Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX

Toye P. G. and Jenkin C. R. 1982. Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX. International Journal for Parasitology12: 399–402. Zymosan and Salmonella enteritidis 11RX were found to partially protect mice against infection with the cestode Mesocestoides corti. Thus, mice previously infected with S. enteritidis 11RX contained fewer parasites in the peritoneal cavity compared to normal mice. Mice pretreated with zymosan contained fewer parasites in the peritoneal cavity and in the liver compared to normal mice and this protection was enhanced by the passive transfer of serum from mice chronically infected with M. corti. Examination of mice in the initial stages of infection revealed that the administration of zymosan led to an alteration in parasite location from the peritoneal cavity to the liver.     

Taenia crassiceps: Immunity to metacestodes in BALB/c and BDF1 mice

The kinetics of primary and secondary infections with Taenia crassiceps larvae and the effects of immune serum on T. crassiceps larvae were studied in BALB/c and BDF1 mice. In both strains of mice a substantial degree of resistance to reinfection comparable to that previously reported in C3H mice can be induced by subcutaneous injection of three larvae 3 weeks prior to intraperitoneal challenge infection. Both early immune damage in the absence of adherent host cells and encapsulation by host cells are involved in rejection of larvae by BALB/c and BDF1 mice, but in both of these strains early immune damage is less pronounced and the cellular encapsulation response considerably more prominent than in the C3H mice studied previously. This difference is also reflected in the effect of immune serum on T. crassiceps metacestodes in vitro: immune serum from BALB/c and BDF1 mice is less effective than immune serum taken from C3H mice at comparable times after challenge infection in mediating damage to T. crassiceps larvae in vitro in the absence of host cells. These results suggest that genetically determined differences in immune capability can alter the state of equilibrium existing among different immune effector mechanisms without producing measurable effects upon overall host resistance to reinfection.     

Kinetics of primary and secondary infections with Taenia crassiceps metacestodes (Zeder, 1800) rudolphi, 1810 (cestoda: cyclophyllidea)

Siebert A. E. Jr., Good A. H. & Simmons J. E. 1978. Kinetics of primary and secondary infections with Taenia crassiceps metacestodes (Zeder, 1800) Rudolphi, 1810 (Cestoda: Cyclophyllidea). International journal for Parasitology8: 39–43. When three T. crassiceps metacestodes were inoculated intraperitoneally in mice as a primary infection, approximately 50% of the larvae recovered during the first 4 weeks after inoculation were found to be dead, while in mice primed by previous subcutaneous inoculation, about 85% of the larvae died. Larvae which survived the first 4 weeks following primary intraperitoneal inoculation reproduced asexually by exogenous budding and produced viable infections within the host mice. But larvae in secondary infections were encapsulated by host granulomata, failed to reproduce asexually, and did not produce viable infections. In mice given intraperitoneal inoculations of seven, ten and twenty metacestodes, fewer larvae were killed and little encapsulation response was noted, though host cells were common at the budding region of the larvae. Such a biphasic host-response to the infection has not previously been reported for larval cestode infections, and the reduction in host response associated with increased worm burdens may indicate possible depression of the host immune system.     

Stimulation of resistance to Taenia taeniaeformis in the rat by infection with Fasciola hepatica

Homologous resistance to F. hepatica and T. taeniaeformis and cross resistance between these two parasites was investigated in the rat. Rats given a primary infection with F. hepatica were challenged with either F. hepatica or T. taeniaeformis. Conversely rats given a primary infection with T. taeniaeformis were challenged with either F. hepatica or T. taeniaeformis.Infection with F. hepatica generated significant resistance against challenge with F. hepatica given 9 weeks later. Similarly, infection with T. taeniaeformis protected against challenge with T. taeniaeformis given 6 weeks later. Infection with F. hepatica also generated significant resistance against challenge with T. taeniaeformis given 4, 8 or 9 weeks later. Primary infection with T. taeniaeformis did not protect against challenge with F. hepatica.     

The stimulation of resistance in sheep to Fasciola hepatica by infection with Cysticercus tenuicollis

Infection of sheep with Cysticerus tenuicollis for 12 weeks generated a high level of protection (> 95%) against intra-ruminal challenge with metacercariae of Fasciola hepatica as measured by recovery of flukes from liver and bile ducts and counts of fluke eggs in faeces. The animals were resistant to Fasciola whether challenge was superimposed upon the cestode infection or after removal of the cestode with mebendazole.Previous infection with C. tenuicollis also protected against the pathogenic effects of challenge infection with F. hepatica. Liver fibrosis was much less extensive in resistant sheep than controls and PCV's were not affected although these were reduced during fluke infection in the control animals.     

