Influence sexual dimorphism on the persistence of blood parasites in infected Calomys callosus

Gender has long been known to be a contributory factor in the incidence and progression of disorders associated with immune system disregulation. The aims of this experiment were to verify the influences of sexual dimorphism on the persistence of blood parasites out of the acute phase of infection. Male and female Calomys callosus were separated and infected with two strains of Trypanosoma cruzi, and let age until 120 days. Xenogiagnostic, culture of organs and blood, histopathology and lytic antibody percentages were evaluated on late chronic phase. Xenodiagnosis, hemoculture and lytic antibody percentages were positive from 45 until 120 days. For both strains in adrenal and heart, amastigote burdens were present until 45 days, scarcely found on 60 days and absent on 120 days. Steroid hormones, although having a protective role, does not enable animals to get completely rid of the infection. Even without showing apparent signs of pathological unbalance, parasites persists, hidden throughout the host’s body.     

Influence sexual dimorphism on the persistence of blood parasites in infected Calomys callosus

Gender has long been known to be a contributory factor in the incidence and progression of disorders associated with immune system disregulation. The aims of this experiment were to verify the influences of sexual dimorphism on the persistence of blood parasites out of the acute phase of infection. Male and female Calomys callosus were separated and infected with two strains of Trypanosoma cruzi, and let age until 120 days. Xenogiagnostic, culture of organs and blood, histopathology and lytic antibody percentages were evaluated on late chronic phase. Xenodiagnosis, hemoculture and lytic antibody percentages were positive from 45 until 120 days. For both strains in adrenal and heart, amastigote burdens were present until 45 days, scarcely found on 60 days and absent on 120 days. Steroid hormones, although having a protective role, does not enable animals to get completely rid of the infection. Even without showing apparent signs of pathological unbalance, parasites persists, hidden throughout the host’s body.     

Effect of steroid hormones on the innate immune response induced by Staphylococcus aureus in the goat mammary gland

The objective of this study was to compare the dynamics of innate immune components after intramammary infusion of Staphylococcus aureus (SA) under conditions of high oestrogen and high progesterone in goats. In one group (“E‐group”), controlled internal drug release (CIDR) devices were inserted intravaginally from days ?11 to ?4. Prostaglandin F2α was administered immediately after removal of the CIDR device at day ?3, and then oestradiol benzoate (E) was injected intramuscularly once a day from days ?2 to 3. Heat‐inactivated SA was then administered via intramammary infusion to the left udder at day 0, whilst only saline was infused to the right udder as a control. In a second group (“P‐group”), CIDR devices were inserted intravaginally from days ?3 to 7 and SA was infused at day 0 in the same way as in the E‐group. The milk yield and the concentration of innate immune components (somatic cell count (SCC), lactoferrin (LF), S100A7 and goat ß‐defensin 1 (GBD‐1)) in the milk were measured. Milk yield decreased drastically in both SA and control udders in the E‐group, whereas the P‐group exhibited increased milk yield in both SA and control udders. SCC increased after SA infusion in both E‐ and P‐groups, although it was higher in the E‐group than in the P‐group. There was no significant change in LF concentration in the E‐group, but a decrease was observed in the P‐group. Concentrations of S100A and GBD‐1 were significantly increased after SA infusion in the E‐group but not in the P‐group. These results suggest that E enhances the innate immune response induced by SA in the goat mammary gland. This effect may be due to the reduction in milk yield and upregulation of innate immune components.     

Suppression of immune response to sheep red blood cells in rats experimentally infected with Trypanosoma brucei gambiense

A direct haemagglutination assay for antibodies to sheep red blood cells (SRBC) was used to assess the response of rats infected with Trypanosoma brucei gambiense. Whereas uninfected rats showed an efficient primary and secondary immune response to SRBC, trypanosome-infected rats displayed depressed antibody response starting about six days after infection. Infected rats failed to respond to a challenge dose of SRBC given 14 days after infection while uninfected control animals responded with an increased level of antibody production. These observations showed that T. b. gambiense infection inhibited both primary and secondary immune response to SRBC in rats. The result of this experiment is very important with regard to serological methods used to detect increasing levels of antibody production for diagnosis of diseases caused by bacterial and viral pathogens. In a concurrent trypanosome infection such increasing antibody levels would not be observed, leading to inaccurate diagnosis. Thus trypanosomiasis infection should be excluded under field conditions before the value of a serological diagnosis can be fully utilized.     

