Biomedical subjects

J M Trout

Publications and source records attributed to J M Trout.

At least 37 records · Page 2Linked to original sources

PubMed1998

Detection of Cryptosporidium oocysts and Giardia cysts in the tissues of eastern oysters (Crassostrea virginica) carrying principal oyster infectious diseases.

The potential cross-reactivity of the combined Cryptosporidium/Giardia direct immunofluorescence antibodies (IFA) of MERIFLUOR and HYDROFLUOR-COMBO tests was examined against tissues containing known developmental stages of 12 pathogens causing the principal infectious diseases in oysters. Spores of Haplosporidium nelsoni and Haplosporidium costale produced positive acid-fast stain (AFS) reactions similar in intensity to Cryptosporidium parvum oocysts. Hexamia nelsoni trophozoites produced positive IFA reactions in both IFA tests; however, the intensity of fluorescence was considerably lower and the fluorescein-staining pattern different than those of Giardia cysts. The applicability of AFS for screening oysters for Cryptosporidium oocysts is low, and positive identification of Cryptosporidium oocysts cannot be accomplished based on the AFS. Presumptive IFA identification of the Cryptosporidium oocysts or Giardia cysts in the oyster tissue should fulfill 3 criteria, i.e., bright-green fluorescence of the same intensity as C. parvum oocysts and Giardia cysts in the positive control, correct size and shape of the fluorescein-stained objects, and oocyst or cyst shell clearly visible.

Animals↗

PubMed1998

Infectivity of Cryptosporidium parvum oocysts stored in water at environmental temperatures.

Oocysts of Cryptosporidium parvum obtained from calves were cleaned of fecal debris by density gradient centrifugation and suspended in deionized water in microcentrifuge tubes. The tubes were placed in circulating water baths at temperatures of -10, -5, 0, 5, 10, 15, 20, 25, 30, or 35 C, and 2 tubes were removed from each water bath 1, 2, 4, 8, 12, 16, 20, and 24 wk later. Oocysts from 1 tube were administered at the rate of 1.5 x 10(5) oocysts per mouse to 2 litters of neonatal BALB/c mice and were considered infective when developmental stages were found in histologic sections of mouse gut and/or a positive polymerase chain reaction (PCR) was obtained for C. parvum DNA in mouse ileum. The second tube was held at -70 C until tubes from all time periods were available, then oocysts within the tubes were assayed for amylopectin concentration. Oocysts held at -10 C were infectious up to 1 wk of storage, and those held at -5 C were infectious up to 8 wk of storage, as determined by PCR but not histology. Oocysts held at 0, 5, 10, 15, and 20 C were still infectious after 24 wk of storage. By microscopic examination of mouse tissue, oocysts held at 20 C infected only 1 of 10 mice after 24 wk of storage, and the number of developmental stages began declining after 4 wk of storage; those held at 25 and 30 C each produced infections up to 12 wk after storage in 1 of 10 mice with reduced numbers of developmental stages beginning 4 wk after storage. Those held at 35 C produced light infections in 2 of 10 mice only up to 1 wk of storage. Amylopectin concentration decreased with increasing length of storage time or temperature. These findings provide a guide for estimating the potential duration of oocyst infectivity within a wide range of environmental temperatures and demonstrate the relationship between amylopectin concentration and infectivity.

Amylopectin↗

PubMed1997

Potential Role of the Eastern Oyster, Crassostrea virginica, in the Epidemiology of Cryptosporidium parvum.

Oysters were placed in an aquarium containing artificial seawater, and Cryptosporidium parvum oocysts were added. Oocysts were later found in the gill washings, hemocytes, and gut contents of the oysters. Hemocytes containing oocysts were intubated into four mice. C. parvum stages developed in the ileal epithelia of all of the mice, indicating that the oocysts in the hemocytes remained infective.

Journal Article↗

PubMed1997

In vitro interactions between hemocytes of the eastern oyster, Crassostrea virginica Gmelin, 1791 and Cryptosporidium parvum oocysts.

