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Infection and Immunity, December 2000, p. 6561-6566, Vol. 68, No. 12
Unité d'Immunophysiologie et
Parasitisme Intracellulaire, Institut Pasteur, 75724 Paris Cedex
15, France
Received 3 May 2000/Returned for modification 14 June 2000/Accepted 6 September 2000
So far, studies of Leishmania persistence in mice have
used injections of parasites administered either intravenously in the tail vein or subcutaneously in the footpad. These routes poorly reflect
the natural conditions when the sandfly delivers metacyclic promastigotes intradermally. In this study B10D2 and BALB/c mice were
inoculated within the ear dermis with 104 Leishmania
major metacyclic promastigotes. The parasite load was monitored
by quantitative PCR in different tissues from the dermal inoculation
site to distant tissues. The two sites of multiplication and
persistence of parasites were the site of L. major
inoculation and the draining lymph node (DLN), with a different pattern
in the two mouse inbred lines. These two organs were the only sites harboring parasites 12 months postinoculation, with the DLN of BALB/c
mice harboring around 107 parasites, a stable load from
months 3 to 12. In these two sites, 8 and 12 months after inoculation,
interleukin 4 (IL-4), gamma interferon, and inducible nitric oxide
synthase transcripts parallel the parasite load while IL-10 transcript
levels remain high. In addition, at early time points until month 3, parasite DNA was also detected in distant tissues such as the
contralateral noninoculated ear or the tail skin, indicating that blood
was at least transiently disseminating the parasites. In contrast,
L. major DNA in liver, spleen, and femoral bone marrow
remained sporadic in mice of both lines. This study is discussed within
the framework of Leishmania transmission from the
vertebrate host to the sandfly vector, a complex process still poorly understood.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Leishmania major Reaches Distant Cutaneous Sites Where
It Persists Transiently while Persisting Durably in the Primary Dermal
Site and Its Draining Lymph Node: a Study with Laboratory
Mice

*
Corresponding author. Mailing address: Institut
Pasteur, Unité d'Immunophysiologie et Parasitisme
Intracellulaire, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
Phone: (33) 1 45 68 81 70. Fax: (33) 1 40 61 31 69. E-mail:
lnicolas{at}pasteur.fr.
Present address: Research Policy and Cooperation, World Health
Organization, Geneva, Switzerland.
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