Fs. Toure et al., Sequence conservation of repeat 3 region of the gene coding for the 15 kDapolyprotein within human and simian Loa loa, J MED PRIM, 28(2), 1999, pp. 57-61
The human and simian strains of Lon loci microfilariae are morphologically
identical even though their periodicities vary. When using primate models (
,Mandrillus sphinx) of human loaisis for vaccination trials, the absence of
any ongoing simian L. loci infection must be demonstrated. Nested primers
derived from a human strain of L. loa (targeted on the repeat 3 region of t
he gene encoding the 15 kDa polyprotein: 15r3) amplified at 366 bp sequence
from simian L. loa genomic DNA and blood lysates from mandrills infected w
ith simian L. loa. This nested-PCR assay has been tested on 12 amicrofilare
mic (AMF) mandrills (without filarial microfilariae) and was positive in fo
ur mandrills. The nested-PCR product derived from simian L. loa genomic DNA
and from three of four AMF mandrills has been sequenced. No difference was
observed between the four sequences, which, in addition, were 99.18% ident
ical to the 15r3 of human L. loa. Therefore, the 15r3 sequence is conserved
within human and simian L. loa. These results suggest that the four PCR-pu
sitive mandrills without circulating microfilariae had occult simian L. loa
infections. The study demonstrates the ability of a nested-PCR assay to id
entify animals naturally infected with simian L. loa.