It was demonstrated by an in vitro slide phagocytosis assay that hemocytes of the Eastern oyster, Crassostrea virginica Gmelin, 1791 are capable of rapid recognition and internalization of infectious Cryptosporidium parvum (AUCP-1 strain) oocysts. The incubation of hemocyte monolayers (8.5 x 10(4) cells) that had received 6.8 x 10(5) or 3.4 x 10(5) oocysts was arrested at 5, 15, 30, 60, 90, and 120 min and the oocytes detected by acid-fast stain and immunofluorescent antibody (IFAT). An average of 20.5, 38.3, 50.2, 58.9, 69.0, and 75.0% oocysts were phagocytosed after 5, 15, 30, 60, 90, and 120 min, respectively. The intensity of fluorescence of phagocytosed oocysts significantly decreased over time (P < 0.01), and their round shape was altered. The number of cells containing oocysts and the mean number of ingested oocysts (range: 1.2-4.5 per cell) increased significantly over time (P < 0.01), whereas the numbers of nonphagocytosed oocysts that were adherent to the glass slides significantly decreased (P < 0.05). By extrapolation, the results indicate that Cr. virginica is capable of internalizing up to 6.4 x 10(6) Cryptosporidium oocysts per ml of its hemolymph.

Analysis of Variance↗

PubMed1996

T lymphocyte roles during Eimeria acervulina and Eimeria tenella infections.

This study evaluated the effects of selective depletion of T lymphocytes on Eimeria infections in chickens. Cell depletions were initiated in day- or week-old Hyline SC strain chickens using intra-peritoneal injections of monoclonal antibodies to CD4, CD8, or T cell receptor (TCR) alpha/beta. Control chickens received injections of irrelevant monoclonal antibody or phosphate buffered saline (PBS). Following the establishment of cell depletion, chickens were infected orally with E. acervulina or E. tenella, 1 x 10(4) oocysts for primary infections and 2 x 10(5) oocysts for secondary infections. Chickens treated with anti CD4 monoclonal antibody produced significantly more oocysts than controls following primary E. tenella but not E. acervulina infections. Development of resistance to challenge infection was unaffected. These results suggest that CD4+ lymphocytes are important in controlling primary infection with E. tenella. Chickens treated with anti-CD8 or anti-TCR alpha/beta monoclonal antibodies produced significantly fewer oocysts than controls following primary infection but significantly more oocysts than controls following secondary infection with both E. tenella and E. acervulina. Additionally, anti-CD8 treatment abrogated resistance to challenge infection. CD8-depleted chickens may exhibit decreased oocyst production following primary infection due to a lack of CD8+ lymphocytes to serve as transporting cells for sporozoites. The abrogation of resistance to secondary infection in CD8- and TCR alpha/beta-depleted chickens suggests that these cells are necessary for the development of protective immunity to coccidia.

Animals↗

PubMed1996

Changes in blood and spleen lymphocyte populations following antigen challenge in immature male chickens.

1. The effects of antigen (Ag) injection on the distribution of lymphocyte populations of Cornell K-strain male chickens were studied. 2. Two experiments were conducted. In the first, chickens were injected with Brucella abortus (BA), a purported T-independent antigen. In the second, chickens were injected with sheep red blood cells (SRBC), a T-dependent antigen. Peripheral blood lymphocytes (PBL) and spleen lymphocytes isolated at 0, 3, 6, 9, 12 and 24 h following Ag injection were stained with monoclonal antibodies (mAb) detecting B-lymphocytes, CD4+ and CD8+ cells. 3. B-lymphocytes in the blood or spleen showed no significant changes following either BA or SRBC injection. In contrast, CD4+ cells were decreased in the blood and increased in the spleen following BA and SRBC injections. CD8+ cells were decreased in both blood and spleen following BA injection but were unchanged in either blood or the spleen following SRBC injection. 4. These results indicate that there is a change in both spleen and circulating lymphocyte populations, especially T-helper cells, following Ag injection. T-helper cells are apparently the primary population involved in the initiation of humoral immunity.

