Df. Hoft, DIFFERENTIAL MUCOSAL INFECTIVITY OF DIFFERENT LIFE STAGES OF TRYPANOSOMA-CRUZI, The American journal of tropical medicine and hygiene, 55(4), 1996, pp. 360-364
Citations number
26
Categorie Soggetti
Public, Environmental & Occupation Heath","Tropical Medicine
Mucosal invasion is an important method of vector-borne transmission o
f Trypanosoma cruzi to human hosts. We previously have shown that low
numbers of virulent insect-derived metacyclic trypomastigotes (IMT) co
llected from the excreta of reduviid bugs were highly efficient in inf
ecting mice through gastrointestinal and conjunctival mucosa. However,
we have recently found that blood-form trypomastigotes (BFT) of T. cr
uzi cannot efficiently initiate mucosal infection after an oral challe
nge of the gastrointestinal tract. Evidence for systemic infection aft
er oral challenge with BFT was sought by microscopic parasitemia exami
nations of fresh blood, polymerase chain reaction analyses with DNA ex
tracted from mouse blood using primers specific for it nuclear repeat
present in thr T. cruzi genome, and by Western blots of parasite lysat
es probed with individual mouse serum. Oral challenge doses of 1,000-1
0,000 BFT were found to rarely initiate mucosal infection, In contrast
, 1,000 Ih IT delivered orally was a sufficient challenge for the cons
istent infection of 100% of control BALB/c mice. The exceptions infect
ed mucosally by BFT involved animals with mucosal defects due to traum
a or ulcerative/periodontal diseases. These data suggest that IMT have
uniquely specialized functions for mucosal invasion that are not norm
ally present in BFT.