Specific humoral and cellular immunity induced by Trypanosoma cruzi DNA immunization in a canine model

Chagas disease has a high incidence in Mexico and other Latin American countries. Because one of the most important known methods of prevention is vector control, which has been effective only in certain areas of South America, the development of a vaccine to protect people at risk has been proposed. In this study, we assessed the cellular and humoral immune response generated following immunization with pBCSP and pBCSSP4 plasmids containing the genes encoding a trans-sialidase protein (present in all three forms of T. cruzi) and an amastigote specific glycoprotein, respectively, in a canine model. Thirty-five beagle dogs were divided randomly into 5 groups (n = 7) and were immunized twice intramuscularly with 500 μg of pBCSSP4, pBCSP, pBk-CMV (empty plasmid) or saline solution. Fifteen days after the last immunization the 4 groups were infected intraperitoneally with 500 000 metacyclic trypomastigotes. The fifth group was unimmunized/infected. The parasitaemia in the immunized/infected dogs was for a shorter period (14 vs. 29 days) and the parasite load was lower. The concentration of IgG1 (0.612 ± 0.019 O.D.) and IgG2 (1.167 ± 0.097 O.D.) subclasses was measured (absorbance) 15 days after the last immunization with both recombinant plasmids, the majority of which were IgG2. The treatment of parasites using the serum from dogs immunized with pBCSP and pBCSSP4 plasmids produced 54% (± 11.8) and 68% (± 21.4) complement-mediated lysis, respectively. At 12 h post immunization, an increase in cytokines was not observed; however, vaccination with pBCSSP4 significantly increased the levels of IFN-γ and IL-10 at 9 months post-infection. The recombinant plasmid immunization stimulated the spleen cell proliferation showing a positive stimulatory index above 2.0. In conclusion, immunization using both genes effectively induces a humoral and cellular immune response.     

Plasma concentrations of steroid hormones in sows infected experimentally with Leptospira pomona or porcine enterovirus strain T1 in late gestation

Plasma levels of progesterone, corticosteroids and oestrone were determined during the late stages of pregnancy in four sows experimentally infected with Leptospira pomona and in a group of three sows in which fetuses were inoculated in utero with a strain of porcine enterovirus. Only one of the seven infected sows farrowed at full term. All fetuses were dead and delivery was prolonged in litters infected with the virus. In the sows with leptospirosis almost all piglets were expelled dead or in a weak condition. The amounts of progesterone in plasma were within the normal range and showed a decrease shortly before abortion similar to that observed before parturition in normal animals. The elevation in plasma corticosteroids at normal parturtion was not seen at abortion. An irregular pattern with rising levels of plasma oestrone was found in most sows. Peak levels of oestrone were usually reached close to the time of delivery, but occured earlier in most sows which aborted well before term. In conclusion differences were noted between the endocrine patterns in normal parturition and in abortion caused by infectious agents in sows.     

Comparison of the kinetics of the specific cellular immune response to duck hepatitis B virus in infected and immune ducks.

The kinetics of the cell mediated immune response by ducks acutely and chronically infected with, or immune to infection by duck hepatitis B virus (DHBV) was determined. This was measured by an antigen specific blastogenesis assay to duck hepatitis B surface antigen (DHBsAg) and duck hepatitis B core antigen (DHBcAg) using peripheral blood mononuclear cells (PBMC). The three outcomes of acute infection by DHBV were either clearance from both serum and liver, clearance from serum but not liver, or the development of persistent viraemia. Acutely infected ducks that failed to clear the infection also failed to develop a significant cellular immune response to both antigens. Ducks with chronic infection acquired as neonates or as the result of the failure to clear acute infection had an increasing cellular immune response over time. Two groups of immune ducks were examined. These were either ducks that had become immune following infection or that had been vaccinated. Both groups of ducks demonstrated significant cellular responses following challenge with DHBV irrespective of the level of their responses before challenge. However, there was a reduction in the response of their PBMC over a 4-week-period postchallenge. The range of cellular immune responses to DHBV antigens observed in this study has a number of counterparts in hepatitis B infection of humans. Coupled with the defined clinical outcomes that can be established in the duck/DHBV model, further study of the cellular immune response to DHBV is warranted.     

Effects of human chorionic gonadotrophin and castration on plasma gonadal steroid hormones of the dog

An intramuscular injection of 500 I.U. of human chorionic gonadotrophin resulted in an increase of plasma testosterone and progesterone concentrations in the intact male dog, but had no effect on plasma 17B-estradiol concentration. Castration caused a rapid decrease in concentration of testosterone, progesterone, and 17B-estradiol, indicating that the tests were the major organs producing these hormones in the male dog.     

Effects of ageing and gonadal steroid hormones on prolagtin concentration in the anterior pituitary of the chicken

1. Effects of ageing and gonadal steroid hormones on pituitary prolactin (PRL) concentration in the chicken were investigated.

