Measuring and comparing constraints to improved biosecurity amongst GB farmers, veterinarians and the auxiliary industries.

Constraints to the introduction of enhanced biosecurity systems are rarely considered in sufficient detail when population medicine specialists initiate new control schemes. The main objective of our research was to investigate and compare the different attitudes constraining improvement in biosecurity for cattle and sheep farmers, practising veterinary surgeons and the auxiliary industries in Great Britain (GB). This study was carried out utilizing farmer focus groups, a questionnaire survey of veterinary practitioners and a telephone survey of auxiliary industry representatives. It appears that farmers and veterinarians have their own relatively clear definitions for biosecurity in relation to some major diseases threatening GB agriculture. Overall, farmers believe that other stakeholders, such as the government, should make a greater contribution towards biosecurity within GB. Conversely, veterinary practitioners saw their clients' ability or willingness to invest in biosecurity measures as a major constraint. Veterinary practitioners also felt that there was need for additional proof of efficacy and/or the potential economic benefits of proposed farm biosecurity practices better demonstrated. Auxiliary industries, in general, were not certain of their role in biosecurity although study participants highlighted zoonoses as part of the issue and offered that most of the constraints operated at farm level.

Salmonella, complement and mouse macrophages.

The structure of the polysaccharide chains that constitute the O antigen on the surface of Salmonella bacteria determines the rate of complement activation and C3b deposition on the bacteria. A fast-activating O antigen causes rapid C3-dependent opsonization of the bacteria injected intraperitoneally; as a consequence, the bacteria are taken up and killed by the resident peritoneal macrophages, and their virulence is low. A slow-activating O antigen protects the bacteria from opsonization in the peritoneal cavity, and is associated with higher virulence. However, if injected intravenously bacteria with either O-antigenic type are equally virulent; in the high complement concentration of the blood they become opsonized and taken up by macrophages in the liver and spleen, which are unable to kill them but instead provide a protected site for multiplication.

Expression and immunogenicity of an 18-residue epitope of HIV1 gp41 inserted in the flagellar protein of a Salmonella live vaccine.

A synthetic oligonucleotide specifying residues 735-752 of the product of the env gene of HIV1 IIIB was inserted by blunt-end ligation at restriction sites in the hypervariable, antigenically determinant region IV of two flagellin genes. Its integration, in frame and correct orientation, into gene fliC(d) in plasmid pLS408 allowed production of functional flagella when the plasmid was placed in a flagellin-negative aroA live-vaccine Salmonella dublin strain, SL5928. Bacteria thus made motile were immobilized and agglutinated by anti-(735-752 peptide) serum; expression was also shown by immunoelectron-microscopy and by Western blot of whole-cell lysates. Enzyme immunoassay (EIA) of sera of mice given three doses by intraperitoneal injection of the live-vaccine strain producing chimeric flagellin, or of concentrated flagella from it, showed production of antibody with affinity for the peptide, and in some sera, also for r-gp160. Pooled serum from mice given five i.p. doses of the live vaccine strain expressing the gp41 epitope at the surface of its flagellar filaments had higher titres of anti-peptide and anti-r-gp160 antibody and weak neutralizing activity on the IIIB isolate (90% neutralization at 1/100). The sera of nine mice given two doses of the live vaccine by the oral route had either no or only very low titres of antibody to flagellar antigen d; they were therefore not tested for anti-peptide activity.

Properties of food loads delivered to nestlings in the pied flycatcher: effects of clutch size manipulation, year, and sex.

Experimental manipulation of the number of altricial offspring is supposed to modify parental expenditure in birds. In addition to the observed increase in parental feeding rate, it is also possible that the choice of prey or the size of load may change with the changing demand for food. Sexual differences in the provisioning response are also expected, on the basis of earlier studies. We examined the effect of brood size manipulation on choice of prey brought to nestlings and load size in the pied flycatcher. The composition and size of loads differed between years, possibly depending on varying availability of different prey types. Males responded to brood size enlargement by gathering heavier loads, whereas females showed no response. The alteration of load size in males was not explained by a larger number of prey items or mean prey size, but was a combination of these components. It is likely that males also increased their work rate in response to increased food demand at the nest. The absence of response in females might be because they are unable to increase work rate any further, or because food delivery rate in females can not be optimized by changing load properties.

Incidence of clinical mastitis in dairy herds in England.

The annual incidence of clinical mastitis was measured in 144 Holstein/Friesian dairy herds in England (average size 132 cows) during 1994, 1995 and 1996 by means of carefully defined mastitis indices. The mean annual incidence of the disease over the three-year period was 43.4 quarter-cases per 100 cows, and the disease affected 25.9 per cent of the cows in the herds, with 1.6 quarter-cases per affected cow. In terms of cow-cases, the mean incidence was 39.9 cases per 100 cows in the herd and hence the ratio of quarter-cases to cow-cases was on average 1:1. The proportion of repeat quarter-cases was on average 19.4 per cent, and the recurrence rate was 18.3 per cent. The new infection rate was 28.3 per cent.

