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PubMed1987

Filaricidal effect of mefloquine on adults and microfilariae of Brugia patei and Brugia malayi.

Mefloquine, DL-erythro-2,8-bis(trifluoromethyl)-alpha-(2-piperidyl)-4-quinoline methanolhydrochloride, a recently developed antimalarial drug shows filaricidal activity against larval and adult stages of Brugia patei and B. malayi maintained "in vitro". In the concentration range of 10 to 2 microM mefloquine paralysed and killed the filarial worms within 10 h and 3 d, respectively. The lethal effect of mefloquine treatment on larval and adult worms was shown by loss of motility as well as by decrease of lactate excretion by adults. Chloroquine at a concentration of 10 microM did not affect motility and survival of microfilariae and adults of B. patei. Addition of serum to the cultivation medium abolished the filaricidal effect, possibly due to the tight binding of mefloquine to serum proteins, thereby affecting the uptake of the drug into the parasite.

Animals↗
PubMed1987

Transfer of immunity to the microfilariae of Onchocerca lienalis in mice.

The model of Onchocerca lienalis microfilariae (mf) in CBA mice has been employed to examine the immunological mechanisms underlying the destruction of skin-dwelling mf in immunised hosts. Spleen cells from highly resistant donors transferred to naive, syngeneic recipients conferred significant protection against mf challenge, with up to 78% reductions in parasite recoveries. Levels of resistance afforded by adoptive transfers of immune cells were dose dependent and only significant above a threshold of 4 x 10(6) splenocytes. Mixed T and B lymphocytes elicited resistance in recipients, although neither cell population was protective alone. Immune serum evoked resistance to mf challenge by passive transfer, but only when collected shortly after booster immunisations of the donors. Xenogeneic sera from immunised rabbits or calves failed to confer protection to recipient mice. It is concluded that resistance to O. lienalis mf in mice is likely to be primarily governed by a thymus-dependent humoral response.

Animals↗
PubMed1986

Effect of milbemycin D against microfilariae of Litomosoides carinii.

The filaricidal effect of milbemycin D, a compound closely related to ivermectin, was studied in vivo and in vitro using Litomosoides carinii. Microfilaria (mf) densities in the peripheral blood of cotton rats, Sigmodon hispidus, were reduced to less than 3% of initial densities within 24 hours after treating either subcutaneously or orally at doses of 0.05 to 50 mg/kg body weight. In cotton rats treated with diethylcarbamazine at a single dose of 200 mg/kg, mf densities were reduced transiently but recovered to initial levels within 2 weeks, whereas they remained at less than 20% of the initial levels in rats treated with milbemycin D even with a single dose of 0.05 mg/kg. No microfilaricidal effect was observed in cotton rats treated with milbemycin D at a dose of 50 mg/kg for 5 consecutive days. The microfilaricidal effect of milbemycin D was also shown in vitro in RPMI 1640 medium. The minimal effective dose of this compound was estimated to be between 1 and 10 micrograms/ml of medium.

Animals↗
PubMed1987

Litomosoides carinii: characterization of surface carbohydrates of microfilariae and infective larvae.

The carbohydrate moieties of microfilariae (Mf) and infective larvae (L3) have been investigated by lectin-binding technique. Mf derived from three sources, namely, uteri (in utero), released in vitro from adults and from blood of rodents infected with Litomosoides carinii were examined by using fluoresceinated lectins. Wheat germ agglutinin (WGA) bound to these Mf and the binding was inhibited by N-acetyl glucosamine. In addition to WGA, Concanavalin A (Con A) and lentil lectin (LCH) bound to in vitro-released and in utero-derived Mf showing the presence of mannose moieties on their surface. In utero-derived Mf also showed binding with the agglutinins of Limulus polyphemus (LPA), peanut (PNA), Ricinus communis (RCA), Helix pomatia (HPA), Soyabean (SBA) and Dolichos biflorus (DBA) but not to that of Ulex europaeus (UEA) indicating the presence of additional carbohydrate molecules like sialic acid, galactose and N-acetyl galactosamine on their sheath. None of the lectins bound to the cuticle of exsheathed Mf. Treatment of blood-derived and in vitro-released Mf with certain proteases exposed additional binding sites for SBA, HPA, Con A and LCH. In case of L3, only PNA bound to the larvae isolated from infective mites Bdellonyssus bacoti, and the binding was inhibited by D-galactose. No such binding of the lectins was seen to the larvae that migrated to the pleural cavity of jirds indicating that there is considerable change on the parasite surface during their migration in the vertebrate host. Sheathed Mf and mite-derived L3 when incubated with immune rat sera, bind Con A and LCH lectins possibly due to the mannose components of the specific immunoglobulins that coat onto the Mf and L3.

