Vaccination of 1-day-old chicks with fowlpox virus by the aerosol, drinking water, or cutaneous routes

Administration of 10(4) mean cell-culture infectious dose (CCID50) per ml of a plaque-purified derivative of a commercial fowlpox virus (FPV) vaccine to 1-day-old chicks by aerosol or drinking water gave inconsistent serological responses and little evidence of protective immunity. In contrast, cutaneous vaccination with the same preparation protected against challenge with virulent FPV at 4 weeks of age. Administration of the vaccine at a concentration of 10(6) CCID50 per ml by the drinking-water route was as effective as conventional cutaneous vaccination in terms of the serological response in an enzyme-linked immuno-sorbent assay and in terms of protection against challenge. Drinking-water vaccination at 2 days of age was no more effective than vaccination on day 1, and oral dosing with the vaccine was less effective than incorporation of the vaccine in the drinking water. It was concluded that 1-day-old chicks may be vaccinated against fowlpox by the drinking-water route if the vaccine contains a sufficiently high concentration of virus.     

Theory,preparation and ‘exhaustion’ on wool fibres of pesticide emulsions. I.—Theory of the stability of pesticide emulsions

Emulsifiable concentrates containing toxic agents are usually formulated with blends of anionic and non-ionic surfactants which determine the structure of the interfacial layer enveloping the suspended droplets. Electrostatic repulsion and London-van der Waals attraction decide their flocculation whereas other properties of the interfacial layer may also play an important part in their coalescence.     

Haemorrhagic nephritis and enteritis of geese: pathomorphological investigations and proposed pathogenesis

Haemorrhagic nephritis and enteritis of geese as a new disease was first described in Hungary in 1969. The authors identified the causative agent of the outbreaks occurring in 1969 as a polyomavirus by PCR in 2001. In order to study the pathogenesis of the virus, one-day-old goslings were infected with tissue homogenate that tested positive for polyomavirus by PCR. Morphological, light and transmission electron microscopic (TEM) examinations have revealed that goose haemorrhagic polyomavirus replicates in the endothelial cells of the blood vessels and capillaries of diseased birds. Infection causes damage and necrosis of the endothelial cells. The virus was not observed in the parenchymal cells. Oedema and haemorrhages found throughout the body may be due to the dysfunction or functional deficiency of endothelial cells damaged by the virus.     

A possible relationship between viral infection and chromosome damage in breeding boars

A cytogenetic analysis of peripheral blood lymphocytes was carried out on breeding boars (n = 5) on a farm where viral infections (porcine parvovirosis) had occurred. Several different types of chromosomal aberrations were observed including chromatid breaks (23.60 +/- 2.88%), exchanges (9.60 +/- 8.99%), and fragments (4.26 +/- 3.31%). In addition, 2.94 +/- 1.74% of cells in metaphase showed pulverization. Cells with multiple aberrations were seen in two of five boars. The chromosomal damage in the boars may have been induced by a genotoxic agent such as a viral infection, and may also be related to the reproductive impairment of the pigs.     

Genes responsible for anaerobic fumarate and arginine metabolism are involved in growth suppression in Salmonella enterica serovar Typhimurium in vitro, without influencing colonisation inhibition in the chicken in vivo

From a collection of over 2800 Salmonella enterica subspecies Enterica serotype Typhimurium F98 Tn5-TC1 insertion mutants 14 were identified as expressing growth-non-suppressive phenotype under strict anaerobic conditions. Sequence analysis of regions flanking the Tn insertions revealed that most of the selected mutants were defective in genes contributing to the anaerobic fumarate uptake and generation (insertions in dcuA, dcuB and aspA), or to the anaerobic L-arginine utilisation pathway (insertions in STM4467 encoding a putative arginine deiminase, and in between speF encoding ornithine decarboxylase and kdpE coding a response regulator protein). Mutants defective in flagellum synthesis (flhA) were also identified. In contrast to the in vitro results, all the mutants colonised 1-day-old chicks efficiently and suppressed the super-infection of chicks by the parent strain. This clearly indicates that neither of the metabolic pathways mentioned above nor motility play essential roles in lower intestinal tract colonisation.     

Depletion of gentamicin and its major components from various tissues of turkeys

OBJECTIVE: To determine tissue depletion profiles for gentamicin and its 3 major components (C1, C1a, and C2) in turkeys. ANIMALS: Twenty 10-week-old male turkeys. PROCEDURE: birds were maintained as untreated controls. The remaining birds were treated with gentamicin sulfate at a dosage of 2 mg/kg, IM, once daily for 5 days. Treated birds were euthanatized 45, 60, 75, and 90 days (4 birds at each sample time) after the last dose of gentamicin was administered, and samples of muscle, liver, kidney, and skin and fat were collected. Control birds were euthanatized on day 45. Concentrations of the 3 major components of gentamicin were measured by means of reversed-phase high-performance liquid chromatography. RESULTS: Total gentamicin concentration (ie, sum of the concentrations of the 3 major components) was < 100 microg/kg for all muscle and skin and fat samples by day 45 and all liver samples by day 75. At all sample times, concentration of the gentamicin C1 component was higher than concentrations of the C1a and C2 components in all tissues. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that tissue depletion profiles of the 3 major components of gentamicin differ from each other. Withdrawal time, therefore, may depend on the ratio of the components in the pharmaceutical preparation used.     

Use of a polymerase chain reaction assay to detect bovine leukosis virus in dairy cattle

OBJECTIVE: To evaluate the use of a polymerase chain reaction (PCR) assay in detecting bovine leukosis virus (BLV) in adult dairy cows. DESIGN: Prospective study. ANIMALS: 223 adult dairy cows. PROCEDURE: Cows were tested for BLV status by use of an ELISA and a PCR assay. Sensitivity, specificity, predictive values of positive and negative tests, and the percentage of cows correctly classified by PCR assay were calculated. Ninety-five percent confidence intervals were calculated for sensitivity and specificity. RESULTS: Sensitivity and specificity were 0.672 and 1.00, respectively. Prevalence of BLV in this herd was 0.807. Predictive value of a positive test was 1.00, and predictive value of a negative test was 0.421. The percentage of cows correctly classified by PCR assay was 73.5%. CONCLUSIONS AND CLINICAL RELEVANCE: A positive PCR assay result provided definitive evidence that a cow was infected with BLV. Sensitivity and negative predictive value for PCR assay were low. Consequently, PCR assay alone is unreliable for routine detection of BLV in herds with high prevalence of the disease.