have increased lately as a result of infection by low virulent MG strains and the use of live MG vaccines in poultry. The objective of this study was to evaluate the serologic responses of SPF chickens exposed to the three commercially available live MG vaccines, and one low virulent MG strain (MG-70), contributing to the diagnosis and monitoring of MG infection in birds. Six groups of SPF chickens were used. The control group was not infected nor challenged; one group was infected with the low virulent strain MG-70 (MG-70); three groups were immunized and named after the MG vaccine used, i.e., MG-6/85, MG-ts11, and MG-F; and finally one group was infected with the virulent MG standard strain, MGR. Random Amplification of Polymorphic DNA (RAPDPCR) was used to compare the strains to each other, to the standard MG-A5969, and to MGR. All strains were found to be genetically distinguishable from each other. Birds in the control group showed negative results throughout the experiment and showed no cross-reaction with M. synoviae in any serologic test. ELISA tests at 21 days post first exposure (P1E) and seven days after the second exposure (P2E), evidenced that 25% of the MG70 birds were positive, whereas vaccine groups yielded higher positivity rate, i.e., 57%, 43% and 29% for MG-6/85, MG-ts11 and MG-F, respectively. Serum plate agglutination (SPA) evidenced the first positive results at 35 days P1E on birds in the MG-F group at the rate of 100%; followed by 40% of birds in the MG-70 group at 63 days P1E. Chickens in MG-ts11 and MG 6/85 groups had identical behavior and yielded 100% positive SPA at 77 days P1E. In regard to hemagglutination inhibition (HI), 14 % of the birds in MG-F and MG-ts11 reacted at 42 days P1E, while MG-70 and MG-6/85 groups yielded positive results only after challenge; MG-70 birds reacted at 56 days P1E at the rate of 17% against 63 days P1E for 100% of MG-6/85 birds. The time lag for positive serologic response was monitored on a weekly basis and was statistically different among groups (p<0.05) by Analysis of Variance (ANOVA). No clinical signs or gross lesions were seen in the control, vaccinated or MG-70 infected birds. Tracheitis and airsaculitis were observed in birds in the MG-R group. MG was isolated from all studied groups