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Biomedical subjects

R J Terry

Publications and source records attributed to R J Terry.

At least 19 recordsLinked to original sources
PubMed1989

The choice of adjuvants in Mycoplasma vaccines.

The use of adjuvants in vaccine production is an important aspect of potent vaccines. This investigation was concerned with finding the most efficient adjuvants for use in Mycoplasma vaccines produced in Nigeria. Four different vaccines were produced from the Gladysdale strain of Mycoplasma mycoides subspecies mycoides. They differed depending on the type of adjuvants used. Each vaccine was used to vaccinate eight cattle using a dose of 1 ml. Two other groups of eight cattle were used as controls. One of the two groups received 1 ml dose of inactivated Gladysdale vaccine without adjuvant while the second group received 1 ml dose of saline. The number of cattle that had the peak complement fixing (CF) antibody titres of 1/80 in each group of cattle was four for vaccine containing aluminium hydroxide gel, eight for vaccine containing liquid paraffin, one for vaccine containing sodium alginate and one for vaccine without adjuvant. Seven cattle from the group vaccinated with vaccine containing Freund's incomplete adjuvant had peak CF antibody titres of 1/80 or higher. The two groups vaccinated with vaccine containing liquid paraffin and Freund's incomplete adjuvant survived challenge at 6 months post vaccination. Freund's incomplete adjuvant and liquid paraffin containing 10% Arlacel A are the most efficient adjuvants.

Adjuvants, Immunologic↗
PubMed1987

Macrophage procoagulant activity in experimental African trypanosomiasis.

Peritoneal macrophages from mice infected with Trypanosoma brucei brucei expressed a greatly elevated procoagulant activity (PCA) which could be reversed to normal levels after trypanocidal therapy. Comparison with infection caused by the non-pathogenic T. musculi suggested that the level of PCA related to parasite pathogenicity. Unstimulated macrophages, which generate only slight PCA upon stimulation with zymosan, become hyperresponsive to this stimulus during the course of infection. Hyperresponsiveness is not a generalized feature of these cells during infection, as they become progressively hyporesponsive to the same stimulus in terms of lysosomal enzyme secretion. We were unable to demonstrate a direct role of the trypanosomes in macrophage activation; however, artificial removal of the glycoprotein coat rendered the parasites highly stimulatory for macrophages even in the absence of opsonins. These results suggest that the parasites may activate macrophages indirectly, and that the resulting elevated PCA may play a role in the abnormal blood coagulation known to occur in this disease.

Animals↗
PubMed1987

T-lymphocyte requirement for the induction of mouse macrophage procoagulant activity by Trypanosoma brucei.

We have previously shown that peritoneal macrophages from Trypanosoma brucei infected mice, but not from uninfected mice, expressed high levels of procoagulant activity that could not be produced in vitro by incubation of unstimulated macrophages with bloodstream forms of trypanosomes. In the present study we demonstrate that trypanosome-induced macrophage activation can be achieved in vitro by providing either sensitized (day 7 of infection) lymphocytes and trypanosomes or the supernatant fluid from this interaction. The ability of lymphocytes to secrete macrophage-activating lymphokines is enhanced up to day 12 of infection but was absent in the later stages. Although enhancement of the procoagulant activity occurred in infected nude mice, it seems that macrophage function in African trypanosomiasis, as regards the expression of procoagulant activity, is regulated by T-lymphocytes.

Animals↗
PubMed1986

Immunogenicity of oil-based contagious bovine pleuropneumonia vaccine in cattle.

The effects on the immunity in cattle of dosage and storage of oil-based inactivated vaccine incorporating the Gladysdale strain were examined. Storage at 4 degrees C for 12 or 24 months was found not to have any marked effect on the immunity conferred in the vaccinated cattle. A dosage of 0.5 ml was found to be as effective as dosages at 1 and 2 ml of the inactivated vaccine. To assess the potency of the inactivated vaccine in cattle two methods were used: antibody response to the vaccine using the complement fixation test and the challenge test in cattle by contact using a virulent strain at 2 and 6 months after vaccination.

Animals↗
PubMed1986

Cellular mechanisms involved in recovery from acute malaria in Gambian children.