Aging↗

PubMed1996

Gaseous disinfection of Cryptosporidium parvum oocysts.

Purified oocysts of Cryptosporidium parvum suspended in approximately 400 microliters of phosphate-buffered saline or deionized water in microcentrifuge tubes were exposed at 21 to 23 degrees C for 24 h to a saturated atmosphere of ammonia, carbon monoxide, ethylene oxide, formaldehyde, or methyl bromide gas. Controls were exposed to air. Oocysts in each tube were then rinsed and resuspended in fresh, deionized water, and 1 million oocysts exposed to each gas were orally administered to each of three to six neonatal BALB/c mice in replicate groups. Histologic sections of ileum, cecum, and colon tissues taken from each mouse 72 h after oral administration of oocysts were examined microscopically to determine if infection had been established. All 15 mice given oocysts exposed to carbon monoxide had numerous developmental stages of cryptosporidium in all three intestinal segments. Of 10 mice given oocysts exposed to formaldehyde, 6 had a few developmental stages of cryptosporidium in the ileum. No mice given oocysts exposed to ammonia, ethylene oxide, or methyl bromide were found to be infected. These findings indicate the efficacy of these low-molecular-weight gases (ammonia, ethylene oxide, and methyl bromide) as potential disinfectants for C. parvum oocysts where soil, rooms, buildings, tools, or instruments might be contaminated.

Ammonia↗

PubMed1996

Avian gut-associated lymphoid tissues and intestinal immune responses to Eimeria parasites.

Coccidiosis, an intestinal infection caused by intracellular protozoan parasites belonging to several different species of Eimeria, seriously impairs the growth and feed utilization of livestock and poultry. Host immune responses to coccidial infection are complex. Animals infected with Eimeria spp. produce parasite-specific antibodies in both the circulation and mucosal secretions. However, it appears that antibody-mediated responses play a minor role in protection against coccidiosis. Furthermore, there is increasing evidence that cell-mediated immunity plays a major role in resistance to infection. T lymphocytes appear to respond to coccidial infection through both cytokine production and a direct cytotoxic attack on infected cells. The exact mechanisms by which T cells eliminate the parasites, however, remain unclear. Although limited information is available on the intestinal immune system of chickens, gut lymphoid tissues have evolved specialized features that reflect their role as the first line of defense at mucosal surfaces, including both immunoregulatory cells and effector cells. This review summarizes our current understanding of the avian intestinal immune system and mucosal immune responses to Eimeria spp., providing an overview of the complex cellular and molecular events involved in intestinal immune responses to enteric pathogens.

Animals↗

PubMed1995

Effects of in vitro corticosterone on chicken T- and B-lymphocyte proliferation.

1. The effects of corticosterone and the time of its addition to cultures, on concanavalin A (Con-A) and pokeweed mitogen (PWM)-induced lymphocyte proliferation were studied. 2. Peripheral blood lymphocytes (PBL) were isolated from Cornell K-strain Single Comb White Leghorn immature male chickens and cultured with various concentrations of Con-A or PWM. Corticosterone, in different concentrations, was added to the cultures either 2 h before or 2 h after the addition of the respective mitogen. 3. Addition of corticosterone 2 h before the mitogens caused a significant suppression of lymphocyte proliferation in response to both Con-A and PWM stimulation. Also addition of corticosterone 2 h after the mitogens caused significant suppression of proliferation in response to both mitogens; however, the degree of suppression was not as great. 4. The results indicate that after early activation events are initiated by the mitogens, lymphocytes are less sensitive to the effects of corticosterone. Because less suppression was seen in the cultures preincubated with PWM than those with Con-A, it is likely that there are different sensitivities to corticosterone in the cell populations that respond to these mitogens.

Animals↗

PubMed1995

Eimeria acervulina infection: evidence for the involvement of CD8+ T lymphocytes in sporozoite transport and host protection.

