Immunosuppressive activity in serum from mice infected with Nematospiroides dubius following passive serum transfer

Dobson C. and Cayzer C. J. R. 1982. Immunosuppressive activity in serum from mice infected with Nematospiroides dubius following passive serum transfer. International Journal for Parasitology12: 561–566. Anti-N. dubius antibody titres increased with time after primary and secondary infections with 100 larvae in mice and 4 days after anthelmintic termination of a 28 day infection. Mice injected with serum from infected mice harboured fewer, smaller worms with reduced fecundities compared with control mice; the difference was greater with serum from donors given two compared with those given one infection.Mice injected with serum from donors infected for 14 days had fewer N. dubius than recipients of serum from mice infected for 28 days. Serum taken from mice 4 days after termination of a primary infection of 28 days duration was more protective when passively transferred to mice than serum from mice infected for 28 days. Serum from mice infected with 50 N. dubius larvae was more protective than serum, with a higher anti-N. dubius antibody titre, from, mice infected with 400 larvae. These observations are discussed in relation to immunosuppressive activities in the donated serum and associated with N. dubius.     

Observations on the morphology and infectivity for cattle of Babesia bovis parasites in unfed Boophilus microplus larvae after incubation at various temperatures

Dalgliesh R. J. and Stewart N. P. 1979. Observations on the morphology and infectivity for cattle of Babesia bovis parasites in unfed Boophilus microplus larvae after incubation at various temperatures. International Journal for Parasitology9: 115–120. The temperature of incubation of unfed Boophilus microplus larvae infected with Babesia bovis influenced the morphology and infectivity of the Babesia within the tick. Incubation at 37°C for 1–3 days stimulated the development of parasites morphologically similar to those usually observed in fed larvae harvested from cattle; similar forms appeared more slowly in larvae incubated at 31°C or 25°C. Extracts prepared from larvae after incubation at 37°C for 3–5 days or 30°C for 8 days were consistently infective for cattle. Prior storage of larvae at 14°C for up to 28 days enhanced the development of infectivity at 37°C; infectivity could still be produced after 65 days storage at 14°C but not after 76 days. Larvae released on a host transmitted B. bovis sooner if they had been incubated at 37°C for 4 days. It was concluded that the development of B. bovis to an infective stage in B. microplus is temperature dependent and does not require the stimulus of feeding by the host.     

Effect of host sex on passive immunity in mice infected with Nematospiroides dubius

Dobson C. & Owen M. E. 1978. Effect of host sex on passive immunity in mice infected with Nematospiroides dubius. International Journal for Parasitology8: 359–364. Female C₃H but not Quackenbush (Q) mice harboured fewer Nematospiroides dubius than male C₃H and Q mice. Both strains lost worms 21 days after infection. C₃H and Q mice became progressively immune to infection following 4 sequential doses of N. dubius larvae and showed a sex resistance to infection. Hypothymic nu/nu CBA Balb/c mice did not show these effects on N. dubius infection. The reciprocal transfer of male and female immune mesenteric lymph node cells (IMLNC) to syngeneic male and female recipients showed that the female environment enhanced the protective qualities of both male and female IMLNC but the male environment suppressed these effects. Gonadectomized male and female recipients of male and female IMLNC had levels of infection similar to the entire female recipients. Serum from immune female donor mice protected both male and female recipients better than immune serum from male donors, but female mice in each treatment group were better protected than male mice. Immune serum transferred greater levels of protection then IMLNC to recipient mice against N. dubius infections. These data are consistent with the conclusion that the male environment suppresses lymphocyte activity and the production of protective antibodies and additionally may depress the effectiveness of sensitized lymphocytes and antibodies in ejecting N. dubius. On the other hand the female environment does not appear to adversely affect the mobilization of the protective immune response and may enhance immune effector mechanisms in protecting mice against N. dubius infections.     

Alternative pathway activation of complement by a murine parasitic nematode (Nematospiroides dubius)

The cuticular surface of the infectious third-stage larvae of Nematospiroides dubius activates complement via the alternative pathway. Sensitisation of larvae with complement or with antibodies from the serum of immune mice (resistant to reinfection) promoted the adherence of mouse peritoneal exudate cells to the larval cuticle during incubation in vitro. The infectivity of larvae sensitized with antibody or complement was significantly reduced after incubation with cells from immune mice.     

