Evaluation of a Killed Vaccine Against Porcine Pleuropneumonia Due to Haemophilus pleuropneumoniae

A bacterin containing serotypes 1 and 5 of Haemophilus pleuropneumoniae was developed for the prevention and the control of porcine pleuropneumonia. It was injected intramuscularly into three groups of ten piglets, the first group with one dose, the second one with two doses and the third one with three doses at two-week intervals. Another group of ten piglets did not receive the vaccine. All the piglets were then challenged by an aerosol of mixed suspensions of H. pleuropneumoniae serotypes 1 and 5. Two and three injections of vaccine completely prevented mortality, whereas half of the control piglets and of those receiving only one dose of vaccine died. All surviving piglets, both control and vaccinated, had severe signs of respiratory disease for at least 36 hours after exposure to challenge. Moreover, vaccination did not induce the production of antibodies at high titers. Local reactions were not noted after vaccination and at postmortem; ten weeks after the challenge, there were no signs of abscess formation or induration.     

Escherichia coli strains isolated from diarrheic piglets in the Province of Quebec.

During 1972 to 1974, 112 Escherichia coli strains isolated from diarrheic piglets were recieved from different parts of the Province of Quebec, Canada. Fifty-six strains elicited a positive gut loop response in three week old piglets and were then considered as Moon's class 1 enteropathogens, while four of the 56 remaining strains reacted only in ten day old piglets and were classified as class 2 enteropathogens. Forty-eight strains produced both a heat-labile and a heat-stable enterotoxin, while 12 isolates which included the four class 2 enteropathogens produced only a heat-stable enterotoxin. Fifty-one enterotoxigenic strains could be serogrouped using OK antisera against E. coli strains commonly associated with colibacillosis in piglets. The most common serogroups encountered were O157: K "V17"; 88a,c, O149:K91; 88a.c. O157:K"V1c, O149:K91; 88a.c, O157:K"V17"; 88 a,c or a,b and O45:K"E5"; 88a,c. No significant difference was observed in the fermentation patterns, antibiotic susceptibility, colicin production, production of a filterable hemolysin and transferable tetracycline resistance between the enterotoxigenic and the nonenterotoxigenic strains.     

Electrocorticogram disturbances detected in rats exposed from early stages of life to residual doses of lindane

Functional brain alterations induced by lindane were examined in Rat chronically exposed to low doses of lindane (1 and 2 μg L⁻¹ in drinking water) from conception. Histological and electrophysiological investigations were conducted at 14 weeks of age. Lindane did not induce histological changes. It did not significantly modify the sleep-wakefulness cycle and EEG did not show major alterations. The spectral EEG analysis, by recording cortical variations in both energy spectrum and energy levels of different frequency bands, showed an increase in the 11-15 Hz activity in both groups exposed to lindane. This activity was characterised by spindles well-depicted during slow wave sleep or associated with fast activity during wakefulness and theta activity in paradoxical sleep. These data suggest that chronic exposure to lindane doses as low as 1 μg L⁻¹ in drinking water could lead to central electrophysiological effects possibly involving GABA-benzodiazepine mechanisms.     

Further Contributions to the Development of a Differential Set of Pea Cultivars (Pisum sativum) to Investigate the Virulence of Isolates of Aphanomyces euteiches

Common root rot (Aphanomyces euteiches Drechs.) has become a very destructive disease in the French pea crops since 1993. For an accurate investigation of the virulence variability among French A. euteiches populations and between French and foreign populations, a new set of differential pea genotypes was developed. Thirty-three American and European pea lines, displaying different levels of resistance, were screened in a growth chamber against two French isolates. Symptoms (disease severity from 0 to 5, evaluating symptom surface on roots and epicotyl) and percentage of top fresh weight (inoculated/uninoculated top fresh weight ratio) were measured. From this screening 12 relatively resistant lines, from various genetic backgrounds, were identified along with a highly susceptible control. This set of 13 genotypes was inoculated under controlled conditions with 14 isolates from France, Sweden, USA, Canada and New Zealand, to investigate genotype–isolate interactions. Root symptoms were rated (disease severity), and a susceptibility/resistance threshold was established at disease severity = 1. Significant quantitative interactions were observed, and five 'resistance patterns' were identified, leading to a set of six pea genotypes: Baccara (susceptible), Capella, MN313, 902131, 552 and PI180693. Fields trials of this set in 1999 and 2000 gave the same resistance rankings than in growth chamber conditions. This set will allow more accurate assessments of the variability in virulence/aggressiveness of A. euteiches isolates from France and foreign countries, and further investigations of the epidemiological and genetic basis of pea–A. euteiches interactions.     

Effects of surgical implantation of temperature dataloggers on reproduction of captive striped skunks (Mephitis mephitis).

A total of 20 (14 females, six males) captive striped skunks (Mephitis mephitis) with miniature temperature dataloggers implanted free in the abdominal cavity were examined for reproductive performance and pathology because of implants. Eleven of 12 female skunks reproduced successfully 45.9+/-3.7 days after surgery to remove implanted dataloggers. The pregnancy rate of 91.7% (11/12) was much higher than other captive studies and was comparable with that of wild skunks. Eight striped skunks (six males, two females) that were euthanatized and necropsied after having implants in the abdominal cavity for 5 mo showed no apparent pathology associated with the implant. Implantation of the intraperitoneal devices did not lead to complications in abdominal tissues. Neither implant nor surgery affected reproduction. We conclude that implanted dataloggers can safely be used in physiologic studies of striped skunks or possibly other small carnivores in captive or field studies.