Analysis of salivary gland proteins of the mosquito Armigeres subalbatus.

Quantitative studies of total salivary gland protein of Armigeres subalbatus mosquito revealed that the total salivary gland protein increased dramatically during the five days after emergence as adults. The amount of salivary gland protein of female and male mosquitos at day five after adult emergence were on the average 11.55 and 1.32 microg/pair gland respectively. SDS-PAGE studies showed that salivary gland protein profiles of Armigeres subalbatus demonstrated 9 major polypeptide bands of 68, 65, 60, 55, 40, 30, 28, 21, and 15 kDa. The 21 and 65 kDa bands were found only in the distal lateral region of the mosquito salivary gland and were depleted after the female mosquito took a blood meal.

Studies on filariasis in the Philippines I. results of a survey in the province of Sorsogon and in the New Bilibid Prison at Muntinlupa, Rizal

A survey for filariasis (wuchereriasis) was made among the inmates of the New Bilibid Prison at Muntinlupa, Rizal, and on two population groups in the province of Sorsogon, Luzon. The results of the examination of prisoners, who came from 45 different provinces, agree with previous observations that filariasis is unevenly distributed in the Philippines. A high incidence of infection was found in Sorsogon and a number of cases of hydrocele, chylocele, lymph scrotum and elephantiasis of the genital organs and lower extremeties was encountered. Clinical filariasis appears to be also common in other parts of Southeastern Luzon and should receive attention as an important medical problem. Only the microfilaria of Wuchereria bancrofti was encountered in the blood of 79 positive cases from different parts of the Archipelago and it exhibited nocturnal periodicity. (Summary and Conclusion)

Ivermectin and diethylcarbamazine trials in leaf monkeys (Presbytis cristatus) infected with Wuchereria kalimantani.

Clinical trials of Ivermectin in single oral doses of 200, 400, and 1,000 mg/kg body weight or in multiple doses of 200 mg/kg body weight for 5 consecutive days were performed in leaf monkeys (Presbytis cristatus) infected with Wuchereria kalimantani. Optimal microfilaricidal effect occurred at 200 mg/kg body weight. The drug was less effective than diethylcarbamazine in this animal model for human filariasis but had no adverse effects.

Differential recognition of Brugia malayi antigens by bancroftian filariasis sera.

Individuals residing in an area endemic to Wuchereria bancrofti infection were broadly categorised as endemic normals (EN), microfilaraemics (mf + ve) and elephantoids i.e., chronic lymphatic filariasis (EL). The immune status of these three groups was examined in terms of (i) specific antibody levels; (ii) ability to induce antibody dependent cellular cytotoxicity (ADCC) to microfilariae; and (iii) ability to recognise different microfilarial antigens by immunoblotting. All three groups of endemic residents were indistinguishable in their antibody levels as measured by ELISA with B. malayi microfilarial antigen. Many endemic normal sera and most elephantoid sera exerted strong cytotoxicity against W. bancrofti microfilariae whereas none of the mf + ve sera had any such activity. Immunoblotting studies revealed that a protein with mol. wt of 79 KDa was the only one among the proteins of B. malayi microfilarial extracts that was consistently recognised by sera from all endemic residents. Endemic normal sera and elephantoid sera, which exerted maximum cytotoxicity, together specifically recognised three proteins with molecular weights 25, 58 and 68 KDa and these three proteins could be among the candidate antigens that induce resistance to filarial infection.

A simple deterministic model for host-parasite relationship in Wuchereria bancrofti infection & its relevance to parasite regulation in human host.

A deterministic immigration-death model, which reflects the population dynamics of W. bancrofti in human host has been applied to study the relationship between vector and human infections. Application of the model showed that the rate of acquisition and loss of human infection were approximately equal (L = 0.130 and M = 0.129). The relationship of infective resting density (IRD) in vector population with maximum intensity (Imax) of infections and microfilaria prevalence (MFP) in human population were examined by using the least squares polynomial regressions. The fifth order polynomial regressions were found to be adequate to describe the observed pattern (Imax vs IRD: R2 = 0.8464, P = 0.0015; MFP vs IRD: R2 = 0.7246, P = 0.019). The observed relationships indicated that at an infective resting density of 0.26 per man hour or above, the density-dependent factors start regulating the human infections, which showed a declining trend, following this level.

Antigenic analysis of excretory-secretory products of Wuchereria bancrofti and Brugia malayi infective larval forms by SDS-PAGE.