Animals↗
PubMed1987

Setaria cervi: lipid biosynthesis from C14-labelled acetate and glucose in the two sexes and microfilariae.

Microfilariae (mf), males and females of Setaria cervi were able to synthesize several important classes of lipids and thus exhibited a functional lipid metabolism. The incorporation of the C14 label from acetate into lipids was relatively greater than that from glucose in adults, whereas label from glucose was incorporated to a greater extent in mf. Though only a small portion of these precursors, was utilized for the non-polar (NP) lipid synthesis, they were the preferred substrate for the polar lipid (P) synthesis; the P/NP ratios being 5.2 (mf), 1.63 (male) and 5.16 (female) for acetate and 1.23 (mf), 1.06 (male) and 2.25 (female) for glucose.

Acetates↗
PubMed1987

Effect of ivermectin on serum dependent cellular interactions to Dipetalonema viteae microfilariae.

The effects of ivermectin (Iv) on the filarial infection has been investigated using Dipetalonema viteae--Mastomys natalensis model system. In vitro, Iv (3 micrograms/ml) had no effect on the microfilariae (mf) in the presence or absence of serum from normal or infected Mastomys (NMS, IMS). However, the sera promoted cell-mediated cytotoxicity with macrophages or eosinophils to the mf when Iv was added at 3 ng/ml. Sera isolated from normal or infected Mastomys after subcutaneous treatment with Iv (100 micrograms/kg) (Iv-NMS, Iv-IMS) also induced cellular cytotoxicity to the mf in vitro. Available evidence suggests that Iv mediates the cellular cytotoxicity by complement activation by alternative pathway. Iv treatment of D. viteae infected Mastomys resulted in an initial mobilization of the mf into circulation followed by the death of both the mf and adults in vivo. There was enhanced antibody level in Iv treated infected animals and antibody dependent cellular cytotoxicity mediated by IgM seems to be predominantly involved in elimination of the mf. The serum containing these antibodies was effective in clearing the circulating mf from Mastomys on passive immunization. Thus, Iv seems to synergize host immune factors against D. viteae infection.

Animals↗
PubMed1986

Defense reactions of mosquitoes to filarial worms: effect of host age on the immune response to Dirofilaria immitis microfilariae.

The melanization response of Aedes aegypti black-eyed Liverpool strain (LVP) and Aedes trivittatus against intrathoracically inoculated Dirofilaria immitis microfilariae (mff) was assessed in mosquitoes less than 1, 14, 21, and 28 days after adult ecdysis. There was a significant decrease in the melanization response of A. aegypti 14 days of age and older at 1, 3, and 5 days postinoculation (PI) compared to less than 1-day-old mosquitoes. The response also was reduced significantly in 14- to 28-day-old A. trivittatus on days 1 and 3 PI. Although essentially 100% of recovered mff were melanized by day 5 PI in A. trivittatus, the amount of melanin deposited was much less than that seen in 0-day-old mosquitoes. Potential mechanisms responsible for a reduced immune competence in older mosquitoes and the possible relationship to vector potential are discussed.

Aedes↗
PubMed1986

Hemocyte-mediated melanization of microfilariae in Aedes aegypti.