Further observations on the nature and characteristics of cross protection against Fasciola hepatica produced in sheep by infection with Cysticercus tenuicollis

Dineen J. K., Kelly J. D. and Campbell N. J. 1978. Further observations on the nature and characteristics of cross protection against Fasciola hepatica produced in sheep by infection with Cysticercus tenuicollis. International Journal for Parasitology8: 173–176. Previous studies showed that sheep infected with Cysticercus tenuicollis were protected against a subsequent infection with Fasciola hepatica given at 12 weeks (Campbell, Kelly. Townsend & Dineen, 1977). The present studies showed that these animals were again protected against re-challenge with F. hepatica at 9 months. Resistance was detected about 10 weeks after re-challenge with metacercariae.Sheep in which the initial C. tenuicollis infections were terminated by anthelmintic at 12 weeks, were resistant to the primary infection with F. hepatica but became fully susceptible to the re-challenge at 9 months.These results suggest that maintenance of resistance depends upon persistence of the C. tenuicollis infections. They also indicate that resistance is maintained by cysts in the peritoneum which is remote from the reactive site (liver).Infection with F. hepatica at 3 weeks after infection with C. tenuicollis prevented cross protection against both the primary infection with F. hepatica and re-challenge at 9 months.     

A comparative study of the susceptibility of inbred strains of mice to infection with Mesocestoides corti

White T. R., Thompson R. C. A. and Penhale W. J. 1982. A comparative study of the susceptibility of inbred strains of mice to infection with Mesocestoides corti. International Journal for Parasitology12: 29–33. The susceptibility of 6 strains of inbred mice to infection with Mesocestoides corti was studied following both intraperitoneal and oral inoculation of tetrathyridia. The greatest degree of resistance was seen in C57BL/6 mice and this resistance was independent of route of inoculation. The proliferation of the parasite in C57BL/6 mice was compared with a more susceptible strain (CBA/H) on 7, 14, 21, 35 and 60 days post-infection. Although both strains harboured significantly different parasite burdens during the initial period following infection, these differences were no longer apparent by day 60.     

Taenia crassiceps: Serum and surface immunoglobulins in metacestode infections of mice

Serum levels of IgM, IgA, IgG1, IgG2a, IgG2b, and IgG3 were measured weekly for 8 weeks by radial immunodiffusion in pooled sera from female BALB/c and BDF1 mice with primary and secondary Taenia crassiceps infections and age-matched normal control mice of each strain. Although increases in levels of all immunoglobulin classes occurred during primary and secondary infections in both strains of mice, the only consistent changes common to both strains of mice were higher levels of IgG1 and IgG3 in early weeks of secondary infections as compared to primary infections, and high levels of IgG1 late in primary infections. High levels of IgG3 occurred late in primary infections in BDF1 mice but not in BALB/c mice. It was not possible to correlate increased levels of any one immunoglobulin class either with cytotoxic activity of early immune serum or with the onset of the cellular encapsulation response in secondary infections. IgM, IgA, IgG1, IgG2a, IgG2b, and IgG3 could be demonstrated on the surface of washed fixed larvae from long-term infected donor mice by the indirect fluorescent antibody method. Living T. crassiceps larvae were capable of shedding fluorescent label within 1 hr at room temperature, but not at 4 C after staining with either rabbit anti-T. crassiceps serum or rabbit anti-mouse immunoglobulin serum and fluorescein-conjugated goat anti-rabbit globulin.     

Some effects of time,temperature and feeding on infection rates with Babesia bovis and Babesia bigemina in Boophilus microplus larvae

Dalgliesh R. J. and Stewart N. P. 1982. Some effects of time, temperature and feeding on infection rates with Babesia bovis and Babesia bigemina in Boophilus microplus larvae. International Journal for Parasitology12: 323–326. Percentages of larval ticks in which Babesia bovis and B. bigemina parasites could be detected (infection rates) were determined after the larvae had been exposed to temperatures between 9°C and 27°C for periods of 1–35 days and then either fed on calves or heated at 37°C to stimulate babesial development. Infection rates with both species increased during 2–4 weeks after the larvae hatched, regardless of the temperature of exposure. Infection rates with B. bovis were higher after exposure of larvae to 14°C than to 27°C. This effect was less pronounced with B. bigemina. Infection rates were higher in fed larvae than in unfed, ‘heat stimulated’ larvae. The findings indicate that infected larval ticks become more efficient vectors of Babesia during the first 2–4 weeks after hatching and that repeated sampling of a tick population is necessary to determine valid infection rates.     