Influence of serial passage on the infectivity and immunogenicity of Nematospiroides dubius in mice

Dobson C. and Owen M. E. 1977. Influence of serial passage on the infectivity and immunogenicity of Nematospiroides dubius in mice. International Journal for Parasitology7: 463–466. The infectivity of Nematospiroides dubius was increased for Quackenbush (Q) mice by ten serial passages through this host. At the same time C(In3)H mice became more refractory to infection with successive Q generations of the parasite. Both strains of mice rejected the most highly selected parasites more readily than parasites from the earlier generations. These responses were shown to be immunological in nature by infections in hypothymic Balb/c CBA nu/nu and nu/+ mice and to be dose dependent. The selection of N. dubius for increased infectivity in Q mice enhanced its immunogenicity in this and other mouse strains possibly because of increased genetic homogenicity in the selected populations. N. dubius selected for Q mice showed a degree of immunologieal adaptation to Q but not to C₃H mice.     

Influence of serum donor and recipient mouse genotype on the passive transfer of protective immunity with serum against Nematospiroides dubius

Dobson C., Brindley P. J. and Sitepu P. 1982. Influence of serum donor and recipient mouse genotype on the passive transfer of protective immunity with serum against Nematospiroides dubius. International Journal for Parasitology12: 567–572. Different strains of serum donor mice showed variations in innate immunity to primary infections with Nematospiroides dubius. Different levels of anti-N, dubius antibodies were detected in sera from these mouse strains; there was no correlation between antibody titre and numbers of worms recovered. Serum from donor wild and six laboratory strains of mice protected female Quackenbush (Q) recipients against N. dubius infections; donor mouse strain influenced the degree of protection conferred and donor serum antibody titre related to the degree of stunting of worm growth in recipient mice. Five laboratory strains of mice developed different levels of protective immunity following multiple experimental infections with N. dubius. Antibody titres in these mice were strongly correlated with the percentage protection observed after 1–4 infections: Q and CBA mice produced more anti-N. dubius antibody and were better protected than DBA/2, BALB/c and C3H mice. However BALB/c, C3H and CBA mice attained similar anti-N. dubius antibody titres after a single infection with N. dubius but serum from BALB/c gave better protection when transferred to female Q recipients than that from the other two strains. This suggested qualitative differences in the protective antibodies in sera between mouse strains. Five mouse strains were passively immunized with a uniform dose of serum from female Q donors: DBA/2 female recipients showed the least, BALB/c and C3H females were intermediate, and Q and CBA female mice attained the greatest level of passive protection against N. dubius. A close positive correlation existed between the degree of actively acquired and the level of passively acquired protection between the five strains of mice.     

Influence of primary infection on the population dynamics of Nematospiroides dubius after challenge infections in mice

Dobson C., Sitepu P. and Brindley P. J. 1985. Influence of primary infection on the population dynamics of Nematospiroides dubius after challenge infections in mice. International Journal for Parasitology15: 353–359. Similar proportions of the inoculum of Nematospiroides dubius larvae reached sexual maturity by 14 days after administration of 50–400 larvae but more adult worms had been expelled by day 63 after infection from those mice infected with 50 vs 400 larvae. There was a significant correlation between time and worm expulsion for all inoculum size groups except for mice given 400 larvae.In mice reinfected with 100 larvae, after termination of primary infections derived from 10 through 400 larvae, more worms from the challenging dose were recovered from mice given greater compared with those given smaller numbers of larvae at primary infection. The N. dubius population size after challenge infection was correlated positively both with number of larvae administered as the primary infection and with the resultant population size during that infection. The serum anti-N. dubius antibody titres after reinfection were higher in mice given 400 compared with those given fewer larvae at primary infection, and the fecundity and female to male sex ratio of the N. dubius populations decreased in proportion to these antibody titres.Protective immunity against challenge N. dubius infection, in mice which had been drenched free of adult worms established from 400 larvae for 5 down to 1 weeks before reinfection, increased from 45% (1 week) to 80% (5 weeks). There was a negative correlation between the population size of N. dubius during challenge infection and the duration between anthelmintic treatment and challenge infection.     

