Hymenolepis nana: Survival in the immunized mouse

Mice initially infected with Hymenolepis nana eggs became completely immune to challenge with mouse-derived cysticercoids (cysts) after more than 10 days. The host possessed at least two separated immune responses, one directed exclusively against reinfection with eggs (early response) and the other against cyst infection (late response). In two different mouse strains the responses showed markedly different duration both for the time lag prior to acquisition of the late response and for the survival of the initially infected worms, but were otherwise similar. The mice became immune to adult tapeworms and expelled the initially infected, destrobilated worms; this third immune response determines the longevity of H. nana in the mouse host. Thus, there is a strong indication that H. nana successively changes its immunogenicity during development, each stage stimulating immunity after a time lag. It is possible that the longevity of H. nana in a mouse strain depends on the length of time prior to acquisition of immune responses directed not against the tissue stage (early response), but against the lumen stages (late response and worm expulsion response).     

Hymenolepis diminuta: Biochemical properties of peroxidase activity in mitochondria

The biochemical properties of a peroxidase previously localized cytochemically in the mitochondria of Hymenolepis diminuta were determined. The method chosen was the o-dianisidine procedure in which the decomposition of hydrogen peroxide has been followed spectrophotometrically. Peroxidase activity was initially demonstrated in the mitochondrial pellet. Subsequently, mitochondrial pellets were sonicated and the membrane and supernatant fractions were tested for peroxidase activity. Enzyme activity was demonstrated in the membrane fraction. The enzyme displayed a pH optimum of 5.0, was ascorbate sensitive, and was inhibited by excess H₂O₂. Neither peroxidase nor catalase were observed in any other fraction of the tapeworm tissue, confirming previous cytochemical investigations.     

Hymenolepis nana: Protective immunity against mouse-derived cysticercoids induced by initial inoculation with eggs

Mice were almost completely resistant to a mouse-derived cysticercoid (cyst) challenge after 6 to 10 months following an initial immunizing inoculation with eggs of Hymenolepis nana. Previously uninfected control mice of the same age became infected with the cyst-derived tapeworms. There was no age resistance to H. nana in mice. Immunity against the cyst challenge was acquired by initial egg inoculation and blocked by injecting cortisone acetate just prior to the challenge. However, the number of worms recovered from mice given cortisone was significantly less than that from nonimmunized controls. Unexpected evidence was obtained that a few of the egg-derived tapeworms can survive for 6 or more months in some of the immunized mice, which are resistant to both egg and cyst challenges. The relative immunogenicity of oncospheres and cysts is discussed. It is strongly suggested that the cysts are different from the oncospheres in their immunogenicity, and, because of this, H. nana can complete its life cycle in the same immunized host. It is also suggested that the host possesses at least two separate immune responses: One is an early response directed exclusively against the oncosphere and/or the early postoncospheral stage (s) acquired within 2 days of egg inoculation, and the other is a late response against the cyst acquired after a time lag of unknown duration.     

Hymenolepis diminuta: Action of worm RNase against RNA

Hymenolepis diminuta possesses a tegumental ribonuclease (RNase) which hydrolyzes rat liver and degraded yeast RNA. Polyacrylamide gel electrophoresis and gel chromatography of rat liver RNA after incubation with intact worms demonstrated significant hydrolysis of the high molecular weight RNA fractions (28 S and 18 S), with the appearance of fractions of intermediate molecular weight (i.e., between 18 S and 4 S), as well as ethanol-soluble fractions. Hydrolysis of degraded yeast RNA (with a molecular weight of approximately 25,000) yielded a single ethanol-precipitable hydrolysis product, as well as ethanol-soluble hydrolysis products.     