2. No difference was found in the qualitative electrophoretic patterns of the anterior pituitary homogenates at different ages and between the sexes.

3. Pituitary PRL concentrations in males were generally higher than in females.

4. Pituitary PRL concentrations in castrated immature cockerels were higher than in intact birds, while PRL concentration was depressed by the injection of testosterone propionate or oestradiol benzoate.

5. Prolactin concentration in intact immature cockerels was decreased by daily injection of testosterone or oestradiol for 3 weeks but not by injection of the hormones for 1 week.     

Effect of tea tree oil (Melaleuca alternifolia) on the longevity and immune response of rats infected by Trypanosoma evansi

This study aimed to evaluate the effect of tea tree oil (TTO – Melaleuca alternifolia) on hepatic and renal functions, and the immune response of rats infected by Trypanosoma evansi. A pilot study has shown that rats treated with TTO orally (1 ml kg⁻¹) had increased survival rate without curative effect. In order to verify if increased longevity was related to a better immune response against T. evansi when using tea tree oil, a second experiment was conducted. Thus, twenty-four rats were divided into four groups. The groups A and B were composed of uninfected animals, and the groups C and D had rats experimentally infected by T. evansi. Animals from the groups B and D were treated orally with TTO (1 ml kg⁻¹) for three days. Blood samples were collected to verify humoral response analysis for immunoglobulins (IgA, IgM, IgE, and IgG) and cytokines (TNF-α, INF-γ, IL-1, IL-6, IL-4, and IL-10) at days 0, 3, 5 and 15 post-infection (PI). TTO treatment caused changes in the immunoglobulins and cytokines profile, as well as the course of T. evansi infection in rats. It was found that the TTO was not toxic, i.e., hepatic and renal functions were not affected. Therefore, it is possible to conclude that TTO influences the levels of inflammatory mediators and has trypanocidal effect, increasing life expectancy of rats infected by T. evansi.     

Antibody and lymphoblastogenic responses of dogs experimentally infected with Trypanosoma cruzi isolates from North American mammals

The humoral and cellular immune responses of dogs infected with either a non-pathogenic Trypanosoma cruzi isolated from a North American dog (Tc-D) or a pathogenic T. cruzi isolate from an opossum (Tc-O) were studied over a 240 day period. Antibody to T. cruzi epimastigote antigens prepared from Tc-O or Tc-D isolates were first detected by ELISA by Day 26 post infection (PI), peaked by day 175 PI and remained elevated throughout the experimental period in both Tc-O and Tc-D infected dogs. Differences in antibody levels between infected groups were not detected. Western blot analyses were performed using Tc-O and Tc-D epimastigote antigens probed with pooled sera and sera from individual Tc-O and Tc-D infected dogs prior to infection (Day 0), and during the acute (Day 16-35 PI), indeterminate (Day 50-135 PI) and chronic (Day 235 PI) stages of infection. Generally, the patterns, number of protein bands, and temporal appearance of the protein bands identified by pooled sera and sera from individual dogs within each antigen preparation were similar. However, similarities and differences were present in antibody responses between sera from Tc-O and Tc-D infected dogs. Blastogenic responses of peripheral blood mononuclear cells (PBMC) from Tc-O and Tc-D infected dogs to mitogens (concanavalin A, phytohemagglutinin and pokeweed) were not significantly different from controls at any time during the experimental period. The PBMC from both groups of dogs were unresponsive to epimastigote antigens during the acute stage of infection. Statistically significant differences (P less than 0.05) in PBMC responsiveness from controls were observed on Days 70 and 175 PI. Responses decreased to pre-infection levels by Day 240 PI. These studies demonstrate that although two North American T. cruzi isolates have markedly different virulence for dogs, some aspects of their cellular and humoral immune responses are similar while other responses, such as antibody recognition of specific T. cruzi antigens, vary.     

Ovarian activity and pregnancy in the Siberian tiger, Panthera tigris altaica, assessed by fecal gonadal steroid hormones analyses

Feces were collected from two female and one male Siberian tigers, Panthera tigris altaica. Steroid hormones were extracted from lyophilized feces and quantified by enzyme immunoassay. The fecal contents of estradiol-17beta (E(2)) and testosterone in the females and male, respectively, changed markedly throughout the year. The fecal E(2) contents of females Nos. 179 and 238 increased at 26.4 +/- 8.0 and 28.0 +/- 14.2 day intervals, respectively. However, the fecal contents of progesterone (P(4)) in the female kept alone did not change. In contrast, the other female, which was kept with a male, had increased fecal P(4) contents after copulation. The fecal progesterone levels of the pregnant female remained high during her 106-day pregnancy.     

