A survey of Campylobacter jejuni in broilers from assignment to slaughter using DNA-DNA hybridization

A survey of Campylobacter jejuni in the cecal contents of broilers raised on a farm was carried out by the DNA-DNA hybridization method from the day of assignment to slaughter at about 1-week intervals. C. jejuni was detected in chickens as early as 1 week of age, and was widely detected at each week of age throughout the growing period. In addition, of 20 chickens tested just after assignment, 7 (35%) were C. jejuni positive. It is suggested that newly introduced chickens may have already been contaminated with C. jejuni. The hybridization method was able to detect C. jejuni in the chickens from the day of assignment to 3 weeks of age, but C. jejuni was never detected in the same chickens by the enriched culture method. Therefore, it is suggested that the hybridization method is more sensitive than the enriched culture method.

Application of a DNA-DNA hybridization method for detection of Campylobacter jejuni in chicken feces

A direct colony hybridization method was used for the detection of Campylobacter jejuni in chicken feces. The biotin-labeled DNA prepared from the whole genome DNA of C. jejuni subsp. jejuni ATCC 33560 reacted well with homologous DNA and slightly with C. coli DNA. The method with the probe was found to be sensitive enough to detect a small number (10(2) CFU/g) of C. jejuni in chicken feces which contained a large number of background flora. It was suggested that this simple and sensitive method was useful for a wide survey of C. jejuni.

Characterization of the genes encoding two of the major capsid proteins of epizootic haemorrhagic disease virus indicates a close genetic relationship to bluetongue virus

The sequences of the genes of two of the major capsid proteins of epizootic haemorrhagic disease virus serotype 1 (EHDV-1, Orbivirus genus, Reoviridae) have been determined by analyses of cDNA clones representing the L2 and S7 RNA segments. The EHDV-1 S7 RNA segment, which encodes the VP7 core protein, is 1162 nucleotides in length and has the capacity to encode 349 amino acids (M(r) 38,243). The EHDV-1 L2 RNA segment, which encodes the outer capsid VP2 protein (M(r) 113,249) is 2968 nucleotides in length and has an open reading frame of 971 codons. The potential secondary structure of the EHDV-1 S7 mRNA species, in particular that of the terminal regions, is comparable to those of the corresponding segments of bluetongue virus (BTV) and African horse sickness virus (AHSV); the EHDV-1 L2 mRNA species has a secondary structure similar to that of the L2 mRNA of BTV. The EHDV-1 VP2 and VP7 proteins, as well as those of the other two major structural proteins of EHDV published previously (the inner core VP3 protein and the second outer capsid, VP5), are closely related to the corresponding proteins of BTV. The EHDV and BTV VP7 sequences are more distantly related to the sequence of the AHSV VP7 protein published recently.

Expression of the major core antigen VP7 of African horsesickness virus by a recombinant baculovirus and its use as a group-specific diagnostic reagent

The major core protein, VP7, of African horsesickness virus serotype 4 (AHSV-4), the aetiological agent of a recent outbreak of the disease in southern Europe, was expressed in insect cells infected with a recombinant baculovirus containing a cloned copy of the relevant AHSV gene (S7). Analyses of its biochemical and antigenic properties confirmed the authenticity of the protein expressed. The high-level expression of VP7 under the control of the strong polyhedrin promoter of Autographa californica nuclear polyhedrosis virus induced disc-shaped crystals in infected insect cells. This enabled us to purify the protein by a one-step ultracentrifugation procedure and to utilize it for the detection of antibodies raised in horses to various serotypes of AHSV. A serological relationship between AHSV and two other orbiviruses, bluetongue virus and epizootic haemorrhagic disease virus, was also demonstrated.