Hymenolepis diminuta: The origin of protective antigens

Mice were infected orally with 1,6, or 30 cysticercoids of Hymenolepis diminuta. These were allowed to develop for different periods of time before elimination with anthelminthic, thus exposing the hosts to antigens from the prestrobilate, early strobilate, or fully strobilate worms. Other groups of mice were immunized by intraperitoneal (ip) implantation of a live strobilate worm or by ip implantation of live worms from cysticercoids excysted in vitro. Strong protection against challenge with a surgically transplanted strobilate worm was achieved by prior infection with 6 or 30 worms eliminated as early as Day 3 of infection. By this time these worms would not have strobilated. Conversely, a single worm, strobilating extensively over 16 days, stimulated only weak protection. Parenteral implantation of excysted worms protected mice but parenteral implantation of a strobilate worm had no effect. It is suggested that (i) the tapeworm protective antigens are primarily related to the scolex and/or the germinative region; (ii) the number of worms and the duration of antigenic stimulation in an immunizing infection determine the magnitude of a protective secondary response.     

Hymenolepis diminuta: Chloride fluxes and membrane potentials associated with sodium-coupled glucose transport

Glucose transport by Hymenolepis diminuta was inhibited when Cl^? in the bathing medium was replaced with acetate (C₂H₃O₂^Post?), but was unaffected when Cl^? was replaced with SCN^?. The relative effectiveness of the anions to inhibit influx of 7.4 mM Cl^? in the presence of 1 mM glucose was SCN^? > Cl^? > C₂H₃O₂^Post?. Glucose stimulated the influxes of 120 mM Cl^? and SCN^?, but had little effect on 120 mM C₂H₃O₂^Post? influx. While the diffusion rates of the anions were C₂H₃O₂^Post? > SCN^? = Cl^?, the preference of the glucose transport system for the anions was SCN^? > Cl^? > C₂H₃O₂^Post?. Efflux of Cl^? was not affected by the rate of glucose influx. Finally, microelectrode recordings of worms anesthetized with 2 mM arecoline revealed a transmembrane potential (TMP) of ?45 ± 3.6 mV (inside negative). Three to four minutes after addition of glucose (5 mM) there was a progressive hyperpolarization of the TMP to ?58 mV. A revised model of the glucose transport system that is consistent with previous observations on this organism is proposed.     

Hymenolepis nana: Immunogenicity of a lumen phase of the direct cycle and failure of autoinfection in BALBc mice

When $\text{BALB}\text{c}$ mice were given $\text{BALB}\text{c}$ mouse-derived cysticercoids (cysts) of Hymenolepis nana, only $\text{1}\text{43}$ mice became autoinfected, whereas most ($\text{31}\text{38}$) of dd mice given the same infection became massively autoinfected with mature worms. When $\text{BALB}\text{c}$ mice initially given cysts were challenged with eggs on Day 7, just before the patency of the primary infection, there was normal development into cysts, but almost none of them developed into adult worms. Thus, the failure of autoinfection of H. nana in $\text{BALB}\text{c}$ mice was not a result of failure of eggs to differentiate into cysts in the intestinal tissue, but a result of failure of these cysts to develop into adult worms in the lumen. The reasons why autoinfection does occur in dd and other strains of mice and not in the $\text{BALB}\text{c}$ strain are discussed in terms of the difference in onset of the late response in these strains of mice, ie., the response that is acquired after egg inoculation, and is directed against the lumen phase of cyst challenges. It is strongly suggested that (1) the lumen phase which follows cyst inoculation is highly immunogenic, but clearly differs from tissue phase which follows egg inoculation, (2) the autoinfection which occurs in some strains of mice is therefore not a result of no or poor immunogenicity of the lumen phase but is due to a delay of onset of the late response with the result that a secondary generation may mature, and (3) in other strains of mice, including $\text{BALB}\text{c}$, which acquire the late response within 15 days of initial egg inoculation, autoinfection normally does not occur after cyst infections.     

Hymenolepis microstoma: Mouse strain differences in resistance to a challenge infection

Antibody responses and host resistance to the tapeworm, Hymenolepis microstoma, were investigated using $\text{AKR}\text{J}$ and $\text{C}\text{3}\text{HeB}\text{FeJ}$ strains of mice. AKR mice were significantly more resistant than controls to a secondary infection following exposure to a 3-, 21-, or 40-day primary infection. During a primary infection, intestinal anti-worm antibody responses measured by an enzyme-linked immunosorbent assay were elevated in the more resistant AKR strain, whereas serum antibody titers did not differ between the two strains. However, during a secondary infection, serum IgA titers were higher in AKR mice than C3H mice. Suppression of the serum IgA anti-worm response by oral administration of lipopolysaccharide also suppressed resistance to a secondary infection. Intraperitoneal immunization with worm antigen resulted in a minor degree of protection in AKR mice. This protection was associated with increased intestinal antibody titers compared to mice not demonstrating protection. These results suggest that the protective responses observed in AKR mice relative to C3H mice reflect differences in mucosal antibody responses to H. microstoma.     

