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Biomedical subjects

I M Parsonson

Publications and source records attributed to I M Parsonson.

At least 37 records · Page 2Linked to original sources
PubMed1983

The effect of Tritrichomonas foetus infection on calving rates in beef cattle.

The effect of Tritrichomonas foetus var. brisbane infection on calf production by Hereford cows was determined. The mean number of calves produced by cows that were kept continuously with bulls infected with T. foetus for 3 years was 17.6% less than the mean number produced by cows kept with a non-infected bull. Losses in production due to trichomoniasis occurred each year, but were greatest in the first 2 years in cows experiencing infection for the first time.

Animals↗
PubMed1983

Immunisation of bulls against trichomoniasis.

Studies into the immunisation of bulls against infection with Tritrichomonas foetus showed that subcutaneous administration of vaccines containing killed cells of T foetus in a mineral oil adjuvant prevented the eliminated genital infection in most bulls up to the age of 5 years. Immunisation did not effectively prevent or cure infection in bulls older than 5.5 years.

Age Factors↗
PubMed1983

Bluetongue virus serotype 20 infections in cattle of breeding age.

Ten cattle (6 heifers and 4 bulls) were inoculated with bluetongue virus (BTV) type 20. Clinical signs, antibody responses, and capabilities of these animals to replicate and maintain virus were assessed. The cattle showed no clinical signs of disease, although they did develop antibodies to BTV which showed long-term increasing titers. Virus was intermittently isolated from samples of blood, but not beyond day 21. Virus was not detected in the semen of the bulls, nor isolated from the tissues of the cattle at necropsy except from the genital tract of the 2 bulls which had been killed within 30 days after their inoculation. Gross and microscopic pathologic changes were not seen in any tissues that were attributable to BTV infection. There was no evidence of damage to the reproductive organs or of the development of a latent carrier state in either the heifers or the bulls.

Animals↗
PubMed1982

Bluetongue virus serotypes 20 and 17 infections in sheep: comparison of clinical and serological responses.

The clinical, virological and serological responses of sheep infected with an Australian bluetongue virus (BTV) isolate (serotype 20) were compared to responses in sheep inoculated with an American bluetongue isolate (serotype 17) with which it had shown cross-reactions in serum neutralization tests. In sheep inoculated with BTV 20, clinical signs were very mild and viremia was first detected by day 5; virus was isolated intermittently for a further 2 to 3 days. Neutralizing and precipitating antibodies were first detected in the serum of the sheep between 2 to 3 weeks following inoculation. In contrast, sheep inoculated with BTV 17 showed pyrexia and severe hyperemia of the nasolabial area and oral mucosa from day 7 to 17. Viremia was first detected on day 3 and extended to day 20, while the appearance and titers of serum antibodies was similar in both groups. After challenge with BTV 17 the sheep in both groups remained clinically normal, and virus was not detected in the blood; however, serum neutralizing antibody titers to both viruses increased 2 weeks after challenge and the mean titer of the two groups ranged from 1:250 to 1:640.

Animals↗
PubMed1982

Comparative studies on the growth of Australian bluetongue virus serotypes in continuous cell lines and embryonated chicken eggs.

The replication of cell culture passaged Australian bluetongue virus (BTV) isolates, serotypes 20 (CSIRO19) and 1 (CSIRO156), and an untyped BTV (CSIRO154) was assessed in eight continuous cell lines (one derived from baby hamster kidney cells, BHK-21; three derived from monkey kidney cells, Vero, LLC-MK2 and CV-1P; a foetal ovine lung and a mouse fibroblast cell line, CSL503 and L929, respectively, a Super-Vero-Porcine stable cell line, SVP; and a mosquito cell line, Aedes albopictus cells) and in 11-day-old embryonated chicken eggs (ECE) at different multiplicities of infection. All three viruses replicated in the cell lines tested, maximum extracellular virus yields being attained from BHK-21 cells at high multiplicities of infection (approximately 10 PFU per cell). Also BHK-21 cells produced much higher yields of virus than the other cell lines tested when low multiplicities of infection were used (approximately 10(-4) PFU per cell). All BTV serotypes multiplied in Singh's Aedes albopictus cells with no cytopathogenic effects over the 4 day period tested. The viruses also replicated in 11-day-old ECE; however, the sensitivity of ECE for growth of the Australian serotypes was not as high as has been reported for BTV isolates in other countries. In all cell culture systems and in ECE, BTV1 and BTV20 replicated more efficiently than did CSIRO154 virus.