Spontaneous sexual differentiation of Mesocestoides corti tetrathyridia in vitro

Barrett N. J., Smyth J. D. and Ong S. J. 1982. Spontaneous sexual differentiation of Mesocestoides corti tetrathyridia in vitro. International Journal for Parasitology12: 315–322. Tetrathyridia of Mesocestoides corti, from the body cavity of mice, maintained in the laboratory by intraperitoneal infection, were used for in vitro culture. In an initial experiment, after 50 days asexual multiplication in vitro one tetrathyridium spontaneously segmented and developed into a sexually mature adult. Further experiments were carried out in an attempt to determine the conditions favouring segmentation and sexual differentiation. A combination of 5 or 10 ml liquid medium S1OE.H (basically composed of CMRL 1066 and foetal calf serum with supplements) changed every 3 days, in a Leighton tube (19 × 105 mm), rotated at 38°C and gassed with 10 or 20% CO₂, containing between 100 and 200 tetrathyridia, has proved to be most suitable so far. Numerous adult worms with normal male and female genitalia have been obtained in this system. However, segmentation is sporadic, rather than consistent and only a few shelled eggs with hooked oncospheres have so far been obtained, suggesting that impregnation and fertilization in vitro is not fully comparable with that in vivo.     

Comparison of rapid expulsion of Trichinella spiralis in mice and rats

Alizadeh H. and Wakelin D. 1982. Comparison of rapid expulsion of Trichinella spiralis in mice and rats. International Journal for Parasitology12: 65–73. Primary infections of Tricliinella spiralis in both NIH mice and Wistar rats resulted in increased levels of mucosal mast cells and goblet cells. In mice the numbers of both cell types rose sharply before worm expulsion (days 8–10), remained at an increased level for a short time and declined quickly, reaching control levels on day 14 for goblet cells and between days 28 and 35 for mast cells. In contrast, in rats, the numbers of goblet cells and mast cells increased during worm expulsion and remained above control levels for a prolonged period. Challenge infections given shortly after expulsion of a primary infection (day 14) were expelled rapidly, worm loss being virtually complete with 24 h. In mice this response to challenge was short-lived and persisted only until day 16 after primary infection. After this time, challenge worms were expelled more slowly after infection. In rats the rapid expulsion response was expressed for at least 7 weeks after primary infection. Mice and rats showed differences in the conditions of infection necessary to prime for rapid expulsion, mice requiring larger and longer duration primary infections, but the expression of the response appeared to be similar in both species. In mice it was shown that rapid expulsion of T. spiralis was a response evoked specifically by prior infection with this species; infections with other intestinal nematodes had no effect. Similarly, the effect upon challenge infection was also specific to T. spiralis. The rapidity with which challenge infections are expelled suggests that either the specific inflammatory changes generated during primary infection result in an environment that is unsuitable for establishment of subsequent infections or that challenge infections provide a stimulus that can provoke an almost instantaneous response in the primed intestine. The relationship of the observed cellular changes to such mechanisms is discussed.     

Effects of mebendazole and levamisole on tetrathyridia of Mesocestoides corti in the mouse

Bennet E.-M., Behm C.A. and Bryant C. 1978. Effects of mebendazole and levamisole on tetrathyridia of Mesocestoides corti in the mouse. International Journal for Parasitology8: 463–466. Mebendazole, but not levamisole, administered to mice carrying artificial infections of 50 tetrathyridia of Mesocestoides corti, was effective in killing the parasites. However, simultaneous administration of mebendazole and levamisole was still more effective. Treatment with levamisole before infection had no additional effect.Injection of mice with dead larvae offered some protection against a subsequent challenge with 50 live larvae; however, levamisole did not then improve the anthelmintic efficacy of mebendazole. In mice rendered immunoincompetent by radiation mebendazole was less effective than in non-irradiated controls and levamisole again did not enhance the effect of mebendazole. It is concluded that anthelmintic efficacy of mebendazole depends on its anthelmintic activity supplemented by the host's immune response; and that levamisole stimulates the latter.     

Schistosoma mansoni and Fasciola hepatica: Cross-resistance in mice

Cross-resistance in Schistosoma mansoni and Fasciola hepatica infections were studied in mice. A primary infection of S. mansoni, 7 to 28 days old, did not stimulate a significant level of resistance to heterologous challenge with F. hepatica. In contrast, in older S. mansoni infections (54–65 days old) there was a significant level of resistance to a challenge with F. hepatica. The F. hepatica worm burden was reduced by 34.0 to 72.5% in separate experiments. Challenge infection with F. hepatica did not influence the number of S. mansoni in primary infections. No heterologous resistance to S. mansoni was found in mice with 7- and 23-day-old F. hepatica infections. However, primary infections with F. hepatica, 28, 32, 42, and 50 days old, conferred significant resistance to a heterologous challenge with S. mansoni. The established schistosome worm burden was reduced by 41.5 to 50.4%. In no case was the primary F. hepatica burden reciprocally influenced by challenge infection with S. mansoni.     