Heterologous antibodies to evaluate the kinetics of the humoral immune response in dogs experimentally infected with Toxoplasma gondii RH strain

An IgM capture ELISA using heterologous antibodies was developed to evaluate the kinetics of the humoral immune response in dogs experimentally infected with Toxoplasma gondii RH strain. Detection of parasite in tissues from inoculated dogs was evaluated by mouse bioassay and immunohistochemical techniques. Serum samples were obtained at regular intervals up to 62 days post-inoculation (p.i.), when the animals were necropsied and their tissues examined. Antibody levels were measured by IgM capture ELISA (McELISA), indirect hemagglutination (IHA), indirect fluorescent antibody test (IgG-IFAT) and indirect immunoenzymatic assay (IgG-ELISA). All dogs seroconverted but only one exhibited severe clinical signs of infection. IgM antibodies were detected by McELISA from the seventh day on, with decreasing IgM levels around the 27th day. Similar results were obtained from IHA, although McELISA showed earlier and longer detection of IgM antibodies. IgG antibodies were detected from the seventh day on, and throughout the period of observation. Immunohistochemical findings and mouse bioassay revealed the presence of free tachyzoites in tissues of the clinically affected dog only. These results suggest that T. gondii acute infection in dogs shows a remarkably transient IgM synthesis, and this feature may constitute an important marker of active infection. Furthermore, McELISA was shown to be a potential tool to diagnose canine toxoplasmosis.     

Clinical, clinicopathologic, and parasitologic observations of trypanosomiasis in dogs infected with North American Trypanosoma cruzi isolates

Nineteen purebred Beagles of various ages (4, 5, 13, and 47 weeks) were inoculated with North American Trypanosoma cruzi isolates obtained from an opossum (Tc-O), an armadillo (Tc-A), or a dog (Tc-D). Dogs were grouped on the basis of clinical outcome of infection. During the acute stage of disease, dogs of group 1 (n = 7 inoculated with Tc-O or Tc-A) died or were euthanatized because of the severity of disease. Dogs of group 2 (n = 5 inoculated with Tc-O or Tc-A) developed acute disease, but survived to develop chronic disease. Dogs of group 3 (n = 7 Tc-D-inoculated dogs) developed neither acute nor chronic disease. Dogs of group 4 (n = 4--2 dogs 13 weeks old and 2 dogs 47 weeks old) served as noninoculated controls. Clinical signs associated with severe acute myocarditis developed in dogs of groups 1 and 2 between postinoculation day (PID) 15 and 28. Generalized lymphadenopathy and lymphocytosis were observed in all dogs of groups 1, 2, and 3 between PID 14 and 17. Serum alanine transaminase and aspartate transaminase activities and urea nitrogen concentration were high, and glucose concentration was low prior to death of dogs in group 1. Serum activities of isoenzymes of creatine kinase were significantly (P less than 0.05) high in only 1 dog (group 1), whereas serum lactate dehydrogenase isoenzyme activities were not significantly high in any dog.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection by ELISA of the humoral immune response in rabbits naturally infected with Trichophyton mentagrophytes

An indirect enzyme linked immunosorbent assay (ELISA) was developed and its diagnostic potential evaluated for rabbits infected by Trichophyton mentagrophytes. Within-run and between-run coefficient of variance varied from 2.3 to 7.7% and from 5.9 to 8.5%, respectively, indicating satisfactory reproducibility of the ELISA. There was no significant cross-reaction with antigens of Microsporum canis, Malassezia pachydermatis and Aspergillus fumigatus. The level of specific IgG to Trichophyton mentagrophytes was measured in sera of 25 11-week-old and 12 younger infected rabbits. There was no significant difference in the IgG level between 12 5-week-old infected rabbits and controls (p = 0.38). The antibody response was higher in 12 7-week-old rabbits compared with controls (p = 0.001). The IgG level in 25 11-week-old rabbits differed from the controls very significantly (p < 0.0001). Increased specific IgG in 11-week-old rabbits exhibited 96% sensitivity and 94% specificity. Predictive values of a positive and a negative test were 96 and 94%, respectively. Western immunoblotting associated three protein bands (21.5, 31, 44 kDa) with Trichophyton mentagrophytes infection.     

Reactivation of a Trypanosoma cruzi infection in a rhesus monkey (Macaca mulatta) experimentally infected with SIV

Trypanosoma cruzi-like flagellates were incidentally noted in blood smears of a routinely monitored rhesus monkey experimentally infected with the simian immunodeficiency virus (SIV). Immunodeficiency in the course of the SIV infection reactivated a chronic infection of Chagas' disease that had been unnoticed when the macaque was imported to Europe. The animal developed no specific clinical symptoms of American trypanosomiasis, but histologically a chagasic myocarditis was detected. Analysis of the small subunit rRNA gene of the trypanosome identified the protozoan as T. cruzi.     