The melanization response of adult female Aedes aegypti (black-eyed Liverpool strain) against intrathoracically inoculated Dirofilaria immitis microfilariae (mff) was assessed with transmission electron microscopy. The initial reaction involved the lysis of hemocytes at or near the surface of the parasite prior to the deposition of pigment. Subsequently, melanin formation was noted in the area of lysed cells and appeared to cascade onto the parasite surface. Observations suggest that melanin may be synthesized within certain hemocytes and released by exocytosis or upon cell lysis. Intact and disrupted nuclei and cytoplasmic elements from lysed hemocytes became numerous as mff became completely coated with melanin. A double membrane-like structure formed around the melanized mff and cellular debris during the later stages of the reaction, which eventually isolated the melanin capsule from hemolymph components. Results obtained are discussed in relation to the melanization response previously described for Aedes trivittatus.

Aedes↗
PubMed1986

Hemocyte cell surface changes in Aedes aegypti in response to microfilariae of Dirofilaria immitis.

This study involved the assessment of surface changes on hemocytes of Aedes aegypti black-eyed Liverpool strain in association with the melanization response against intrathoracically inoculated Dirofilaria immitis microfilariae (mff). Surface changes on hemocytes were identified using fluorescein-labeled wheat germ agglutinin (WGA). In mosquitoes eliciting a melanization response against inoculated mff, there was a 5-fold increase in the percentages of hemocytes exhibiting WGA binding compared with saline inoculated controls. Relationships of this hemocyte activation in relation to cell-mediated melanization responses of adult mosquitoes against mff are discussed.

Aedes↗
PubMed1986

Clearance of inoculated microfilariae of Brugia malayi by monoclonal antibodies in BALB/c mice.

A stable and long-lasting microfilaremia was developed by intravenous injection with 2 X 10(5) microfilariae (mf) of Brugia malayi into BALB/c mice. Mf density in mice was maintained at least at 30 to 40 mf/20 microliter blood for 4 weeks, then gradually decreased as the same as in the jird. However, mf inoculated were cleared from the blood within 3 weeks in the mice which was immunized with repeated intravenous injections with live mf. The effect of mf clearance was passively transferred into the mice with inoculated microfilaremia by intravenous injection of 0.2 ml serum from the immunized mice. For the analysis of the role of anti-mf antibodies, monoclonal antibodies (MABs) against mf of B. malayi were produced. An IgG1 MAB gave a significant mf reduction in mice and it promoted in vitro adherence of normal mouse spleen cells to mf.

Animals↗
PubMed1985

Filariasis transmission in Samoa. I. Relation between density of microfilariae and larval density in laboratory-bred and wild-caught Aedes (Stegomyia) polynesiensis (Marks) and wild-caught Aedes (Finlaya) samoanus (Gruenberg).

Transmission experiments of laboratory-bred and wild-caught Aedes polynesiensis and wild-caught Ae. samoanus on carriers with different levels of microfilaraemia showed that the percentage of mosquitoes infected, the average number and range of larvae found in each infected mosquito were directly proportional to the microfilarial densities in the carrier at the time of feeding. There was no difference between the results for laboratory-bred and wild-caught mosquitoes. Aedes polynesiensis fed on low carriers (around 20 Mf ml-1 and less) gave an average infection rate of 4.9%. Each infected mosquito harboured only one larva. A plot of the probit of percentage Ae. polynesiensis positive against the logarithm of microfilarial density showed a linear relationship. Using the regression line, at 95% confidence interval, a microfilarial density of 1 ml-1 would give an infection rate of 0.22-2.51%, a density of 0.1 Mf ml-1 an infection rate of 0.01-1.0%. The concentrating capacity of Ae. polynesiensis ranged from 0.70 to 4.74. As microfilaria densities decreased, concentration increased. The microfilarial intake, the subsequent worm burden and concentrating capacity were less in Ae. samoanus than Ae. polynesiensis. There was no evidence of any association between microfilarial density and concentration in Ae. samoanus.

Adolescent↗
PubMedDate not supplied

[Use of microfilaria treated with papain in the serodiagnosis of lymphatic filariasis caused by Wuchereria bancrofti (Var. pacifica)].