In vitro development of the strobilar stage of Mesocestoides corti

Thompson R. C. A., Jue Sue L. P. and Buckley S. J. 1982. In vitro development of the strobilar stage of Mesocestoides corti. International Journal for Parasitology12: 303–314. Sexually mature strobilated adults of Mesocestoides corti were grown consistently from undifferentiated tetrathyridia in vitro using a conventional diphasic culture system. Development (growth, strobilisation and maturation) was compared in vitro and in vivo. Although growth and strobilisation were comparable in vitro and in vivo, during the first 18 days, total length and numbers of proglottids decreased in vivo but continued to increase in vitro after day 18. Both male and female reproductive systems appeared to develop normally in vitro and self copulation was frequently observed in cultured worms. However, fully developed oncospheres were not produced in vitro.     

The response of lambs to vaccination and challenge with Trichostrongylus colubriformis: Effect of plane of nutrition on,and the inter-relationship between,immunological responsiveness and resistance

Wagland B. M., Steel J. W., Windon R. G. and Dineen J. K. 1984. The response of lambs to vaccination and challenge with Trichostrongylus colubriformis: effect of plane of nutrition on, and the inter-relationship between, immunological responsiveness and resistance. International Journal for Parasitology14: 39–44. Merino lambs weaned at 8 weeks of age were fed either ground and pelleted (high plane, HP) or chopped (low plane, LP) lucerne hay ad libitum to achieve an approximate 2-fold difference in liveweight gain. When aged 17 and 21 weeks, 15 of the 20 lambs in each diet group were vaccinated with 80,000 irradiated T. colubriformis larvae. At 25 weeks, vaccinated and unvaccinated lambs were treated with anthelmintic and one week later challenged with 30,000 normal larvae. Four weeks after challenge the animals were killed for worm counts. After vaccination HP lambs had higher titres of antibodies to the parasite and after challenge had lower worm egg outputs, and lower worm burdens than LP lambs. Immunological responsiveness (serum titre of complement-fixing antibodies against worm antigen) and manifestations of resistance (eggs produced per female worm per day and percent protection calculated from worm counts) were significantly correlated within dietary groups. Percent protection and egg production per female worm were highly correlated (r = ?0.81) in individual animals pooled over dietary groups, suggesting that both manifestations of resistance respond to essentially the same immunological mechanism. Failure to obtain significant correlation between weight gain pre-vaccination and immunological and resistance parameters indicated that animal production and resistance to infection are not genetically linked. Negative correlation of weight gain during the vaccination period with serum antibody titre at challenge suggests that the developing immune response competes with weight gain for limited physiological resources of the animal.     

The response of sheep to parenteral vaccination and immunizing infections against the abomasal nematode, Haemonchus contortus

Adams D. B., Beh K. J. and Davies H. I. 1982. The response of sheep to parenteral vaccination and immunizing infections against the abomasal nematode, Haemonchus contortus. International Journal for Parasitology12: 445–449. Subcutaneous injection of relatively large amounts of unfractionated homogenates of adults plus infective larvae of Haemonchus contortus emulsified in complete Freund's adjuvant produced a degree of protective immunity when challenge infection was given eight weeks after the first or only dose of vaccine. In an attempt to improve acquired immunity, parenteral vaccination was either followed or preceded by a short immunizing infection with H. contortus, which was terminated by anthelmintic before patency. This treatment aimed at stimulating general responsiveness to worm antigens and invoking mucosal immunity in the abomasum. Disparate results were obtained; immunizing infections either increased immunity or made sheep more susceptible to challenge infection. In this latter situation, the unresponsiveness associated with primary infection with H. contortus may have been increased.     

Leishmania mexicana and Leishmania tropica: Cross immunity in C57BL/6 mice

Leishmania mexicana and Leishmania tropica infection were comparatively studied in C57BL/6 mice. Infection with 10⁴ amastigotes of L. mexicana was followed by the appearance of a single lesion which ulcerated in 8 weeks and healed in 24 weeks. Mice infected with 10⁴ amastigotes of L. tropica developed less severe lesions which healed in 18 weeks. In both cases healing was accompanied by a delayed hypersensitivity response and an in vitro lymphocyte reactivity to leishmanial antigens. Mice recovered from a primary infection with L. mexicana or L. tropica were resistant to both homologous and heterologous challenge. In vitro and in vivo immunological tests indicated that L. mexicana and L. tropica share antigenic determinants which are involved in cell-mediated immune responses to these parasites.     