This paper reports the results of in vitro experiments which attempt to elucidate the mechanisms whereby Gambian children control acute infections of Plasmodium falciparum. It was shown initially that mononuclear cells from children with acute malaria, in the presence of specific antibody, caused a marked reduction in in vitro parasite growth. IgM antibodies appeared to be considerably more effective than IgG. T or B lymphocytes were ineffective in the system; adherent cells alone had some effect, but much less than the unfractionated cell population. Adherent cells were however fully effective after exposure to supernatants from T cells activated either non-specifically by phytohaemagglutinin (PHA), or specifically by P. falciparum antigens. Depression of parasite growth was also observed, independent of anti-malarial antibody. This was achieved when adherent cells from healthy Europeans, as well as those from infected children, were exposed to the supernatants from previously stimulated T cells before adding to the culture. Furthermore, intra-erythrocytic parasite death occurred after a short exposure to the supernatants of 'activated' adherent cells from both infected children and Europeans.

Adolescent↗
PubMed1982

The protective role of acquired host antigens during schistosome maturation.

Schistosomes grown in mice were tested at different stages of development for susceptibility to an in vitro cytotoxic effector mechanism involving eosinophils and an antibody directed against mouse determinants. Despite the fact that 5-day lung worms and 6-week adult worms both bound the antibody to their surfaces, eosinophils attached preferentially to the adults and killed them. Complement had an enhancing effect in this system. Those eosinophils which did adhere to the lung worms degranulated onto the tegument but were unable to mediate damage or killing, even when complement was activated at the parasite surface. The resistance shown by the lung worms was shared by 2-week worms and small 3-week worms. Larger 3-week worms and older stages were, however, susceptible to cell-mediated cytotoxicity in this system. We suggest that the host antigen disguise constitutes the major protective mechanism utilized by older schistosomes to evade immunity, but that the younger stages have an additional and equally effective mechanism of resistance.

Animals↗
PubMed1982

Phytohaemagglutinin reactivity in circulating peripheral blood lymphocytes during a Trypanosoma brucei infection: sequential studies in individual guinea-pigs.

This study has analysed the response to phytohaemagglutinin of peripheral blood lymphocytes from guinea-pigs infected with Trypanosoma brucei brucei. By this means it was possible to follow the response of individual animals throughout an infection. A culture method using whole blood permitted fewer cell manipulations and eliminated the necessity to supplement cultures with heterologous serum. Selection of appropriate strains of T.b. brucei produced a relatively chronic infection in guinea-pigs. Results from this system indicate that, even late in the disease, significant mitogen reactivity still remains in some individuals. More significantly, these mitogen 'responders' controlled successive parasitaemic waves producing a fluctuating parasitaemia whereas the animals showing poor mitogen responsiveness--'non-responders' failed to control successive waves and showed plateau parasitaemias.

Animals↗
PubMed1981

Bacterial coryza in turkeys in Texas.

A motile, gram-negative, short bacillus was isolated from the tracheas of turkey poults with coryza. An Escherichia coli also was isolated from the tracheas of poults. The former bacterium possessed characteristics similar or identical to those isolated from coryza outbreaks in other states. The characteristics were similar to those described for Alcaligenes fecalis. Cultures of the turkey coryza isolate produced coryza when inoculated intranasally in 1 to 3-day-old poults. The bacterium was reisolated consistently from the tracheas of the affected poults. In one experiment, poults inoculated with the coryza bacterium and the E. coli isolate had an apparent increased incidence of air sacculitis. No viruses were isolated from the tracheas of coryza-affected poults. Blood serums were negative for precipitating and hemagglutination-inhibition antibodies to avian influenza and Newcastle disease viruses, respectively. The serum neutralizing antibody titers to infectious bursal disease virus in noninoculated poults, and poults inoculated with the coryza bacterium, or E. coli or both, were undetectable or low. Serum agglutination was not a reliable method for determining infection by the coryza bacterium.

Alcaligenes↗
PubMed1981

The potentiation effect of citric acid in aureomycin in turkeys.

Citric acid was used to potentiate Aureomycin by administering both materials through the drinking water of turkeys. Treatment groups receiving citric acid consistently had higher blood levels of Aureomycin than corresponding treatments receiving Aureomycin alone. Highly significant differences in tetracycline blood levels were obtained at 24 hr in one experiment and at 48 hr in a second experiment favoring citric acid treated birds.

Administration, Oral↗
PubMed1979

Immunodepression and the course of infection of a chronic Trypanosoma brucei infection in mice.

