Molecular analysis of avian paramyxovirus serotype-1

Avian paramyxovirus serotype-1 (APMV-1) is capable of infecting a wide range of avian species leading to a broad range of clinical symptoms. Ease of transmission has allowed the virus to spread world-wide with varying degrees of virulence depending on the virus strain and host species. Classification systems have been designed to group isolates based on their genetic composition. The genetic composition of the fusion gene cleavage site plays an important role in virulence. Presence of multiple basic amino acids at the cleavage site allows enzymatic cleavage of the fusion protein enabling virulent viruses to spread systemically. Diagnostic tests, including virus isolation, real-time reverse-transcription PCR and sequencing, are used to characterize the virus and identify virulent strains. Genetic diversity within APMV-1 demonstrates the need for continual monitoring for changes that may arise requiring modifications to the molecular assays to maintain their usefulness for diagnostic testing

Evaluation of the BACTEC MGIT 960 system for recovery of Mycobacterium bovis

The BACTEC MGIT 960 system was evaluated to determine how it compares to the BACTEC 460 radiometric system for recovery of Mycobacterium bovis from tissue samples. Five hundred and six bovine lymph node samples were collected from 21 abattoirs in the United States and three in Mexico between November 2003 and September 2004. Processed samples were inoculated into a MGIT tube, BACTEC 460 vial, Middlebrook 7H10 and Middlebrook 7H11 solid media. The MGIT tubes were inserted into the MGIT 960 instrument for incubation and testing. The BACTEC 460 vials and MGIT tubes were incubated for six weeks (or until positive). Solid media tubes were incubated up to 8 weeks. Ziehl-Neelsen slides were prepared for each type of media to check for contaminants and confirm growth of acid-fast positive rods. Samples containing acid-fast rods were confirmed as members of the M. tuberculosis complex by a nucleic acid assay. Niacin and nitrate biochemical tests were used to distinguish M. bovis from M. tuberculosis isolates. The study shows the MGIT 960 system had a higher recovery rate of M. bovis than the BACTEC 460 and solid media systems. In addition the MGIT 960 system had the lowest mean time to detection. The BACTEC 460 and MGIT 960 systems had similar contamination rates. These results indicate the MGIT 960 system is better than the BACTEC 460 system for recovering M. bovis from tissue samples