Protective immunity in mouse salmonellosis: comparison of smooth and rough live and killed vaccines.

Protective immunity against Salmonella infection was studied in a mouse model. To study specificity of protection we used smooth (O-4,5,12) and rough vaccines; live and killed vaccines of both types were compared. The protection was assessed by enumerating the number of bacteria in the livers, and by following survival of the mice after intravenous challenge with smooth O-4,5,12 bacteria. Passively transferred antibodies induced by the smooth vaccines had a small protective effect and those induced by the rough vaccines no protective effect in this model. Both live vaccines induced long-lasting protective immunity which was much stronger than that mediated by antibodies. Since the live rough vaccine induced protective immunity and contained no O antigen we conclude that the protective immunity induced by it was mainly cell-mediated and directed to other antigens than the O antigen, the target of protective antibodies. Both killed vaccines also induced protective immunity, but this was weaker than that induced by the corresponding live vaccine.

Plasmid-associated virulence of Salmonella enteritidis.

Plasmid-associated virulence of Salmonella enteritidis was studied using plasmid-cured and plasmid-reintroduced strains. The plasmidless strain was unable to grow in the liver of mice after intravenous inoculation. Reintroduction of the plasmid pEX106 from the original S. enteritidis fully restored its capacity to grow in the mice. The plasmid pEX102 of Salmonella typhimurium introduced into the plasmid-cured S. enteritidis had a similar effect. The smooth lipopolysaccharide character of the S. enteritidis strains was not affected by the presence or absence of the plasmid, and the same was true of their high resistance to complement in guinea-pig serum as such or with added antibody.

Application of ribotyping and IS200 fingerprinting to distinguish the five Salmonella serotype O6,7:c:1,5 groups: Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C, and Typhisuis.

Sixty-seven strains of the five described Salmonella serotypes having antigens 6,7:c:1,5, that is S. enterica serotype Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C, and Typhisuis, were examined for 16S rrn profile ribotype, presence of IS200 and phenotypic characters, including rate of change of flagellar-antigen phase and nutritional character. Choleraesuis sensu stricto and its Kunzendorf variant had related but distinct ribotypes. Therefore, ribotyping appears to be a suitable method for differentiating Choleraesuis non-Kunzendorf from Choleraesuis var. Kunzendorf. Some strains of Paratyphi C had 16S profiles that resembled that of Choleraesuis non-Kunzendorf, while others resembled that of Choleraesuis var. Kunzendorf. The Typhisuis profiles were like those of Choleraesuis non-Kunzendorf, while the Choleraesuis var. Decatur profiles were unlike those of any of the other four groups. Furthermore, IS200 fingerprinting discriminated between Choleraesuis var. Decatur and the other strains with antigenic formula O6,7:c:1,5, and comparison of IS200 patterns showed a high degree of genetic divergence within Choleraesuis var. Decatur. Our findings show that ribotyping and IS200 fingerprinting, combined with classical microbiological methods, distinguish the groups Choleraesuis non-Kunzendorf, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C and Typhisuis.

C-reactive protein serum levels in patients with ocular disease.

Hepatocyte derived C-reactive protein (CRP) is a sensitive indicator for inflammatory or infectious processes in a variety of tissues. As several other plasma proteins it is regarded as part of the acute phase response to a variety of tissue damage. CRP is commonly used in general medicine as a tool for the follow-up of especially bacterial infections. However, it has not been widely used in ophthalmology. In the present study CRP values in serum samples from 51 patients with various acute ocular diseases were determined semiquantitatively. High CRP levels were found most frequently in patients with either preseptal cellulitis (83.3%) or endophthalmitis (25.8%) whereas in the serum of patients with keratitis and uveitis, CRP exceeded 20 mg/l in only 18.7% of the cases. In a control group of 10 patients with retinal detachment the mean CRP level was 2.3 mg/l (SD +/- 0.98 mg/ml). The clinical significance and the prognostic value of CRP determinations during ocular diseases are discussed.

Immunogenicity of a fusion protein linking the beta subunit carboxyl terminal peptide (CTP) of human chorionic gonadotropin to the B subunit of Escherichia coli heat-labile enterotoxin (LTB).

Human chorionic gonadotropin (hCG) is currently under investigation as an antigenic target in both anti-cancer and anti-fertility vaccines. Formulations studied to date show promise in clinical trials for both applications yet are expensive to produce and require frequented administration in order to maintain an effective antibody titer. We have engineered a fusion protein consisting of Escherichia coli heat-labile enterotoxin subunit B (LTB) genetically linked at its C terminus via a nine amino acid linker to the 37 amino acid carboxyl terminal peptide (CTP) of the hCG beta chain. This LTB-CTP fusion protein is stably expressed in bacteria and forms pentamers of full-length protein subunits. Purified LTB-CTP protein hCG-specific antibodies in mice without additional adjuvants.