Gender-specific gene expression in Brugia malayi

Brugia malayi is a mosquito-borne filarial nematode that causes lymphatic filariasis and elephantiasis in humans. The purpose of this study was to identify and characterize genes that are expressed differentially in male and female B. malayi in hopes of gaining new insight into the reproductive biology of the parasite. Two approaches were used. A 5' differential display PCR (splice leader differential display PCR, SL DD-PCR) was performed by PCR with splice leader and random primers on cDNA templates, and electronic subtraction was performed on expressed sequence tag (EST) cluster databases developed by the Filarial Genome Project (FGP). Gender-specific expression of candidate clones was confirmed by RT-PCR for six of 22 (27%) clones identified by DD and in seven of 15 (47%) clones identified by electronic subtraction. One clone was identified by both methods. Several female-specific clones had homology to known nematode genes that encode a fatty acid binding protein, a high mobility group protein, an eggshell protein, a glutamate-gated ion channel, and a collagen. However, most of the clones have no significant homology to known genes or proteins in computer databases. This project has confirmed the value of SL DD-PCR and electronic subtraction for analysis of gene expression in filariae. These two complimentary techniques may be generally applicable to the study of gender-specific (and by analogy stage specific) gene expression in other nematodes.

Efficacy of single dose combinations of albendazole, ivermectin and diethylcarbamazine for the treatment of bancroftian filariasis

In a 'blind' trial on 50 male asymptomatic microfilaraemic subjects with Wuchereria bancrofti infection, the safety, tolerability and filaricidal efficacy of a single dose of albendazole (alb) 600 mg alone or in combination with ivermectin (iver) 400 micrograms/kg or diethylcarbamazine citrate (DEC) 6 mg/kg was compared with a single dose of the combination DEC 6 mg/kg and iver 400 micrograms/kg over a period of 15 months after treatment. All but one subject, with 67 microfilariae (mf)/mL, had pre-treatment counts > 100 mf/mL. All 4 treatments significantly reduced mf counts, but alb/iver was the most effective regimen for clearing mf from night blood: 9 of 13 subjects (69%) were amicrofilaraemic by membrane filtration 15 months after treatment compared to one of 12 (8%), 3 of 11 (27%), and 3 of 10 (30%) in the groups treated with alb, alb/DEC, and DEC/iver, respectively. Filarial antigen tests suggested that all 4 treatments had significant activity against adult W. bancrofti; alb/DEC had the greatest activity according to this test, with antigen levels decreasing by 77% 15 months after therapy. All 4 regimens were well tolerated and clinically safe, although mild, self-limited systemic reactions were observed in all treatment groups. These results suggest that alb/iver is a safe and effective single dose regimen for suppression of microfilaraemia in bancroftian filariasis that could be considered for control programmes. Additional benefits of this combination are its potent, broad spectrum activity against intestinal helminths and potential relative safety in areas of Africa where DEC cannot be used for filariasis control because of co-endemicity with onchocerciasis or loiasis.