Hymenolepis nana: Maturation in an immunosuppressed unnatural rat host

When eggs of the dwarf tapeworm Hymenolepis nana, cycled exclusively and directly through mice for more than 10 years, were inoculated into previously uninfected inbred Fischer (F344) strain rats, they failed to mature in the rat intestinal lumen. Eggs of H. nana inoculated into the rat developed normally into cysticercoids (cysts) in the intestinal tissue, but thereafter failed to mature in the lumen except when the host was treated with cortisone acetate from the day of cyst maturation. The Fischer rat initially given eggs of H. nana became completely immune to egg challenge within 2 days of egg inoculation; no cysts derived from challenge eggs were found in the immunized rat. Immunosuppression, assessed by the success of cyst recovery in the tissue 4 days after egg challenge, had no promotive effect on the recovery of adult worms derived from eggs initially inoculated. Rats initially given eggs and immunosuppressed by cyclophosphamide or antithymocyte serum did not harbor any adult worms. Cortisone acetate treatment which was sufficient for eggs inoculated to mature (a total of 75 or even 200 mg, from Day 5 of egg inoculation) had no effects of immunosuppression, whereas cortisone acetate treatment which was sufficient for immunosuppression (a total of 150 mg from Day -2, two days prior to the initial egg inoculation) induced some adult formation as well. In addition, when mouse-derived cysts were inoculated into the rat instead of eggs, they also failed completely to mature even when the rat was treated with cyclophosphamide or antithimocyte serum. However, when the rat was treated with cortisone acetate from the day of cyst inoculation, the cysts developed into adult worms. Therefore, these results indicate that the Fischer rat clearly differs in its susceptibility to the tissue phase of egg inoculation and to the lumen phase of cyst inoculation of H. nana, and strongly suggest that the failure of maturation of H. nana in the unnatural host Fischer rat is not attributed to innate and/ or acquired immunity of the rat but to other nonimmunological mechanisms.     

Hymenolepis diminuta: membrane transport of glucose and beta-methylglucoside

Absorption kinetics of [¹⁴C]glucose and [β-methyl-¹⁴C]glucoside in Hymenolepis diminuta are reported. β-Methylglucoside (βMG) is a pure competitive inhibitor of [¹⁴C]glucose transport and has kinetic parameters, V_max and K_t, for transport similar to those reported for glucose. While absorbed ¹⁴C-βMG is not metabolized, transport of this glucose analog retains the general characteristics which have been established for glucose transport including: (1) Na⁺ dependence, (2) inhibition by K⁺, (3) sensitivity to phlorizin and various hexoses, (4) transport against an apparent concentration gradient, and (5) increase in worm water during accumulation. It is concluded that glucose and βMG are transported by the same system. The value of using βMG to study the mechanism of hexose transport and accumulation in H. diminuta is suggested.     

Hymenolepis microstoma: Ultrastructural localization of adenyl cyclase in the tegument

Peroxidase and phosphatase activities have been reported to be localized in the tegument of adult hymenolepidid tapeworms. In order to localize adenyl cyclase (EC 4.6.1.1) activity in the tegument of mature and gravid sections of Hymenolepis microstoma, 5-adenyl-imidodiphosphate was used as a substrate, and lead was used as a capturing agent. Results indicate that adenyl cyclase activity is present in the crypts between the microtriches of the mature sections and that activity is absent from the gravid sections.     