Kinetics of primary and secondary infections with Strongyloides ratti in mice

Dawkins H. J. S. and Grove D. I. 1981 Kinetics of primary and secondary infections with Strongyloides ratti in mice. International journal for Parasitology11: 89–96. The kinetics of infection with S. ratti were quantitated in normal and previously exposed C57B1 /6 mice. In primary infections, larvae penetrated the skin rapidly and were seen in peak numbers 12 h after infection. By 24 h after infection, larval numbers had declined appreciably and there was a slow decrease in numbers thereafter. Larvae were first observed in the lungs at 24 h and maximal recovery occurred at 48 h. It is thought that larval migration through the lungs is rapid. Worms were first seen in the intestines two days after infection. Maximum numbers were seen on the fifth day and worm expulsion was complete by day 10. Two moults took place in the small intestine during days 3 and 4 after infection. Rhabditiform larvae were first noted on the fourth day after infection. Mice exposed to S. ratti four weeks previously had significantly less larvae in the skin 4 and 12 h after infection but by 24 h there was no difference when compared with mice with primary infections. Peak recovery of larvae from the lungs occurred 24 h after infection; significantly less larvae were recovered on days 2 and 3 when compared with normal mice. There was a marked reduction in the adult worm burden in the gut; the number of worms recovered was less than one fifth of that seen in primary infections. Those worms which did mature were less fecund and were expelled from the intestines within 7 days of infection. It is suggested that in previously exposed animals, the migration of larvae from the skin is hastened, many of these larvae are destroyed in the lungs and that expulsion of worms which do mature in the intestines is accelerated.     

Histopathological changes in livers of mice infected with tetrathyridia of Mesocestoides corti and exposed to different environmental temperatures

Novak M. 1982. Histopathological changes in livers of mice infected with tetrathyridia of Mesocestoides corti and exposed to different environmental temperatures. International Journal for Parasitology12: 41–45. Observations on the histopathology of the liver of mice infected with Mesocestoides corti and kept for 20 days p.i. (post-infection) at low (5 ± 1°C), room (21 ± 1°C) or high (35 ± 1°C) temperature revealed that the degree of liver pathology was directly proportional to the intensity of liver infection, which in turn was the result of the temperature effect. The most severe pathological changes occured in the heavily infected organs of mice kept at low temperature, followed by less prominent changes in moderately infected livers of mice kept at room temperature and the smallest changes in lightly infected livers of mice kept at high temperature. The pathological changes in infected and uninfected livers of hosts exposed to different environmental temperatures are described and compared.     

Isolation of Fasciola hepatica genus-specific antigens

Santiago de Weil N., Hillyer G. V. and Pacheco E. 1984. Isolation of Fasciola hepatica genus-specific antigens. International Journal for Parasitology14: 197–206. The Fasciola hepatica antigens which induce antibody formation in acute fascioliasis were isolated by acid elution after reacting an F. hepatica tegument antigen extract with a CNBr-Sepharose 4B column coupled with IgG obtained from the serum of rabbits infected with fascioliasis for 6–10 weeks. These isolated antigens were further separated by gel filtration using a column packed with Sephacryl S-200. In this manner three major peaks were obtained. The best serologic antigens were found in peak 2 which had a mol. wt range of 14,000–43,000. This peak contains genus-specific F. hepatica antigens which are highly reactive with fascioliasis serum. These antigens do not cross-react with either Schistosoma mansoni or with bovine serum albumin by gel diffusion. Monitoring by ELISA and gel diffusion with heterologous and homologous antisera showed that as purification by antibody affinity chromatography proceeded, cross reactivity with S. mansoni was eliminated. The rabbit antiserum obtained against peak 2, when tested by immunoelectrophoresis with a crude F. hepatica extract shows one main band identical to the main band observed with serum from acutely infected rabbits. Up to two other minor bands can be detected using concentrated homologous antisera. Fractions obtained from preparative iso-electric focusing of the F. hepatica tegument extract were reacted with sera from rabbits with acute fascioliasis. Two main bands were observed in immunodiffusion with antigens eluting in a pH range of 7.4–8.7. When these fractions were monitored with anti peak 2 antisera, two precipitin bands appeared with antigens eluting in a pH range of 7.4–7.9. The F. hepatica genus-specific antigen pool was applied to ELISA to evaluate its ability to detect antibody in a primary F. hepatica infection in rabbits. A rise in absorbance values could be detected by 2 weeks of infection, reached high levels by 6 weeks and remained high through 28 weeks of infection.