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.     

Taenia crassiceps: effect of normal and immune serum on metacestodes in vitro.

The effect of normal and immune serum on Taenia crassiceps larvae in vitro was assessed by Evans blue dye uptake and electron microscopy. Normal guinea pig, rabbit, goat, and fetal calf serum did not have any significant detrimental effects upon the larvae after 7 days of culture in vitro. Culture for 7 days in normal mouse serum resulted in some loss of tegumental microtriches but the tegument itself remained intact. Culture in hyperimmune rabbit serum resulted in complete loss of the tegument and disruption of subtegumental structures within 48 hr. The effects of immune mouse serum in vitro closely paralleled those previously seen during early immune damage in vivo. Immune serum taken 2 to 4 weeks after secondary intraperitoneal infection with T. crassiceps metacestodes caused loss of the larval tegument and degeneration of the subtegumental tissues after 7 days in culture, whereas immune mouse serum taken 6 weeks after secondary infection caused only minor ultrastructural changes and appeared to be less toxic to larvae than normal mouse serum. Although complement appeared to increase the number and severity of the tegumental lesions, the presence of heat-labile components of complement was not essential for mediation of tegumental damage by immune mouse serum.     

Nematospiroides dubius in mice selected for liability to infection: Modification of parasite biology through host selection

Brindley P. J. and Dobson C. 1982. Nematospiroides dubius in mice selected for liability to infection: modification of parasite biology through host selection. International Journal for Parasitology12: 573–578. Mice selected as liable (L) and refractory (R) over ten generations voided significantly more and less Nematospiroides dubius eggs compared with randomly mated (Rd) mice after primary infections with 100 larvae. There was little difference between the number of parasite eggs voided g^?1 faeces (epg) by individual mice on day 14 compared with day 15 after infection.However there was a significant diurnal variation in the egg values for individual mice but the mean differences observed between the R, Rd and L mice were maintained over a 24 h period. There was a strong correlation between both the total number and the number of female worms, surviving 21 days after infection, and the mean epg 14 and 15 days after infection. Female N. dubius produced more eggs in L mice and fewer eggs in R mice compared with worms in Rd mice. Similarly, worms grew longer in L mice and were shorter in R mice compared with parasites in Rd mice.     

Interactions between Taenia taeniaeformis and host cells in vitro: rapid adherence of peritoneal cells to strobilocerci

Engelkirk P. G., Williams J. F. and Signs M. M. 1981. Interactions between Taenia taeniaeformis and host cells in vitro: rapid adherence of peritoneal cells to strobilocerci. International Journal for Parasitology11: 463–474. Strobilocerci of Taenia taeniaeformis, incubated for l h in vitro with various combinations of serum and peritoneal cells from infected or non-infected rats, were examined at the ultrastructural level for evidence of cell adherence and tegumental damage. Maximal adherence and surface alterations occurred when larvae were incubated in the presence of cells and fresh serum. This was true regardless of whether the cells or the serum had been obtained from infected or non-infected donors. No tegumental damage was seen when parasites were incubated with or without cells in the absence of serum. Serum enhancement was either much reduced or abolished by heat treatment (56°C for 1 h). In the presence of EDTA, tegumental lesions still developed, but adherence of cells, especially those from non-infected rats, decreased markedly. The predominant cells interacting with the larval surface were eosinophils; these took up parasite material within phagosomes and appeared to strip microtriches from the tegumental free surface. Mast cells, some of which became degranulated, were also present in the adherent cell masses. The results indicate that potent non-specific effector mechanisms can rapidly damage the tegument of T. taeniaeformis, in vitro, in contrast to the failure of recognition and rejection by host defenses in vivo. Established strobilocerci are therefore not invulnerable but the balance of the host-parasite relationship in vivo must favor their survival.     

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.     

