Inhibitory effects of several essential oils towards salmonella typhimurium, salmonella paratyphi A and salmonella paratyphi B

Plant essential oils are natural products extracted from plants and because of their antimicrobial properties can be used as natural additives in foods. They are also useful for decontamination of food-borne pathogens and can be a safe additive in foods. The antimicrobial activities of essential oils belonging to Saturiea hortensis, Thymus vulgaris, Mentha polegium, Cuminum cyminum, Lavandula officinalis and Mentha viridis L. [spearmint] were investigated at different concentrations [0.1, 0.3, 0.5, 1, 2, 5 and 10%v/v] against Salmonella typhimurium, Salmonella paratyphi A and Salmonella paratyphi B by using the agar well diffusion method. Essential oils showed inhibitory effect on Salmonella spp. in the agar well diffusion assay. In addition, the capability of essential oils for decontamination of minced row beef, ground beef, minced raw chicken and minced raw fish inoculated with Salmonella spp. at 0.1 and 0.5%v/v were assessed. Reduction of the Salmonella spp. population was observed following the inoculation of the cultures with 0.1 and 0.5%v/v essential oils

Detection of pestivirus contamination in cellcultures by nested-PCR

In this study a nested-PCR assay was optimized for detection of two BVDVbiotype of NADL strain. Apart of 5' non-coding region of virus, 249 bp in size, was amplified in RT-PCR. PCR product was cloned in a pTZ57R/T vector and sequencing results confirmed the specificity of the test. Internal primers were designed and a 155 bp DNAfragment was amplified in nested-PCR. The 4 sensitivity of RT-PCR and nested-PCR for detection of virus in cell culture were found to be 10 2 TCID50 and 10 TCID50, respectively. Seven cell cultures were tested for BVDVcontamination using ELISA, RT-PCR and nested-PCR. Results indicate that sensitivity of molecular tests for detection of virus in cell culture samples is higher than ELISA

Polymerase chain reaction for the detection and differentiation of Marek's disease virus strains MDV-1 and HVT

Marek's disease [MD] is a lymphoproliferative disease of chickens characterized by lymphocytic infiltration of various organs. The present study was an attempt to use polymerase chain reaction [PCR] to optimize a rapid and reliable assay for detection of MDV genome. Detection of serotype I of MDV [MDV-l] was confirmed by presence of a 200 bp DNA fragment as a PCR product. Differentiation of MDV- I and herpesvirus of turkeys [HVT] was also conducted using specific primers from the glycoprotein A [gA] gene and a 388 bp DNA fragment was amplified from HVT genome. The specificity of the test was confirmed by sequencing of PCR products. Results indicate that MDV-l can be diagnosed in clinical samples and inoculated cell cultures which is used for virus isolation. In addition, differentiation between MDV- I and HVT viruses was confirmed based on the size of PCR products. The test proved to be rapid and reliable and be performed as a robust diagnostic test in veterinary diagnostic laboratories