CHEMOTHERAPY OF EXPERIMENTAL LEPTOSPIRAL INFECTION IN MICE

A strain of Leptospira zanoni was used to produce chronic renal infections in young white mice. A variant of this strain produced an acute disease with over 50% mortality. The responses of both forms of disease to chemotherapy were studied. When treatment of the acute disease was initiated before jaundice occurred, suitable single doses of streptomycin, chlortetracycline, tetracycline, erythromycin, oxytetracycline and oxytetracycline (in oil) prevented death and chronic renal infection in a high percentage of mice. Bicillin, a long‐acting penicillin preparation, was more effective than other penicillins, but it prevented the development of chronic renal infection in only half the treated mice. Streptomycin was the only antibiotic of which a single administration regularly cured the chronic renal infections: chlortetracycline, tetracycline and oxytetracycline (in oil) were partially effective. Oxytetracycline, chloramphenicol, Bicillin, fortified penicillin, procaine penicillin and potassium penicillin had no permanent action. The suitability of mice as laboratory animals in the study of experimental leptospirosis and the need for complete cure of carriers of chronic renal infection are emphasized. The above findings indicate that streptomycin is the drug of choice for the treatment of leptospirosis in animals, and that it is worthy of further trial in man. 1963 British Pharmacological Societ

Tumour-associated antigens in bovine ocular squamous cell carcinoma: Studies with sera from tumour-bearing animals

Sera from 21 cattle (10 bovine ocular squamous cell carcinoma (BOSCC) bearing and 11 controls) were tested for antibody reactivity against various cultured cells (BOSCC, normal skin and tumours other than BOSCC), by an indirect immunofluorescence technique. Most of the BOSCC sera reacted with autologous and allogeneic BOSCC cells and did not show any significant reactivity with normal skin cells (autologous or allogeneic). These sera when further tested on 7 different allogeneic or xenogeneic tumour cell types (other than BOSCC), showed significant reactivity only with cultured equine sarcoid and cutaneous papilloma cells. Three of the BOSCC sera did not react with autologous BOSCC cells but reacted indiscriminately with all other allogeneic BOSCC, normal cells and other tumour cells. Most of the control sera did not show any significant reactivity against BOSCC cells except sera from one cow bearing ocular papilloma and 2 healthy normals that were in contact with BOSCC bearing animals. This study suggests that BOSCC cells possess tumour associated antigens that are common to most (if not all) BOSCC cells

The pathogenesis of bovine ephemeral fever virus infection of adult mice

Infection of adult mice with small doses of neuro-virulent bovine ephemeral fever virus caused a rapidly fatal encephalitis, the course of which was largely unaffected by treatment with either cyclophosphamide or anti-lymphocyte serum. Athymic mice died earlier than their thymic littermates. Mice could be protected by treatment with defective virus before infection or by passive administration of antibody if given less than 48 h after infection. Taken together these results emphasize the important protective role of antibody present at the time of infection. Viral isolation and immuno-fluorescent studies showed that the virus is confined to the central nervous system. Regular infection of suckling and adult mice by extra-cerebral routes was not possible

Administration of a vaccine prepared from the Australian V4 strain of Newcastle disease virus by aerosol and drinking water

SUMMARY An experimental vaccine containing the avirulent Australian V4 strain of Newcastle disease virus was used to vaccinate 3‐ or 6‐week‐old chickens by aerosol and drinking water application. The chickens lacked maternally derived antibody to Newcastle disease virus. When the vaccine virus was diluted in tap water more than 90% of the infectivity was destroyed immediately. The addition of 0.25% skim milk prevented this loss and there was no loss in distilled water. Rates of inactivation at 37°C were similar in tap water and distilled water and were unaffected by the addition of skim milk. Both methods of vaccination resulted in the production of haemagglutination‐inhibition antibodies which persisted for at least 8 to 12 weeks. The antibody response to aerosol vaccination was significantly better than that following drinking water vaccination. No clinical disease was induced by exposure to vaccine virus. Serum neutralisation antibodies paralleled those detected by haemagglutination‐inhibition in chicks vaccinated once by drinking water. After revaccination through the drinking water, haemagglutination‐inhibition antibodies were boosted temporarily while neutralising antibodies were maintained at an enhanced level. From chickens vaccinated by aerosol, Newcastle disease virus was recovered for 10 days from lungs and for 7 days from tracheas and caecal tonsils. Peak viraemia was detected 2 and 3 days after vaccination while both neutralising and haemagglutination‐inhibition antibodies became detectable 5 days after vaccination