Loss of Hymenolepis diminuta from the rat

One, 5, 15 and 30 worm infections of Hymenolepis diminuta were established in juvenile or adult male (Hooded Rowett or Sprague-Dawley) rats. Worm numbers and weight, and egg output were determined from day 15 to day 85 post infection. Gradual worm loss occurred only from 15 and 30 worm infections. In 5, 15 and 30 worm infections worm weight decreased from day 19 to day 50 but no weight loss occurred in single worm infections. The size range of individual worms from a multiple infection of a single rat increased markedly following infection. Adult rats showed a greater worm loss and harboured smaller worms than juvenile rats. The data will fit either a competitive or an immunological model.     

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.     

Nippostrongylus brasiliensis and Nematodirus battus: Changes in numbers and weight during the course of infection

Nematodirus battus has been shown to be subject to a “self-cure” mechanism when lambs 6 weeks of age are infected with 60,000 larvae. It is proposed that this self-cure phenomenon is an immune response similar to that which occurs in rats infected with Nippostrongylus brasiliensis. Changes in the weight of adult Nematodirus sp. and Nippostrongylus sp. occur over the period of an infection in their hosts. Females of both species from high-dose infections increased in weight up to that time postinfection where most adult worms were present, then decreased in weight with the onset of rejection from the host. Male Nematodirus sp. showed a similar pattern of weight change to that of females but male Nippostrongylus sp. maintained a steady weight throughout the infection. The consequences of these changes in weight are discussed with relevance to expression of enzyme activities of the nematodes on a weight of individual nematode basis.     

Cotugnia digonopora: Transport of leucine

The uptake of leucine through the tegument of Cotugnia digonopora, a cestode found in the fowl intestine, occurs by a process of active transport. The K_t of transport is 0.87 mM and the V_max is 0.223 μmol/min/g. Uptake of the amino acid is competitively inhibited by valine (K_t = 1.30 mM). Potassium cyanide and 2,4-dinitrophenol do not completely block the entry of leucine into the parasite.     

Trichinella spiralis: Genetics of worm expulsion in inbred and F1 mice infected with different worm doses

The nematode Trichinella spiralis is rejected from the intestine at a time that is characteristic for each inbred strain of mouse. Previous work (R. G. Bell et al. 1982a) had empirically identified strong, intermediate, and weak phenotypes (NFR, $\text{C}\text{H}\text{He}$, and $\text{C57}\text{10}$ mice, respectively) in mice infected with 400 muscle larvae. It is shown that this classification applies to another eight inbred strains: SWR, $\text{DBA}\text{2}$, $\text{DBA}\text{1}$, LP, $\text{Bub}\text{Bn}$—all intermediate, and $\text{NZB}\text{BIN}$, C57L, A, and Mus molossinus—all weak. This phenotypic classification consistently applies with infections of 400–800 muscle larvae. Below doses of 300 muscle larvae, the strain designation of phenotype does not consistently apply. By this it is meant that the relative rejection rate changes for certain strains so that eventually some strains that were strong (NFR) or intermediate (AKR) responders to 400 muscle larvae become weak responders to 50 muscle larvae. Other strains increase their relative rejection time (B10 · BR, B10 · Q) while many do not change (NFS, $\text{C}\text{3}\text{Heb}\text{Fe}$, $\text{DBA}\text{2}$, $\text{DBA}\text{1}$). The phenomenon is most apparent in inbred parental strains rather than in F₁ crosses, and it represents a phenotypic variation in rejection time that is dependent on dose. It is also demonstrated that time of rejection is directly proportional to dose in all inbred and F₁ mouse strains that we have examined. Analysis of F₁ crosses shows that most have the rejection time of the strongest responding parental line, suggesting simple genetic control of strong, intermediate, and weak responses. Two F₁ crosses invalidated this theory. The $\text{DBA}\text{1}\text{×}\text{C3}\text{H}\text{He}$ (intermediate × intermediate) showed a strong response. The additive effects of parental rejection phenotype indicated that these lines could not be genetically identical for intermediate responsiveness. Similarly, the NFR (strong) × B10 · BR (weak) F₁ showed intermediate rejection, indicating partial dominance of $\text{C}\text{57}\text{B}\text{1}\text{10}$ genes over the strong responder NFR strain. Neither the primary expulsion time phenotype, phenotypic variation to low doses, or the rejection characteristics of F₁ crosses could be ascribed to genes linked to the major histocompatibility complex.     

