Megaselia scalaris reared on Rhipicephalus (Boophilus) microplus laboratory cultures.

Different laboratory cultures of the acarine tick Rhipicephalus (Boophilus) microplus (Canestrini, 1888) (Ixodida: Ixodidae) were infested by small Megaselia scalaris (Loew, 1866) (Diptera: Phoridae) flies. Larvae of this species exhibited opportunistic parasitism predominantly on engorged female ticks, causing severe damage to their cuticle through which the flies were able to reach R. microplus internal organs, on which they fed until developing into pupae in the tick's remains. The flies were kept by continuous propagation on fresh ticks over six generations during which the same parasitoid behaviour was observed. Here we report on an ixodid tick laboratory culture used for rearing M. scalaris.

The treatment of mice with Lactobacillus casei induces protection against Babesia microti infection.

In this study, we report that administration of Lactobacillus casei confers protection to mice against the intracellular protozoan Babesia microti. Mice treated with L. casei orally or intraperitoneally were inoculated 7 days later with an infectious dose of B. microti. Mice treated with lactobacilli showed significant reduction in the percentage of parasitized erythrocytes (PPE) compared to untreated mice. When mice were inoculated intraperitoneally with L. casei 3 or 0 days before challenge with B. microti, the PPE was significantly lower compared to untreated mice and there were no differences between treated mice and mice immune to B. microti infection. When mice treated with live or dead L. casei were compared to mice inoculated with Freund Complete Adjuvant before a B. microti infection, a significant reduction of PPE was observed. These results show the protective effect of L. casei administered to mice against a B. microti infection and suggest that it might act by stimulating the innate immune system.

Effect of viable or dead Lactobacillus casei organisms administered orally to mice on resistance against Trichinella spiralis infection.

The capacity of viable, dead Lactobacillus casei and supernatant from L. casei culture, administered by oral route, to induce resistance in mice against Trichinella spiralis infection was evaluated. The percentage of adult worm reduction in the intestine five days after T. spiralis infection as compared with the worm burden in the control group fluctuated between between 53.1 and 58% in mice treated with viable L. casei, while reductions in animals treated with dead lactobacilli or supernatant from L. casei culture were of 44 and 32.5% respectively. The percentage of larvae per gram of muscle tissue reductions, as compared with controls, obtained 30 days after infection ranged from 48.4 to 70.7% in rodents which ingested viable L. casei compared with the percentage reductions of 65.9 and 24% obtained respectively in mice treated with dead lactobacilli or with L. casei supernatant. The protective response observed in the present study may be explained on the basis of 1) lactobacilli colonization of the intestine, 2) macrophage processing of dead lactobacilli in local immune tissues and presentation of L. casei antigens to Th1 cells which, in turn, produced IL-2 to activate B cells and other T cells.

Enhancement of resistance in mice treated with Lactobacillus casei: effect on Trichinella spiralis infection.

The ability of viable Lactobacillus casei, administered by an intraperitoneal route, to induce resistance in mice against Trichinella spiralis infection was tested. The percent reduction of adult worms in the intestine 5 days after T. spiralis infection observed in L. casei-treated animals, compared with those of the control group, fluctuated between 70.9 and 88.5%; reductions of larvae per gram of muscle tissue, evaluated at 30 days after infection, varied from 46.6 to 84.4% in L. casei-treated mice compared with controls. At 5 days after infection, intestinal villus height was shorter in T. spiralis-infected animals than in L. casei-treated or uninfected mice. There were fewer mast cells/crypt unit in L. casei-treated and uninfected mice than in T. spiralis-infected animals. Lactobacilli-treated mice showed twice as many mononuclear cells/crypt unit as T. spiralis-infected animals. The IFN-gamma serum level was higher in L. casei-treated animals at the time of worm challenge as compared with T. spiralis-infected or uninfected mice. The results indicate that: (1) L. casei increased resistance that acted against T. spiralis infection in mice, (2) this resistance apparently was directed against adult worms in the intestine.

Lectin activity from the cattle tick (Boophilus microplus) saliva.

The capability of Boophilus microplus saliva (BmS) and lectins to induce immunosuppression in mice and to agglutinate erythrocytes from distinct animal species were compared. CD-1 mice were distributed into groups (two for each substance) of 4-5 animals/group and treated intraperitoneally (i.p.) with 50 mg and 150 mg of BmS; concanavalin A (Con A); potato's lectin (PL), striped bean lectin (SBL) or 0.1 ml of phosphate buffered saline (PBS). All mice were immunized i.p. with 2 x 108 sheep erythrocytes (SE) 48 hours after treatment. Five days after immunization sera was obtained from mice to determine anti-SE antibody titer by direct hemagglutination. The mean antibody titers (Log2) obtained was 5.5 and 4.2 for BmS, 4.4 and 0 for Con A, 5.2 and 4.8 for PL, 4.6 and 0 for SBL and 7.4 for PBS. BmS and lectins were tested to agglutinate mouse (M), rat (Rt), rabbit (Rb), sheep (S) and human A (HA), human B (HB) and human O (HO) erythrocytes. BmS agglutinated Rb, S, HA, HB and HO erythrocytes at titer (Log2) of 1, 1, 6, 1 and 2 respectively. Con A and PL agglutinated erythrocytes from all species tested, while SBL agglutinated M, S and HA erythrocytes. A 50% inhibition of agglutination of HA erythrocytes by BmS was observed when D(+) Galactosamine and D(+) Glucosamine, at 0.2 M, were used. The results obtained indicate that BmS contains a weak nonspecific lectin which is inhibited by aminated sugars, and that induces immunosuppression in mice as other lectins.