Host-parasite interactions during coccidial infection are complex, and host responses leading to parasite elimination are not well understood. Interactions between host cells and parasites were investigated using two-color immunofluorescent staining of duodenal tissue infected with Eimeria acervulina. Tissues were removed from TK strain chickens 24, 48, and 72 h after primary infection with 2.5 x 10(7) normal or irradiated oocysts and also following secondary infection with 2.5 x 10(7) normal oocysts. The tissues were embedded in freezing compound, frozen, sectioned, and fixed in cold acetone. Sections were stained with monoclonal antibodies to identify CD4+, CD8+, Ig+, and Bu1a+ lymphocytes, as well as macrophages and parasites. At 24 h after all infections, sporozoites were seen primarily in CD8+ lymphocytes and macrophages. Many CD8+ lymphocytes were seen at all times in infected tissues and frequently appeared to be in contact with infected epithelial cells. Sporozoites were occasionally seen in CD4+ lymphocytes but none were noted in Ig+ or Bu1a+ lymphocytes. Meront development was extensive after primary infection with normal oocysts, sparse after primary infection with irradiated oocysts, and moderate after secondary infection.

Animals↗

PubMed1994

CD8+ T cell-coccidia interactions.

Host responses to coccidian parasites involve many facets of the immune system, including antigen-specific as well as antigen-nonspecific components. Hyun Lillehoj and James Trout here review the evidence that cell-mediated responses are probably the main line of defense against coccidial infection.

Journal Article↗

PubMed1994

The effects of adrenocorticotropic hormone and heat stress on the distribution of lymphocyte populations in immature male chickens.

This study investigated the effects of heat stress and adrenocorticotropic hormone (ACTH) on the distribution of lymphocyte populations. Two experiments were conducted; each used 12-wk-old Cornell K-strain male chickens. In Experiment 1, birds were exposed to a temperature of 35 C, 6 h/d for 5 d and control birds were maintained at 24 C. In Experiment 2, birds received daily i.m. injections of 50 IU/kg body weight of ACTH for 5 d and control birds received .9% saline. On Day 6, blood and spleens were collected and lymphocytes were isolated. Indirect immunofluorescent labeling of lymphocytes were performed to detect B lymphocytes, CD4+ cells, and CD8+ cells. Neither ACTH injection nor heat stress affected percentages of B lymphocytes in the blood or the spleen. The CD4+ cells decreased significantly in the blood of ACTH-injected and heat-stressed birds and significantly increased in the spleens of heat-stressed birds. The CD4+ cells in the spleens of ACTH-injected birds did not differ from controls. The CD8+ cells significantly declined in the blood following both ACTH injection and heat stress and significantly increased in the spleen of the ACTH-injected birds but did not differ from controls in the heat-stressed birds. These results indicate that stress factors lead to redistribution of different lymphocyte populations.

Adrenocorticotropic Hormone↗

PubMed1993

The endocrine function of the immune cells in the initiation of humoral immunity.

The endocrine functions of different hormones are well documented. Recently, however, evidence of the immune function of several hormones has been accumulated. These findings raised the possibility that immune cells might secrete hormones and in turn self-regulate different immune functions. Indeed, immune cells have been found to secrete different peptide and protein hormones. Adrenocorticotropin hormone (ACTH) is the most studied and was found to be secreted by lymphocytes. In the present authors' laboratory, it was found that not only do lymphocytes secrete ACTH but also that circulating concentrations of corticosterone increased following antigen challenge. It was also observed that at the time of the increased corticosterone, there was a redistribution of different lymphocyte subpopulations from the blood to spleen, the site of antigen presentation and antibody production. It was concluded that the endocrine function of lymphocytes might be important in the initiation of antibody production in chickens.

Adrenocorticotropic Hormone↗

PubMed1993

Evidence of a role for intestinal CD8+ lymphocytes and macrophages in transport of Eimeria acervulina sporozoites.