Excretory-secretory (ES) products of W. bancrofti and the closely related B. malayi infective larval forms were analysed for their antigenic activity by SDS-PAGE followed by Western blotting as well as by gel elution-sandwich ELISA using filarial serum immunoglobulin-G (FSIgG) as a capture antibody. In W. bancrofti infective larval ES products, the protein molecules of 66, 46, 35, 33, 30 and 14 kDa molecular wt. showed antigenic activity by immuno blotting technique. In sandwich ELISA technique eventhough all SDS-PAGE fractions except ESA 6 (55-47 kDa) showed antigenic positivity, the fractions ESA 8 (37-31 kDa) and ESA 9 (31-25 kDa) showed high reciprocal antigen titre of 262144 and 32768 respectively. In B. malayi infective larval ES products, the protein molecules of 109, 102, 97 and 77 kDa molecular wt. showed reactivity with FSIgG by blotting technique, where as in sandwich ELISA except ESA 7 (47-37kDa), all fractions showed antigenic positivity. However, these fractions failed to show high antigen titre similar to W. bancrofti ES products with FSIgG.

Application of biotechnology in the identification of filarial larva in mosquitoes.

Current methods for detecting and identifying filariae in mosquitoes are laborious and time consuming. With today's technology, we can reasonably expect development of rapid, sensitive and specific assays for detecting and identifying filariae in naturally infected mosquito populations. Progress in developing such assays is reviewed.

Fractionation and characterization of urinary filarial antigen in bancroftian filariasis.

Urine samples from microfilaraemic patients were concentrated and fractionated by gel chromatography on Ultrogel AcA 44. Four protein fractions labelled as UFA C1, UFA C2, UFA C3 and UFA C4 were tested for filarial antigenicity by sandwich ELISA. UFA C1 and UFA C2 showed antigenic activity. On further analysis by SDS-PAGE, UFA C1 and UFA C2 showed antigenic components with MW ranging from 10.4 K to 123 K. UFA C1-1 and UFA C2-2 showed high antigen titre in ELISA. Urinary albumin was observed as a major component in UFA C2. Absorption of albumin from UFA C2 enhanced its antigenic activity considerably. As little as 0.01 pg antigenic protein per test was found to be sufficient for the detection of filarial antibody in ELISA. Biochemical characterization indicated a glycoprotein nature of UFA C2.

Filariasis in Tak Province, northwest Thailand: the presence of subperiodic variant Wuchereria bancrofti.

The microfilariae found in carriers at Tak Province, Northwestern Thailand were morphologically and morphometrically studied. It was found that the parasites conformed to that of W. bancrofti microfilaria. The microfilarial periodicity as determined from four carriers was found to be nocturnally (early evening) subperiodic type showing a distinct peak at 1800 hours.

Development of Brugia malayi in Mongolian gerbils previously exposed to Wuchereria bancrofti.

Twelve Mongolian gerbils, Meriones unguiculatus, were infected with 100 third-stage larvae of Wuchereria bancrofti. One month later these animals, along with 4 control animals, were given 100 third-stage larvae of Brugia malayi. Eleven of the 12 experimental animals and the 4 controls survived, and 8 of the experimental animals and all of the controls demonstrated microfilaremia after 3 months. The animals were killed at 6-months post-infection and examined for parasites. One W. bancrofti larva was found in one of the experimental animals, and 15% of the B. malayi given were recovered as adults from the testes, viscera, and carcass. Thirty-eight percent of the worms given to the controls were recovered from the testes, viscera, and pelt. The worms from the experimental animals also appeared to be smaller. This study suggests that gerbils are able to develop partial resistance to Brugia malayi following a previous infection with Wuchereria bancrofti.

Attempt to culture Wuchereria bancrofti in vitro.

Third-stage larvae of Wuchereria bancrofti recovered from laboratory raised Aedes togoi and Anopheles maculatus fed on a human volunteer were recovered by mass dissection methods and introduced into in vitro culture. LLC-MK2 cells were used as feeder cells, and the culture medium consisted of RPMI-1640 buffered with Hepes and sodium bicarbonate and supplemented with human AB serum. The third-stage larvae molted as early as 12 days and those surviving had all molted by 16 days. The fourth-stage parasites averaged in length from 1.4 mm to a maximum of 1.8 mm. Some larvae remained alive in culture as long as 40 days and while the worms were distorted in fixation, possible primodial cells of a spicule could be visualized in the rectal region. The cuticle also appeared to be separating in the posterior end. Although complete development was not achieved, it seems that with a continuing effort, success could be obtained using this culture system with feeder cells.