Histopathological appearances in primary and secondary infections with Strongyloides ratti in mice

Dawkins H. J. S., Muir G. M. & Grove D. I. 1981. Histopathological appearances in primary and secondary infections with Strongyloides ratti in mice. International Journal for Parasitology11: 97–103. The histological appearances of the skin, lungs and small intestines of mice with primary and secondary infections with S. ratti are described. When the skins of mice with a primary infection were examined, larvae were seen scattered throughout the dermis. An inflammatory reaction of neutrophils and eosinophils was first noted around larvae 12 h after infection. By 48 h, mononuclear cells were prominent. The intensity of the inflammatory reaction gradually increased to a maximum on the fifth day and the larvae were destroyed. Very few larvae were seen in the lungs; those observed were located in the alveolar spaces and were not surrounded by an inflammatory infiltrate. Worms in the small intestines were found mostly in the crypts of Leiberkuhn, and were probably located within the epithelial layer; there was no significant villous atrophy or cellular infiltration. Marked differences were found in the tissues of mice with secondary infections. In the skin, oedema and neutrophils and eosinophils were seen around worms as early as 2 h after infection. By 24 h after infection, there was a mixed inflammatory infiltrate and worms were undergoing disintegration. Larvae in the lungs were surrounded by polymorphonuclear and mononuclear cells 48 h and 72 h after infection and the engulfed larvae were undergoing lysis. Only a few worms were seen in the intestines of mice with a secondary infection; the histological appearances were similar to that found in animals with primary infections. It is suggested that the rapid development of an oedematous reaction in the skins of immune mice may facilitate the entry of larvae into the bloodstream and that inflammatory cells destroy many larvae in the lungs of immune mice.     

Damage and early destruction of Taenia taeniaeformis larvae in resistant hosts, and anomalous development in susceptible hosts: a light microscopic and ultrastructural study

Bortoletti G., Conchedda M. and Ferretti G. 1985. Damage and early destruction of Taenia taeniaeformis larvae in resistant hosts, and anomalous development in susceptible hosts: a light microscopic and ultrastructural study. International Journal for Parasitology15: 377–384. Taenia taeniaeformis larvae in resistant C57 mice have been studied from 5th to 15th day post-infection (L5–L15) both at the light and electron microscopic level. L5 stages were already damaged and total destruction occurred by approx. 15 days post-infection. In stage L5, unlike fertile larvae from C3H mice, the perilarval amorphous layer (PAL) was generally absent, and the host's cells were in close contact with the parasite surface. At this stage eosinophils were already present together with neutrophils and macrophages. Larvae were seen increasing in volume between stages L6 and L8, but remained constant from stages L9 to L14, while both the tegumental distal cytoplasm (TDC) and the subtegumental cellular layer (SCL) gradually decreased. In stages L10–L14 only a narrow TDC separated the larval cavity from host cells. After the larval tegument had been reduced in thickness the eosinophil lytic enzyme release onto the parasite surface contributed to produce a ‘hole’ in the TDC where host cells penetrated and gradually filled the larval cavity of L15, destroying the parasitic residues. Therefore anomalous small larvae (L50 and more) from C3H mice (susceptible host) have been studied: in these the scolex anlagen was absent or greatly reduced; the TDC was very narrow and the SCL greatly damaged. Outside the larva the ‘host tissue’ appeared as an unidentifiable amorphous material. These larvae cannot be considered ‘dead’ but are defined as sterile.     

Cuticular reactivity of the early larval stages of Ascaris suum: adhesion and degranulation of polymorphonuclear leukocytes of the surface of opsonized larvae of A. suum.

Binding of serum proteins (opsonization) on the surface of infective and early parasitic larvae of Ascaris suum is necessary to induce the adherence of polymorphonuclear leukocytes (PMN). When larvae are not pretreated in vitro with serum components, PMN do not adhere either to infective stage larvae or to parasitic larvae recovered from non-immune guinea pigs at 16, 25 or 48 h post oral infection. Adhesion of PMN occurs on all larval stages tested when they are first opsonized in vitro with the 7S fraction of immune serum. Opsonization with macroglobulins of immune serum or with Fab fragments of immune 7S protein does not induce the in vitro adherence of PMN. Adhesion of PMN to the larval surface results in reduction of Nitroblue tetrazolium to formazan precipitate at the larval surface, specifically in areas where cells are adherent, indicating oxidative enzyme action at the cuticle/PMN interface.     

