Number Of Infected Animals Research Articles

Serpulina hyodysenteriae challenge of fattening pigs vaccinated with an adjuvanted bivalent bacterin against swine dysentery

An experimental fattening period was performed with 36 pigs in order to evaluate the safety and efficacy of a bivalent adjuvanted Serpulina hyodysenteriae bacterin. The pigs originated from three different farms and were split into six groups. Eighteen pigs were vaccinated twice, two weeks apart and the rest served as controls. One unvaccinated pig in each group was inoculated intragastrically with 4×10 8 active S. hyodysenteriae spirochaetes, B 78 strain. Weight evolution, clinical symptoms, shedding of S. hyodysenteriae and serum antibody titres were monitored for 12 weeks in all pigs. The severity of clinical symptoms and shedding of spirochaetes in faeces were significantly reduced in vaccinated pigs as compared to controls. Statistically significant differences in weight gain between vaccinates and controls were detected coinciding with the maximum shedding of S. hyodysenteriae in faeces. All vaccinated pigs seroconverted, as measured by indirect ELISA, and had a good anamnestic response after the second vaccine dose. The bacterin proved to be useful for both the reduction of clinical symptoms and the number of infected animals in a fattening unit. Adverse post-vaccinal reactions were not observed in any pig.

Effect of Treatment with Exogenous Interferon, Polyriboinosinic-Polyribocytidylic Acid, or Polyriboinosinic-Polyribocytidylic Acid-Poly-L-Lysine Complex on Herpesvirus hominis Infections in Mice

The effect of treatment with exogenous interferon was compared with those of two interferon inducers, polyriboinosinic-polyribocytidylic acid [poly(I) . poly(C)] and poly(I) . poly(C)-poly-L-lysine complex [poly(ICLC)], in three model Herpesvirus hominis type 2 infections of mice. After intraperitoneal inoculation of H. hominis type 2, all drugs significantly protected animals against death and increased the mean day of death when administered as late as 48 hr after viral inoculation. With intranasal inoculation of H. hominis type 2, pretreatment with poly (I) . poly (C) and poly (ICLC) increased the mean day of death; however, no drug prevented death. In mice inoculated intravaginally, local treatment with exogenous interferon or poly(I) . poly(C) appeared to reduce the mean titers of virus in genital secretions and resulted in earlier clearance of infection in some animals. Systemic treatment of genital H. hominis type 2 infections with all drugs resulted in significant numbers of infected animals surviving the infection, although the mean titers of virus in genital secretions were unchanged. Therapeutic efficacy varied depending on the route of viral inoculation.

Bovine Leukemia Virus Involvement In Enzootic Bovine Leukosis

Enzootic bovine leukosis is a contagious disease induced by bovine leukemia virus (BLV). It is a chronic disease that develops over a long period and can be schematically divided into three phases: (1) from birth to infection (some animals are already infected at birth), (2) from viral infection to tumorous transformation (a number of infected animals do not develop tumors before being slaughtered), and (3) from tumorous transformation to death. Bovine leukotic lymphocytes, kept in vitro in suitable medium, release detectable amounts of BLV. Short-term cultures of leukocytes from cows with persistent lymphocyotsis or long-term cultures of BLV-infected cells were used to study the morphogenesis of BLV, wherein one system was made of degenerating cells, the other made of healthy fast growing cells. Detection of anti-BLV antibodies includes immunodiffusion using p 24 , p 15 , immunofluorescence (IF), complement fixation (CF), and radioimmunoassay. All these methods are indirect detection methods. They detect BLV infection through the immune reaction of the host. The chapter presents the experiments performed to understand the transmission of BLV to the homologous host.

Vaccination Against Dictyocaulus Filaria with Irradiated Larvae

Active anthelmintic immunization, by means of vaccination with irradiated larvae, represents the most recent approach to solution of the problem of control of parasitic diseases. An irradiated vaccine against Dictyocaulus filaria was tested in nearly 2,000 animals in both laboratory and field experiments. In laboratory experiments, doubly-vaccinated lambs were highly resistant to challenge, in comparison with non-vaccinated controls. When challenged on the 15th day after vaccination, 81·8 per cent of vaccinated animals were resistant, and on the 60th day after vaccination 100 per cent were resistant. Field experiments on the infected lambs and sheep established that a post-vaccination decrease took place in both the number of infected animals and the degree of infection. The average percentage for both decreased by about 50 to 60 per cent of the values in the controls at the end of the first pasture season. The epidemiological aspect of dictyocauliasis is discussed as well as the need for procedures for evaluating anthelmintic vaccines.

A study on orange-pigmented non-photochromogenic mycobacteria.

Abstract On the basis of staining, cultural properties, and in vitro sensitivity reactions to certain antimicrobial agents the scotochromogens are unlike the common saprophytic mycobacteria and tubercle bacilli. They form a group distinct from these. Their bacteriologic characteristics are more like those of photochromogens. A notable difference is that photochromogens need light for synthesis of pigment. Resistance to acid-alcohol decolorization, tolerance to p -aminosalicylate and less so to streptomycin, ability to grow on suboptimal media and at room temperatures, and the capacity to form pigment independent of light are useful criteria for identification of scotochromogens. A chronic suppurative inflammatory response was produced in guinea pigs. The histologic picture is not typical of tuberculosis although epithelioid tubercles and/or atypical multinucleated giant cells were present in a number of infected animals occurring particularly in the liver.