Blood cellular immune response in pigs immunized and challenged with Haemophilus parasuis

The cellular immune response to an experimental infection by Haemophilus parasuis, the etiological agent of Glässer’s disease in pigs, was characterized studying changes in peripheral blood mononuclear cells (PBMC) in colostrum-deprived pigs. Five groups were studied, four of those were previously immunized with different formulations and the fifth was maintained as non-immunized control. All groups were challenged with 5 × 10⁹ CFU of H. parasuis serotype 5. The non-commercial bacterin conferred a complete protection, while the OMP-vaccine and the exposure to a subletal dose of 10⁵ CFU of H. parasuis protected only partially, and the recombinant Tbp B-vaccine induced no protection. PBMC were analyzed using monoclonal antibodies against porcine CD45⁺, CD3⁺, CD4⁺, CD8α⁺, CD25⁺, CD4⁺ naïve, αIgM⁺ and SWC3⁺ cells in single-colour fluorescence, and CD4⁺/CD8α⁺ and CD8α⁺/CD8β⁺ combinations in two-colour fluorescence. The different groups showed no significant changes in PBMC subsets following vaccination, and only minor changes were encountered after challenge, consisting mainly of significant increases (P < 0.05) in the relative proportions of monocytes and granulocytes (SWC3⁺) and B cells (αIgM⁺), as well as a significant reduction in CD3⁺ cells (P < 0.05). These changes were similar for the five groups compared, except for the significant increase of CD25⁺ cells, which was only observed for the bacterin-vaccinated group. These results suggest an increase of trafficking of inflammatory cells and the onset of the adaptive antibody response against H. parasuis infection; in addition, the blood cellular response developed by the different groups was not relevant to protection.     

Dynamics of the humoral immune response of calves infected and re-infected with Cooperia punctata

The dynamics of the humoral immune response of calves were analysed after primary infection and re-infection with the intestinal nematode Cooperia punctata. 12 male 5 month-old Holstein-Friesian calves were randomly divided into two groups A and B. At the beginning of the experiment Group A animals were each infected experimentally with a single oral dose of 130,000 infective third stage larvae (L3) of C. punctata. The animals of Group B were kept as non-infected controls. The two calves from Group A with the highest infections died of cooperiosis at 32 and 44 days after infection (DAI), respectively. On DAI 100 the calves were treated with the recommended dose of oxfendazole. On DAI 180 the remaining four calves of Group A and three animals of Group B (B1) were infected with 260,000 L3 of C. punctata, while the other three calves of Group B (B2) served as non-infected controls. Monitoring of the humoral immune response predominantly demonstrated an IgG1 response against both adult and L3 antigen of C. punctata. Moreover, re-infections increased the levels of these immunoglobulins. IgA levels were less increased than IgG1 and no significant increase was observed in IgG2 and IgM levels. Immunoblotting analysis showed that total IgG present in the serum of the primary infected animals mainly reacted against adult proteins of 12-14 and 17-20 kDa and against L3 proteins of 33 and 43 kDa. After re-infection total IgG reacted with the same adult proteins but also with an adult 29 kDa protein.     

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19 and in cattle infected with Brucella abortus field strain.

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19, cattle infected with B abortus field strain, and nonexposed cattle were studied by an in vitro lumphocyte-stimulation test (LST). Lymphocytes were prepared from peripheral bovine blood by the Ficoll-diatrizoate technique, and results were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Serotests and bacteriologic isolation attempts were conducted simultaneously with LST. Lymphocytes from cattle infected with field strains had significantly (P = 0.01) higher specific lymphocyte-stimulation inexposed controls. The LST, the serum standard-tube agglutination test (STT), the Rivanol (RIV) test, and the complement-fixation (CF) test correctly classified cattle from which field strains and strain 19 of B abortus were isolated. The LST was negative in cattle vaccinated with B abortus strain 19 (nonshedding), but the three serotests had many false-positive reactions. The CF test had the least false-positive reaction, followed by the RIV test, and the STT was the least specific. Well before the three serotests became positive, the LST was positive in samples from some cattle during the incubation period of the infection. There was little or no correlation between cell-mediated immune responses (as measured by LST) and serum antibody responses (as measured by STT, RIV test, and CF test) in vaccinated but culture-negative cattle and in some nonvaccinated cattle during the incubation period.