Nippostrongylus brasiliensis: effects of immunity on the pre-intestinal and intestinal larval stages of the parasite

Nippostrongylus brasiliensis: effects of immunity on the pre-intestinal and intestinal larval stages of the parasite. International journal for Parasitology4: 183–191. Migration of the pre-intestinal larval stages of N. brasiliensis was studied in rats undergoing either primary or challenge infections. In rats undergoing a primary infection, more than 67 percent of larvae successfully migrated from the skin to the oesophagus by 70 h after infection, and subsequently over 90 per cent of these larvae became established in the small intestine as sexually mature adults. In immune rats undergoing a second infection, 46 per cent of larvae completed migration to the oesophagus by 70 h and of these, only 1·6 per cent became established in the intestine to produce eggs. These inhibitory effects on the pre-intestinal and intestinal larval stages were even more pronounced in immune rats undergoing a third or fourth infection and in addition, there was a prolonged sojourn and substantial retention of larvae in their lungs. There was no evidence that the immune response had an adverse effect on oesophageal fourth stags larvae as these organisms (obtained from immune donors) were able to establish and develop to maturity when transferred per os to normal animals.Syngeneic transfer of immune mesenteric lymph node cells to normal recipients, caused expulsion of parasites from the intestine but failed to effect migration of pre-intestinal larval stages. The implications of these findings are discussed in the context of current knowledge of the mechanisms of immunity to helminths.     

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.     

Resistance to Taenia pisiformis larvae in rabbits: immunization against infection using non-living antigens from in vitro culture.

Heath D. D. 1976. Resistance to Taenia pisiformis larvae in rabbits: Immunization against infection using non-living antigens from in vitro culture. International Journal for Parasitology6: 19–24. A 97 % protection of rabbits against infection with Taenia pisiformis larvae was stimulated by subcutaneous injections of killed larvae cultured in vitro for 6 or 9 days, combined with the concentrated culture media in which the larvae grew. Larvae cultured in vitro for 3 days or less stimulated only 60% protective immunity.Exogenous antigens produced by 10-day old larvae in vitro were collected free of contaminating macromolecules, and were partially characterized. There appeared to be 6 exogenous antigens. Rabbits were immunized with either frozen larvae, or the exogenous complex, or both, using one subcutaneous injection of antigens adsorbed on aluminium phosphate. Exogenous antigens stimulated an 88% protection against challenge infection 14 days later, while only 52% protection was stimulated by somatic antigens from frozen larvae. The effects of the two antigen complexes were not additive. The protective ability of exogenous antigens was destroyed by exposure to air.     

Assessment of in vivo antimicrobial activity of the carbene silver(I) acetate derivative SBC3 using Galleria mellonella larvae

The antimicrobial drug candidate 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver(I) acetate (SBC3) was evaluated for its ability to function in vivo using larvae of Galleria mellonella. A SBC3 concentration of 25 μg/ml inhibited the growth of Staphylococcus aureus by 71.2 % and Candida albicans by 86.2 % in vitro. Larvae inoculated with 20 μl of SBC3 solution showed no ill effects up to a concentration of 250 μg/ml but administration of 500 μg/ml resulted in a 40 % reduction in larval survival and administration of a dose of 1,000 μg/ml resulted in total larval death at 24 h. Larvae inoculated with S. aureus or C. albicans and subsequently administered SBC3 showed increased survival. Administration of SBC3 to larvae did not boost the insect immune response as indicated by lack of an increase in the density of circulating haemocytes (immune cells). The abundance of a number of proteins involved in the insect immune response was reduced in larvae that received 20 μl SBC3 solution of 100 μg/ml. This is the first demonstration of the in vivo activity of SBC3 against S. aureus and C. albicans and demonstrates that SBC3 does not stimulate a non-specific immune response in larvae.     

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.