Moniezia expansa: Subcellular distribution,kinetic properties of acetylcholinesterase and effects of inhibitors and anthelmintics

Acetylcholinesterase (EC 3:1:1:7) has been demonstrated biochemically within partially purified whole worm homogenates of Moniezia expansa. Linear activity occurred with temperature, enzyme concentration, and time. The pH optimum was 8.5 and the Michaelis constant 2.8 mM with inhibition by excess substrate. Inhibitor and specific substrate studies indicated that butyrylcholinesterase was probably absent. The molecular weight of AChE was in excess of 300,000. Greatest activity occurred in the 22,000 and 100,000g particulate fractions. Ultrastructural staining showed that activity was restricted to the ribosomes and cisternae of the rough endoplasmic reticulum. Quinacrine hydrochloride caused 48% inhibition of AChE at 10^?3M and haloxon (di(2-chloroethyl)-3-chloro-4-methyl-7-coumarinyl phosphate) caused 97% inhibition at 10^?4M. No appreciable inhibition (< 25%) occurred with 10^?4M bunamidine hydroxynaphthoate, bephenium hydroxynaphthoate, pyrantel tartrate, p-toluoyl phenyl hydrazone, dichlorphen, thiabendazole, mebendazole, fenbendazole, cambendazole, albendazole, parbendazole, oxibendazole, oxfendazole, praziquantel, piperazine adipate, arecoline hydrobromide, and sodium acetarsol.     

Hymenolepis diminuta: Partial characterization of membrane-bound nucleotidase activities (ATPase and 5′-nucleotidase) in the isolated brush border membrane

Adenosine triphosphatase (ATPase; EC 3.6.1.3) and 5′-nucleotidase (5′-NTase; EC 3.1.3.5) activities of the isolated brush border membrane of Hymenolepis diminuta have been studied. The pH optimum for ATPase activity is 7.4, and divalent cations are necessary for maximum activity; no Na⁺-K⁺ activated ATPase is present in the isolated brush border membrane. ATPase activity is inhibited by molybdate and phosphorylated monosaccharides, but not by N-ethylmaleimide (NEM), p-chloromercuribenzoate (pCMB), or fluoride. The pH optimum for 5′-NTase activity is 9.6–10.2, and divalent cations are necessary for maximum activity. 5′-NTase activity is inhibited by molybdate at pH 9.6 and 7.4, and activated by NEM and pCMB and pH 9.6 and 7.4, respectively; fluoride has no effect on 5′-NTase activity. Solubilization of the brush border membrane fraction in 1% sodium dodecyl sulfate has no inhibitory action on either enzyme activity.     

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.     

Association between the IRS1 and FTO genes regulates body weight in rabbits

Insulin receptor substrate (IRS) proteins play key roles in signal transduction in insulin and insulin-like growth factor signaling to control postnatal growth. The fat mass and obesity-associated (FTO) protein also play an essential role in postnatal growth. The aim of this study was to investigate the association between the IRS1 and FTO genes and the regulation of growth traits in rabbits. A total of nine synonymous SNPs were detected in the IRS1 coding sequence using direct sequencing, and the c.189G>T and c.2574G>A SNPs from two linkage disequilibrium blocks were further genotyped for association analysis in 216 New Zealand rabbits. The association results revealed that the TT genotype of c.189G>T and the AA genotype of c.2574G>A were significantly associated with higher body weight at 70 (BW70) and 84 (BW84) days of age and with higher average daily gain (P < 0.05). Linear-regression analysis revealed that the two-gene combination model of FTO c.499G>A and IRS1 c.2574G>A was associated with BW70 and BW84. The combination model of the GA genotype of FTO c.499G>A with the AA genotype of IRS1 c.2574G>A was associated with preferred values for BW70 and BW84. The performance values for the FTO c.499G>A genotypes after stratification with regard to the IRS1 c.189G>T genotypes revealed that the TT genotype of IRS1 c.189G>T reduced the FTO c.499G>A significance associated with BW70 and BW84. Together, our data indicated that the IRS1 gene was associated with growth traits in rabbits. The IRS1 and FTO combination model may be exploited to assist breeders in selecting rabbits with preferred body weight.