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Biomedical subjects

I E Anderson

Publications and source records attributed to I E Anderson.

24 records · Page 2Linked to original sources
PubMed1985

Attempted venereal transmission of Chlamydia psittaci in sheep.

Attempts were made to transmit Chlamydia psittaci, the causal agent of enzootic abortion of ewes, in three different ways. Ten ewes were inseminated artificially with freshly collected semen containing 10(5) CELD50 chlamydia. Serological evidence of infection was found two weeks before parturition in nine ewes and the organism was recovered from three of them. By six weeks post partum antibody titres had fallen and were negative in six ewes. Twenty-four hours after service two groups of 10 ewes were infected intravaginally with 10(8) CELD50 and 10(3) CELD50 chlamydia respectively. Positive complement fixation titres were present in the first half of pregnancy in all the ewes in the high dose group but not the low dose group. None of the ewes showed evidence of infection at parturition. Fourteen ewes were served by four rams which had been intravenously infected with 10(8) CELD50 chlamydia four to six days earlier. Following service seroconversion occurred but titres became negative again by late pregnancy. No microbiological evidence of infection was detected in any of the ewes at parturition but complement fixation titres were positive in 12 of 14 ewes sampled six weeks post partum. The 14 ewes were sampled during their pregnancies the next year and none showed any evidence of chlamydial infection. It is concluded that venereal transmission of C psittaci is biologically feasible in sheep, but that under normal systems of flock management in Britain it is unlikely to contribute greatly to the epidemiology of enzootic abortion of ewes.

Abortion, Septic↗
PubMedDate not supplied

Characterization of the immune response in the placenta of cattle experimentally infected with Neospora caninum in early gestation.

A serial examination of three groups of cattle infected intravenously (iv) (Group 1, n=8) or subcutaneously (sc) (Group 2, n=8) with live Neospora caninum tachyzoites or with VERO cells (Group 3, n=8) at 70 days' gestation was carried out and the nature of the inflammatory responses in the placenta and the presence of parasite antigen were analysed. Immune cells expressing CD3, CD4, CD8, gamma delta (gammadelta) T-cell receptors (TCR), CD79alpha cytoplasmic (cy) (B cells) and NKp46 [natural killer (NK) cells] antigens were identified immunohistochemically and cells expressing mRNA for interferon-gamma (IFN-gamma) were labelled by in-situ hybridization. Intravenous inoculation caused mortality in all fetuses from 28 days post-inoculation (dpi) onwards. Subcutaneous inoculation caused mortality in 50% of the animals by 28dpi. Pathological changes in the placenta consisted of necrosis of fetal placental villi, necrosis and inflammation in adjacent areas of the maternal septum and inflammation at the base of the maternal caruncle. The inflammatory infiltrate consisted mainly of CD3(+) lymphocytes, dominated by CD4(+) and gammadelta TCR(+) cells, with CD8(+) cells present to a lesser extent. The results from the control group indicated fewer NK cells than those occurring in the placenta of human beings or mice. Infiltration of CD4(+) cells and NKp46(+) cells was observed in the caruncular base and septa 14 days after infection, whereas infiltration of gammadelta TCR(+) cells was observed from 28 dpi onwards. To our knowledge this is the first report on the presence and distribution of NK cells in the bovine placenta. Maternal inflammatory cells expressing mRNA for IFN-gamma were identified in animals inoculated with parasites iv or sc at 14 and 28 dpi, respectively. In the sc-inoculated dams with live fetuses at 28, 42 and 56dpi, there was no evidence of parasite antigen, infiltration of immune cells or production of IFN-gamma, suggesting that the parasite had not reached the placenta. The exact cause of fetal death was not established. Tissue destruction by the parasite may have occurred; in addition, there may have been a T helper 1 (Th-1) immune response to the neospora infection at the materno-fetal interface, resulting in infiltrations of CD4T cells, gammadelta T cells and NK cells and the subsequent production of IFN-gamma. It is possible that a pro-inflammatory Th-1 response early in gestation protects the dam by eliminating the parasite; however, it may lead to destruction of the placental tissues themselves and thus be incompatible with fetal survival.

Animals↗
PubMedDate not supplied

Ovine chlamydial abortion: characterization of the inflammatory immune response in placental tissues.

Ovine chlamydial abortion is a serious cause of fetal mortality in several sheep-rearing countries. The causal agent, Chlamydophila abortus (Chlamydia psittaci), does not generally induce clinical signs in the ewe other than abortion; this is associated with macroscopically visible damage in the placenta, which may be inflamed and thickened. To investigate the nature of the placental inflammation, seven pregnant sheep were inoculated subcutaneously at 70 days' gestation with C. abortus (strain S 26/3). A further five pregnant sheep received control inoculum by the same route at the same stage of pregnancy. Three of the infected ewes produced stillborn lambs and four produced live lambs. Lesions characteristic of chlamydial infection were present in all placentas except for two from one ewe that gave birth to twins. Histopathological examination of placental tissues from aborted fetuses showed a mixed inflammatory cell infiltrate with vasculitis and thrombosis in the mesenchyme of the intercotyledonary membranes. Cells expressing the macrophage-associated molecule CD 14 were found to be numerous, as were cells expressing major histocompatibility complex class II (MHC II) molecules. Many cells expressing messenger RNA (mRNA) encoding for tumour necrosis factor-alpha (TNF-alpha) were demonstrated, but few cells expressing interferon gamma mRNA and none expressing interleukin-4 mRNA were detected. The fetal immune response included small numbers of CD4+ and CD8+ cells, gamma delta T cells and B cells. It is concluded that abortion is the result of several factors, including destruction of tissue by C. abortus, vascular thrombosis, and an inflammatory response by the fetus. Production of TNF-alpha by fetal macrophages expressing MHC II molecules may be of considerable significance in the pathogenesis of abortion.

Abortion, Veterinary↗