Experimental infection and protection against ... - TI Pharma

130 Chapter 7
Abstract
The portfolio of Plasmodium falciparum (Pf) strains for controlled human
malaria infections (CHMI) primarily consists of NF54 and its clone 3D7.
Availability of additional strains will allow better evaluation of efficacy of
experimental vaccines and drugs, and understanding of immunological
protection mechanisms.
NF135 was isolated from a Dutch patients who acquired malaria whilst travelling
in Cambodia. Parasites were adapted to continuous culture and cloned. Clone
NF135.C10 consistently produced gametocytes and generated substantial
numbers of sporozoites in Anopheles mosquitoes. NF135.C10 was tested in a
CHMI trial in comparison with NF54 for parasitological, immunological and
clinical parameters. Two groups of five malaria-naive volunteers were exposed
to bites of five NF54 or NF135.C10 infected mosquitoes.
NF135.C10 parasites diverged from NF54 parasites by drug sensitivity and
genetic marker profiles. Both NF135.C10 and NF54 were infectious to humans.
Three out of five volunteers challenged with NF135.C10 and four out of five
challenged with NF54 developed parasitemia after seven to eleven days as
detected by microscopy. The two strains showed great similarity in prepatent
period, kinetics of parasitemia, clinical features and cellular immunological
responses.
In conclusion, we successfully established a new field strain of Pf that can be
used in CHMI and vaccine studies.