Unique hemagglutination activity of an isolate of Newcastle disease virus.

The MET95 strain of a lentogenic Newcastle disease virus (NDV) isolated from a broiler in Japan, showed unique hemagglutination (HA) activity. The MET95 strain failed to show HA when examined by rapid glass plate method although they showed HA titer of 1:1,024 by micro-plate method. This unique HA was also observed after the MET95 strain was passaged ten times in chickens. The failure of HA by rapid glass plate method was not shown in any other NDVs examined.

Serological monitoring on layer farms with specific pathogen-free chickens.

To monitor the existence of avian pathogens in laying chicken flocks, specific pathogen-free (SPF) chickens were introduced into two layer farms and reared with laying hens for 12 months. SPF chickens were bled several times after their introduction and examined for their sero-conversion to avian pathogens. As a result, antibodies to eight or ten kinds of pathogens were detected in SPF chickens on each farm. Antibodies to infectious bronchitis virus (IBV), avian nephritis virus, Mycoplasma gallisepticum and M. synoviae were detected early within the first month. Antibody titer to IBV suggested that the laying chickens were infected with IBV repeatedly during the experiment on both farms. However, antibodies to infectious bursal disease virus and 6 pathogens were not detected.

Molecular characterization of the mde operon involved in L-methionine catabolism of Pseudomonas putida.

A 15-kb region of Pseudomonas putida chromosomal DNA containing the mde operon and an upstream regulatory gene (mdeR) has been cloned and sequenced. The mde operon contains two structural genes involved in L-methionine degradative metabolism: the already-identified mdeA, which encodes L-methionine gamma-lyase (H. Inoue, K. Inagaki, M. Sugimoto, N. Esaki, K. Soda, and H. Tanaka. J. Biochem. (Tokyo) 117:1120-1125, 1995), and mdeB, which encodes a homologous protein to the homodimeric-type E1 component of pyruvate dehydrogenase complex. A rho-independent terminator was present just downstream of mdeB, and open reading frames corresponding to other components of alpha-keto acid dehydrogenase complex were not found. When MdeB was overproduced in Escherichia coli, the cell extract showed the E1 activity with high specificity for alpha-ketobutyrate rather than pyruvate. These results suggest that MdeB plays an important role in the metabolism of alpha-ketobutyrate produced by MdeA from L-methionine. Accordingly, mdeB encodes a novel E1 component, alpha-ketobutyrate dehydrogenase E1 component, of an unknown alpha-keto acid dehydrogenase complex in P. putida. In addition, we found that the mdeR gene was located on the opposite strand and began at 127 bp from the translational start site of mdeA. The mdeR gene product has been identified as a member of the leucine-responsive regulatory protein (Lrp) family and revealed to act as an essential positive regulator allowing the expression of the mdeAB operon.