Effect of three immunostimulants on the resistance against Trichinella spiralis infection in mice. (preliminary report).

Twenty eight NIH mice were divided into four groups of seven animals each. Mice in groups were injected intraperitoneally with Freund's complete adjuvant (FCA), Concanavalin A (Con A), Equimune (EI) and phosphate buffered saline (PBS), respectively, 7 days before infection with 300 Trichinella spiralis infective larvae per animal. Forty two days after infection all mice were sacrificed and processed by artificial digestion to determine the number of larvae per gram (LPG) of muscle tissue. The mean +/- SD of LPG obtained were 59.8 +/- 13.1, 17 +/- 8.5, 3.3 +/- 6.2 and 71 +/- 11.5 for groups FCA, Con A, EI, and PBS, respectively. Significant reductions in larvae worm numbers, compared with non-treated controls, were 76% and 95.3% in groups Con A and EI, respectively.

Comparison of five tests for the serologic diagnosis of myiasis by Gasterophilus spp. larvae (Diptera: Gasterophilidae) in horses and donkeys: a preliminary study.

Sera from 41 horses and 159 donkeys, from twelve States of México, were tested to ascertain anti-Gasterophilus circulating antibodies by double immunodiffusion (DD), counterimmunoelectrophoresis (CIE), indirect haemagglutination (IH), thin layer immunoassay (TIA) and diffusion-in-gel ELISA (DIG-ELISA) methods using crude somatic antigen from third instar larvae of G. intestinalis (DeGeer). At necropsy, 33/41 horses and 24/159 donkeys were found to be parasitized by G. intestinalis and/or G. nasalis (L.). Gasterophilus intestinalis was the species most commonly found in the equines. Analysis of the sera from the infected animals by DD showed positive results of 21.2% in horses and of 8% in donkeys. Screening the sera with CIE gave sensitivities of 69.7% in horses and of 32% in donkeys. Examination of the sera by IH showed positive results of 87.9% and of 48% in horses and donkeys, respectively. Testing the sera with TIA gave sensitivities of 93.9% in horses and of 96% in donkeys. Analysis of horses' sera by DIG-ELISA showed a sensitivity of 93.9%.

Non-specific resistance of sheep against Haemonchus contortus with Freund's complete adjuvant.

Six groups of four ovines each were injected intraperitoneally with Freund's complete adjuvant (FCA), at various times before, during, or after infection with 10 000 larvae (L3) of Haemonchus contortus per sheep. Animals in groups A and B received FCA on days 14 and 7, respectively, before infection. Ovines in group C were treated with FCA on the same day of infection; while sheep in groups D, E, and F were injected with the adjuvant on days 7, 14, and 21, respectively, after infection. Significant reductions in adult worm numbers compared with non-treated controls, as determined 42 days after infection, were of 30%, 34%, 45%, 52%, 56%, and 55% in groups A, B, C, D, E, and F, respectively. A significant correlation, between the time of FCA administration (referred to the day of infection) and the number of worms recovered at necropsy, was also observed.

A new method for serodiagnosis of sheep fascioliasis using helminth excretory-secretory products.

The diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) for antibodies to Fasciola hepatica was evaluated using adult fluke excretory-secretory products as antigen. The sensitivity and specificity of the test were compared with those of the indirect hemagglutination (IHA) technique. The results of the DIG-ELISA showed that the reaction zone diameters obtained with 42 sera from sheep with natural or experimental exposure to F. hepatica were significantly greater than those obtained with 85 sera from ovines infected with other parasites. Both sensitivity and specificity were 100% in the DIG-ELISA, whereas the sensitivity was 68.2% and the specificity was 100% in the IHA. The data suggest that the DIG-ELISA is a valuable serodiagnostic test for sheep fascioliasis.

A new method for diagnosis of Chagas' disease: diffusion-in-gel enzyme-linked immunosorbent assay.

The diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) for antibodies to Trypanosoma cruzi was evaluated using formalinized epimastigotes as antigen. The results obtained by DIG-ELISA were compared with those obtained with the indirect hemagglutination test. The results of the DIG-ELISA showed that the reaction zone diameters obtained with sera from individuals with past or present exposure to T. cruzi were significantly greater than those obtained with normal human sera. All the sera from Chagasic individuals had a positive reaction in the test, whereas sera from normal individuals and individuals with toxoplasmosis or cutaneous leishmaniasis had a negative result. A close correlation was observed between the reaction zone diameters and antibody concentration (expressed as log2 of the serum dilution). Excellent correlation was observed between results obtained by the 2 serological tests. The data suggest that the DIG-ELISA is a promising serological test for measuring antibodies to T. cruzi.

Serologic diagnosis of Oestrus ovis (Diptera:Oestridae) in naturally infested sheep.

Sera from eighteen control sheep supposed to be free from parasitism by Oestrus ovis Linnaeus, 1761, and from 100 sheep raised in an enzootic area of O.ovis infestations were tested to detect anti-Oestrus antibodies by double immunodiffusion (DD) and indirect haemagglutination (IH) tests with somatic crude antigens from first (L1), second (L2) and third (L3) instar of O.ovis larvae. At necropsy, eighty-eight out of 100 sheep from the O.ovis infested area were found to be parasitized while the eighteen control ovines did not show Oestrus larvae. Examination of the sera from the parasitized sheep by DD showed positive results of 42% for L1, 59% for L2 and 18% for L3. Screening the sera with IH gave sensitivities of 100% for L1, 100% for L2 and 97.7% for L3. Sheep, naturally parasitized by gastrointestinal nematodes, presented no cross immune reactions in DD tests with the three larval stages of O.ovis or with L2 larvae in IH tests.