The relationships between course of infection, antigenic variation, and immunodepression of antibody responses to heterologous antigens have been investigated in mice chronically infected with Trypanosoma brucei. T. brucei Brunel University Trypanosomiasis (BUT) 64 produces a fluctuating parasitaemia lasting about 80 days and ending fatally. It is demonstrated that recurring peaks of parasitaemia are associated with the appearance of new variant antigenic types. At 21 and 31 days of infection, IgG responses to the heterologous antigen, sheep red blood cells (SRBC), are absent and IgM responses are less than 5% of normal. When a single dose of cyclophosphamide (300 mg/Kg) was injected into mice on day 31 of infection, the parasitaemia rose sharply in an uncontrolled fashion and the treated mice died in about 10 days. Cyclophosphamide, given in this way, is known to ablate antibody production completely but temporarily. It is therefore concluded that even though infected mice make extremely poor antibody responses to heterologous antigens, they are still capable of producing sufficient antibody to control peaks of parasitaemia associated with the emergence of new variant antigenic types. The significance of these findings is discussed in relation to recurrent hypotheses of trypanosome-associated immunodepression.

Animals↗
PubMed1977

Anaemia in trypanosomiasis: mechanisms of erythrocyte destruction in mice infected with Trypanosoma congolense or T. brucei.

Studies in mice infected with T. brucei or T. congolense showed that increased red cell destruction in the spleen occurred as from the third day of patent parasitaemia and this resulted in a marked reduction of the half-life of transfused syngeneic 51Cr labelled cells. There was a progressive increase in the osmotic fragility of the red cells, especially in T. congolense infected mice which also showed a more severe anaemia. The antiglobulin test was only rarely positive in the late stages of T. brucei infection. Incubation of normal red cells with plasma from infected mice in vitro did not result in haemolysis, but in the case of plasma from T. brucei infected mice, it caused an appreciable reduction in the half-life of the cells when transfused into normal mice. It is suggested that mechanisms of red cell destruction in trypanosome infections are complex and may vary with the species of trypanosomes, the host and the stage of infection.

Anemia↗
PubMed1976

Acquired resistance to Schistosoma haematobium in the baboon (Papio anubis) after cercarial exposure and adult worm transplantation.

Observations were made on the development of acquired resistance to Schistosoma haematobium in the baboon following immunization with cercariae by the percutaneous route and by the transplantation of adult worms into the mesenteric veins. In the first experiment six baboons were immunized with 1000 S. haematobium cercariae given percutaneously. They were challenged with 10 000 cercariae given 73 weeks later and the results were compared with a similar infection in non-immunized animals. The results showed that the baboon can develop a strong resistance to reinfection with S. haematobium. The manifestations of the immunity were (i) the absence of any increase in egg output after challenge (ii) the substantially lower level of adult worms and eggs in the tissues of the immunized baboons compared with the challenge control animals (iii) a reduction in the egg laying capacity of the residual worms and (iv) the virtual absence of gross pathology and the mild lesions seen in the tissue sections of all the immunized animals. The depression in egg laying of the worms was confirmed by transplanting them into non-immune baboons. This experiment indicated that the non-egg-laying worms in the immune baboons were not irreversibly damaged since they survived, some even migrating to the vesical and ureteric vessels, and egg-laying was rapidly resumed after transplantation. A further experiment was designed to see if a similar degree of immunity could be produced by an adult worm infection without previous exposure to cercariae or schistosomula. The immunization dose consisted of 50-100 S. haematobium worm pairs which were transplanted into the mesenteric veins of each of six baboons and the animals were challenged percutaneously with 7000 cercariae 35-55 weeks later. There was little difference in the worm burdens of the immunized and control animals but the worms in the immunized baboons produced fewer eggs and the pathology seen in these animals was much milder than in the challenge control animals suggesting that some degree of resistance to reinfection was produced by the transplanted worms.

Animals↗
PubMed1976

Acquisition of human blood group antigens by Schistosoma mansoni.

Juvenile forms of Schistosoma mansoni (schistosomula) have been cultured in human blood of various specificities and tested for the presence of blood group substances on their surfaces. The tests employed were survival following transfer into rhesus monkeys immunized against human blood substances, mixed agglutination reactions, and immunofluorescence. A, B, H AND Lewisb+ antigens were expressed at the surface when the parasites were cultured in blood of appropriate specificities. Rhesus, M N S, AND Duffy antigens could not be detected on the parasite surface following culture. The evidence suggests that the expressed blood group antigens are of host origin and are acquired by the parasite during culture, probably in the form of glycolipids or megaloglycolipids. It is likely that these substances are also acquired by parasites in the bloodstream of man. They may serve to mask surface parasite antigens, and so enable schistosomes to evade parasite-specific humoral or cellular immune responses.

ABO Blood-Group System↗