The objective of this study was to identify host immune cells interacting with Eimeria sporozoites in the intestine. One-week-old SC strain chickens were infected with 2 x 10(7) sporulated Eimeria acervulina oocysts. Twenty-four hours postinfection, duodenal sections were removed, imbedded in Tissue-Tek compound, and frozen. After sectioning, tissues were stained with monoclonal antibodies to identify CD4+, CD8+, Ig+, and Bula+ lymphocytes, macrophages, and sporozoites; 28% of the sporozoites were in CD8+ cells, 28% in macrophages, and 12% in CD4+ cells. Sporozoites were not seen in Ig+ or Bula+ cells. These findings suggest that sporozoite transport most likely occurs in T lymphocytes and macrophages.

Animals↗

PubMed1988

Changes in the profiles of circulating white blood cells, corticosterone, T3 and T4 during the initiation of humoral immunity in immature male chickens.

Eight-week-old male White Leghorn chickens were injected intravenously with either 0.1 ml of Brucella abortus (BA) or saline. Blood samples were collected before injection, 1 hr, 3 hr, 6 hr, 12 hr, 24 hr, and then daily for the following 6 days after the injection. Total white blood cells (WBC), differential counts and corticosterone (CS), T3 and T4 levels were measured in all blood samples. These data represented the results obtained from the primary response. To obtain data for the secondary response, the same birds were injected 4 weeks following the first challenge and the same procedure was followed. During primary and secondary responses, circulating lymphocytes and monocytes decreased significantly 3 hr following BA injection and then increased steadily and reached a peak approximately 5 days post-BA injection, however, circulating heterophils increased significantly 6-12 hr and returned to normal levels 2 days post-BA injection. Serum corticosterone increased significantly 3 hr following BA injection. Serum T3 decreased significantly 3 to 12 hr then increased significantly 2 days following BA injection. There were no significant changes in any of the measurements following saline injection. Correlations between circulating hormones and white blood cells were calculated and are reported. These results indicate that an early step in the initiation of humoral immunity is probably an increase in serum CS. This increase in CS is followed by a decrease in circulating lymphocyte and monocyte numbers. These decreases may be the result of lymphocyte trapping in secondary lymphoid organs. This series of events may occur to modulate and activate the immune response.

Animals↗

PubMed1988

Changes in heterophils following antigen injection in immature male chickens.

Eight-week-old Single Comb White Leghorn male chickens were injected intravenously with either .1 mL Brucella abortus (BA) or saline. Blood samples were drawn at 0 and 12 h postinjection and were examined for heterophil numbers and morphology. Differences between numbers of circulating heterophils/mm3 blood were not significant for saline and BA-treated birds at time zero. However, 12 h following injection, heterophil numbers in BA-treated birds were significantly (P less than .05) greater than those in saline-treated birds. Heterophil appearance took two forms: in the first form, granules were small, round, and strongly eosinophilic; in the second form, the granules were large, rod-shaped and more basophilic in staining. These changes indicate the possible involvement of heterophils in the initiation of a humoral immune response through enhancement of some secretory function.

Animals↗

PubMedDate not supplied

Rotifers ingest oocysts of Cryptosporidium parvum.

Six genera of rotifers including Philodina, Monostyla, Epiphanes, Euchlanis, Brachionus, and Asplanchna were exposed to oocysts of Cryptosporidium parvum cleaned of fecal debris. Unstained oocysts and those stained with fluorescein-conjugated monoclonal antibody were added to suspensions of viable rotifers and were examined by phase-contrast, differential interference contrast, and fluorescence microscopy. Rotifers of all six genera were observed ingesting oocysts. A maximum of 25 oocysts was observed in the stomachs of Eauchlanis and Brachionus. Euchlanis and Epiphanes were observed excreting boluses containing up to eight oocysts. It was not determined whether rotifers digested or otherwise rendered oocysts nonviable.

Animals↗

PubMedDate not supplied

Cryptosporidium parvum in oysters from commercial harvesting sites in the Chesapeake Bay.

Oocysts of Cryptosporidium parvum, a zoonotic waterborne pathogen, can be removed by bivalve molluscs from contaminated water and retained on gills and in hemolymph. We identified oocysts of C. parvum in oysters from seven sites in the Chesapeake Bay area. These findings document the presence of C. parvum infectious for humans in oysters intended for human consumption.

Animals↗