Aedes↗
PubMed1981

Developmental disorders of the fetus in some arthropod-borne virus infections.

A number of arboviruses have been associated with congenital defects in domestic aminals and man. In this review comparison is made of the temporal association between epidemics of arboviruses affecting man and animals in which there is an obvious relationship between the infection and the fetal defects, and arboviruses which cause no overt clinical symptoms in the vertebrate host but result in deformities of the fetus. The danger to the fetus following the use of live attenuated virus vaccines against several important arbovirus diseases is also examined. It is concluded that arboviruses which are capable of infecting humans or animals without producing overt clinical signs, and attenuated vaccine viruses pose the greatest threat to the fetus.

Animals↗
PubMed1981

Experimental infection of bulls with Akabane virus.

Eight bulls were inoculated with Akabane virus and the clinical effects, development of viraemia and serological response to infection were followed. In addition semen was collected regularly from each bull both before and after inoculation. The bulls had a viraemia which occurred between days 2 and 9 after inoculation and which lasted for three to five days. Virus neutralising antibodies were detected in the serum of all bulls by days 7 to 10. Semen samples were tested for virus by inoculation of tissue cultures and by subcutaneous injection of susceptible cattle. Akabane virus was not detected in the semen using either method. The semen was usually of a standard acceptable for artificial breeding. The results of this study suggest that Akabane virus infection of the bull would not affect reproduction.

Animals↗
PubMed1977

Incidence of Tritrichomonas foetus in young replacement bulls following introduction into an infected herd.

Three hundred 8-year-old Shorthorn and Santa Gertrudis bulls, with a 47% incidence of Tritrichomonas foetus infection in the 30 surveyed, were removed from a herd of approximately 6000 cows and replaced by 325 two-year-old Brahman bulls. A sample of 50 of the replacement bulls was examined at introduction and found to be uninfected. After 2 years, the incidence of infection in a sample of 80 of the replacement bulls was 4%. The results suggests that a major reduction in incidence of infection in extensively managed herds might be achieved by the exclusive use of young bulls for mating.

Age Factors↗
PubMed1977

Studies on the transmission of Tritrichomonas foetus.

Although 2 experiments showed that non-infected bulls can passively transmit Tritrichomonas foestus from infected to non-infected cows during mating, the rates of transmission were low. The results of the second experiment, in which time intervals between services were recorded, suggested that T. foetus was most likely to become established in previously non-infected cows when the interval was less than 20 minutes. Application of 2 X 10(6) active cells of T. foetus to the vulva failed to cause genital infection in 10 cows.

Animals↗
PubMed1977

A dual vaccine for the immunisation of cattle against vibriosis.

Single subcutaneous injections of a mineral oil adjuvant vaccine containing 20 mg dry weight of Campylobacter fetus subsp fetus biotype venerealis cells and 20 mg dry weight of C. fetus subsp fetus biotype intermedius cells per 5 mil dose protected 2- and 3-year-old heifers and 3- and 4-year-old cows against genital infection with either organism.

Animals↗
PubMed1977

Congenital abnormalities in newborn lambs after infection of pregnant sheep with Akabane virus.

Akabane virus (a Bunyavirus) has been associated with epizootics of congenital deformities in cattle, sheep, and goats. Experimental studies using mouse-adapted virus inoculated intravenously into pregnant sheep gave an inapparent infection. Neutralizing antibodies were detected on day 5, and peaks in the titer were seen at days 10 and 48. Ewes infected at day 30 to 36 of pregnancy produced five (31% incidence) deformed lambs. Sera from four of these possessed neutralizing antibodies to Akabane virus before ingesting colostrum. Two lambs had arthrogryposis, hydranencephaly, kyphosis, scoliosis, and brachygnathia; one had micrencephaly; and the other two had porencephaly. The two lambs with arthrogryposis and hydranencephaly also had extensive lesions in other tissues. In the spinal cord there was a marked decrease in the number of ventral horn neurones and a depletion of myelin. Skeletal muscles showed marked atrophy. The medulla of the thymus possessed large Hassall's corpuscles and a reduced number of thymocytes in the cortex. It would appear that the pathogenic effects of Akabane virus are related to the gestational age (30 to 36 days) at which the fetus is infected. Akabane virus can now be included in the growing list of teratogenic viruses and provides an interesting system for studying such congenital diseases.

Animals↗