In vitro cultivation of third stage larvae of Wuchereria bancrofti to fourth stage: influence of some physico-chemical factors.

It has been reported that third stage larvae (L3) of Wuchereria bancrofti strain from Jakarta, molted to the fourth stage (L4) in vitro, in a simple culture medium supplemented with 10% human serum. In the present study, this culture medium has been used to examine the effects of some physico-chemical parameters on larval growth, development and molting of Wuchereria bancrofti from India. Lymph at 10% concentration enhanced the in vitro survival time of larvae. Molting of larvae from L3 to L4 stage has been obtained using human fetal lung cells in cellular co-culture and as a source of conditioned medium. Given these improvements in the medium supplementation, it has been observed that the age of L3s (duration of L3s maintenance within the mosquitos) is one of the most important parameters for the development of L3s in vitro. No molting was observed when one day L3s were used whereas, molting occurred with one or two weeks old L3s. On the contrary, when more than 3 weeks old L3s were used molting failed to occur even though duration of survival of L3s was improved and in this case, most of the larvae were degenerated.