A standardised method for serodiagnosis of lymphatic filariasis W. bancrofti (var. pacifica) was performed. The authors used indirect fluorescent assay with papain treated microfilariae as source of antigen. Very high levels of antibodies were obtained in 96% microfilaremic patients. The geometric mean titers were 22.7 for healthy subjects and 605.5 for the filariasis patients. Cross reactivity was studied with two subcutaneous and one lymphatic filariasis. The geometric mean titers were 211.1 for Onchocerca volvulus, 105.6 for Loa-loa and 254 for Brugia malayi patients. No significant reactivity was observed with some other parasites.

Cross Reactions↗
PubMed1979

Tanzania Filariasis Project: a provocative day test with diethylcarbamazine for the detection of microfilariae of nocturnally periodic Wuchereria bancrofti in the blood.

In coastal Tanzania, an area where the microfilariae (mf) of Wuchereria bancrofti exhibit nocturnal periodicity, the administration of 2 mg diethylcarbamazine (DEC) per kg body weight in the daytime provoked mf to enter the peripheral blood. In persons on normal daily activities the daytime DEC provocative method proved to be as sensitive in detecting microfilaraemia as was the examination of night blood. Its use in routine surveys is therefore justified. Although mf densities by day and night were highly correlated (r = 0.83) they tended to be lower after provocative daytime DEC than in the corresponding night blood, except in very light infections. This method was also useful in assessing the parasitological response to mass chemotherapy with DEC, but, in comparison with the results of the night blood examinations, the sensitivity and magnitude of the counts in persons remaining positive progressively decreased as the period of DEC administration increased. A correction factor has to be calculated to take account of this, and/or additional night blood samples must be taken.The dose of 2 mg of DEC per kg body weight used was readily acceptable to the people in coastal East Africa, whose cooperation is difficult to obtain for night blood surveys. Apart from W. bancrofti, the only human filarial infection occasionally encountered in this area was Dipetalonema perstans. Because of the risk of a severe Mazzotti reaction the test is contraindicated in onchocerciasis endemic regions. Severe reactions may also occur in subjects with loaiasis.

Circadian Rhythm↗
PubMed1985

Ultrastructure of the melanization response of Aedes trivittatus against inoculated Dirofilaria immitis microfilariae.

Scanning and transmission electron microscopy revealed that intrathoracically-inoculated microfilariae (mff) of Dirofilaria immitis elicited a rapid and effective immune response in the hemocoel of Aedes trivittatus mosquitoes. Hemocyte lysis and melanization of inoculated mff began immediately following exposure to the hemolymph environment. Initial melanin accumulation occurred at any site along the surface of mff and rapidly increased in thickness. Hemocyte encapsulation generally described for insects did not occur, but hemocytes might be necessary for activation of the melanization response. Although intact hemocytes were never abundant, those that were present seemed to show an active secretion of membrane-bound vacuoles directed toward mff. Activated hemocytes were in close association, but never in direct contact with the parasite, and were most commonly seen in various stages of lysis. Numerous cell remnants were noted throughout the developing melanin capsule. Parasites were completely melanized by 24 hr postinoculation (PI). By about 3 days PI, a membrane began to form around deposited melanin and hemocyte remnants. This developed into a double membrane-like structure of 25-30 nm thickness and resulted in the enclosure and isolation of the mff, melanin deposits, and cellular remnants from hemolymph components. It is suggested that this membrane functions as a boundary to isolate the melanized parasite and prevents additional hemocyte involvement.

Aedes↗
PubMed1979

Chemotherapeutic studies on Litomosoides carinii infection of Mastomys natalensis. 8. The action of furazolidone on adult worms and microfilariae.

