Paul J. Brindley

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 Parasitology 12: 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.

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 Parasitology 15: 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.

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

Abstract 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.

Inheritance of immunity in mice to challenge infection with Nematospiroides dubius

Two lines of mice (Mus musculus) were selectively reared over 10 generations for high (H) and low (L) levels of immune response to Nematospiroides dubius, an enteric nematode parasite. Filial and backcross families were derived from the two parent lines. The mode of inheritance of the trait, immune response to challenge infection with N. dubius, was analysed by comparing the levels of infection in the parental, filial and backcross (BC) families of mice.The immunity of the F1 mice was found to be dissimilar to both parents, but was closer to the H value than to the level of immunity in the L mice. The backcross to H progeny showed levels of immunity approaching that of the H mice, whereas only two of four backcross to L families were low immune responders. Analysis of these results indicated that the inheritance of immunity in these mice to challenge infection with N. dubius was quantitative, partially dominant for high immune response, and additive, in nature.

Regulation of toxocariasis in mice selectively reared for high and low immune responses to Nematospiroides dubius

Test mice have been selectively reared for high (H) or low (L) immune responses to Nematospiroides dubius. After secondary infection with N. dubius, the L mice voided ten times as many eggs in their faeces as the H mice, and at necropsy, 71% versus 20% of the inoculum of N. dubius were recovered as adult worms from the L and H mice respectively. Furthermore, N. dubius were more fecund in the L than in H mice. High or low immune responsiveness was not restricted to N. dubius infection in these mice but was also observed during Toxocara canis infection. The migration of T. canis larvae from gut via the liver to skeletal muscle and CNS was inhibited in H versus L mice. Many more larvae were recovered from the livers of H compared with L mice which was indicative of greater immunity in the H mice. The protective immune response in H compared with L mice to both N. dubius and T. canis included pronounced eosinophilia and elevated antiparasite antibody titres.

Immunization and immunosuppression in mice reared for high or low immune responsiveness against Nema tospiroides dubius

High (H) and low (L) immune responder mice (Sitepu & Dobson, 1982) were immunized with 5, 10, 20, 40 or 80 Nematospiroides dubius larvae, drenched 3 weeks later with anthelmintic then challenged with 100 larvae. Size of the inoculum of larvae correlated positively with the numbers of N. dubius eggs passed in the faeces of all these mice after the immunizing dose, and the size of the inoculum of immunizing larvae was negatively correlated with faecal epg, worm numbers and lengths of worms recovered from H but not L mice after challenge infection with 100 larvae. Increasing the number of N. dubius larvae in the immunizing inoculum enhanced the immunization of H mice, whereas the L mice were progressively immunosuppressed by increasing numbers of larvae.

Oral, parenteral and paratenic infections of mice with Toxocara pteropodis

Oral, parenteral and paratenic infections of mice with Toxocara pteropodis. International Journal for Parasitology 16: 471-474. Groups of adult male CBA mice were inoculated with 7500 eggs of Toxocara pteropodis intragastrically, 2000 eggs subcutaneously or 2000 eggs intraperitoneally. Regardless of the infection route, larvae accumulated in the livers of these mice in comparable numbers. Following peroral infection, most larvae rapidly appeared in the liver with very small numbers passing through mesenteric lymph-nodes to the lungs. Intraperitoneal inoculation of eggs was followed also by a rapid accumulation of larvae in the liver, with larvae being recoverd also from lungs, intestines and other organs. Larvae from subcutaneous sites passed through the lungs en route to the liver, where they accumulated more slowly. Larvae within acutely-infected mouse lung and chronically infected flying fox liver which were fed to non-infected mice were capable of invading the livers of the latter, indicating a relict paratenic tendency. This marked hepatotropism of T. pteropodis indicates that larval accumulation in host livers is a goaldirected phenomenon independent of host capillary dimensions.

Partitioning innate and acquired immunity in mice after infection with Nematospiroides dubius.

Sera from donor mice (selected as refractory (R), random (Rd) and liable (L) to Nematospiroides dubius) after a single infection with 100 N. dubius larvae of 3 weeks duration, each transferred partial protection to the same degree in recipient C3H and Quackenbush mice. These results supported the conclusion that differences in the numbers of faecal N. dubius eggs voided by the R, Rd and L mice after 11 generations of selective breeding resulted from differences in their innate immunity.

Nematospiroides dubius: passive transfer of protective immunity to mice with monoclonal antibodies.

Nine hybridoma cell lines secreting monoclonal antibodies specific for Nematospiroides dubius were produced by fusion of the mouse myeloma cell line NS-1 to either spleen cells or mesenteric lymph node cells from mice repeatedly infected with N. dubius. Seven of the antibodies were identified as IgM and two as IgG1. Each monoclonal antibody bound to polypeptide epitopes on both infective larvae (L3) and adult worms. However, five antibodies bound preferentially to L3 and three to adult worms. All nine antibodies reacted with high molecular weight protein antigens. Passive protective immunity in Balb/c mice was demonstrated with monoclonal antibodies Nd2 and Nd3 in ascites fluid which stunted both male and female worms and reduced parasite fecundity.

Susceptibility of rats of infection withToxocara pteropodis

Infective eggs ofToxocara pteropodis were administered to Wistar rats via oral and parenteral routes. Third-stage larvae were recovered from the livers of suckling young 8 days after oral infection, and from livers and lungs after intraperitoneal or subcutaneous inoculation of eggs. These larvae were short-lived as none were found in suckling mice killed 2 weeks post-infection. Larvae were not recovered from tissues of rats aged 22 days or more when inoculated orally, indicating that refractoriness to infection develops rapidly with growth. Small numbers of larvae were recovered from the lungs of older rats 4 days after subcutaneous but not after oral inoculation. Adult male Buffalo and Fisher rats were also totally resistant to oral infection. Hence, rats differ from mice in their susceptibility toT. pteropodis.