After oral administration of furazolidone in doses of 5 x 50 mg/kg and 1 x 100 mg/kg body weight to Litomosoides carinii--infected Mastomys natalensis microfilaraemia decreased continuously and was reduced by more than 98% 42 days after start of treatment. After the 5-day treatment all adult female and male worms were found dead and encapsulated within 2 weeks, whereas after the single dose 100% of the female parasites were encapsulated 28 days after treatment. In untreated animals quantiative examinations of the intrauterine stages showed an average number of 500 x 103 embryos per adult female worm. Following the 5-day treatment the number of embryos per female parasite was reduced after 42 days to 12.5 x 103, and after the single treatment to 26.9 x 103. By classification into 5 different stages (2- and 4-cell stages, Morula stage, "Horse-shoe" stage, "Ring" and "Brezel" stages, and intruterine microfilariae) an embryogram showed a continuous increase in pathologically-altered embryos during the whole observation period. The 2- and 4-cell stages suffered the most damaged. By 16 days after the end of the 5-day treatment and by 28 days after the single treatment all embryonic stages in the uteri were found to be pathologically altered. Furazolidone possessess high macrofilaricidal activity together with a considerable adverse effect on embryognesis and some delayed effect on microfilaraemia.

Animals↗
PubMed1977

[Etiological study of low fertility in eastern Gaboon. III. Filarial endemicity (Loa loa, D. perstans). Prevalence of microfilariae in hydroceles (author's transl)].

During an inquiry performed in Gaboon the prevalence of hydroceles had led to puncture systematically every vaginal flow. 68 fluids were so collected at the end of the inquiry. Subsequently the statistical analysis of the results in men seems to suggest a correlation between microfilaremia (Loa loa and D. perstans) and the prevalence of hydroceles. Microfilariae were found in 77% according to the following distribution: Loa loa seldom diagnosed in this kind of flow were detected in 10%; D. perstans although never reported so far in hydrocele fluids appeared to be present in 62%. O. volvulus more currently referred to in hydrocele liquids were scarcely traced.

Adult↗
PubMed1981

Identification of radioiodinated cuticular proteins and antigens of Onchocerca gibsoni microfilariae.

The filarial parasite of cattle, Onchocerca gibsoni, has been used to establish procedures of antigen identification with a view of applying these techniques to studies on human filarial parasites. Emphasis has been placed on methods suitable for use with small numbers of parasites. Microfilariae (mf) of O. gibsoni were extracted from nodular worms, purified and 125I-labeled using IODO-GEN in solid-phase. Radioactivity was shown to be confined to the cuticle of sectioned mf using the technique of electronmicroscope autoradiography. Radiolabeled mf were analysed by two-dimensional gel electrophoresis. Autoradiographs of 125I-labeled proteins of O. gibsoni mf were relatively complex, there being at least 32 proteins ranging in molecular weights from 20,000 to 120,000 and displaying considerable charge heterogeneity. Evidence was obtained that at least the major serum proteins of the host, albumin or immunoglobulin, were not absorbed on the surface of these uterine mf and detectable in the labeled surface protein patterns. Sera from infected cattle immunoprecipitated 5 labeled proteins from a Triton X-100 extract of 125I-labeled mf. Sera from either of two calves which had been given multiple injections of mf subcutaneously, and which had no detectable skin mf, recognised 6 additional proteins in this extract as well as 3 of the proteins recognised by sera from infected cattle.

Animals↗
PubMed1982

Mechanism of destruction of Brugia malayi microfilariae in vitro: the role of antibody and leucocytes.

Human and monkey leucocytes in serum from previously patent Brugia malayi infected monkeys adhered to and caused cytotoxicity to microfilariae of B. malayi in vitro. The phenomenon also occurred in human serum from confirmed cases of bancroftian and malayan elephantiasis. Adherence of leucocytes was not seen in serum from uninfected monkeys, monkeys with patent B. malayi infection and serum from rats infected with Breinlia booliati but now amicrofilaraemic. Immune serum failed to promote adherence of leucocytes to L3 of B. malayi. The activity was lost when the serum was either incubated with Protein A-bearing Staphylococcus aureus or heat inactivated at 56 degrees C for 30 min. Light and electron microscopic observations regarding the type of adhering cells and sequence of events following adherence are described.

Animals↗