Development of Various Leishmania (Sauroleishmania) tarentolae Strains in Three Phlebotomus Species

Abstract

Leishmania (Sauroleishmania) tarentolae is transmitted by reptile-biting sand flies of the genus Sergentomyia, but the role of Phlebotomus sand flies in circulation of this parasite is unknown. Here, we compared the development of L. (S.) tarentolae strains in three Phlebotomus species: P. papatasi, P. sergenti, and P. perniciosus. Laboratory-bred sand flies were membrane-fed on blood with parasite suspension and dissected on days 1 and 7 post blood meal. Parasites were measured on Giemsa-stained gut smears and five morphological forms were distinguished. In all parasite-vector combinations, promastigotes were found in Malpighian tubules, often in high numbers, which suggests that this tissue is a typical location for L. (S.) tarentolae development in sand flies. All three studied strains colonized the hindgut, but also migrated anteriorly to both parts of the midgut and colonized the stomodeal valve. Significant differences were demonstrated between sand fly species: highest infection rates, high parasite loads, and the most frequent anterior migration with colonization of the stomodeal valve were found in P. perniciosus, while all these parameters were lowest in P. sergenti. In conclusion, the peripylarian type of development was demonstrated for three L. (S.) tarentolae strains in three Phlebotomus sand flies. We suggest paying more attention to Phlebotomus species, particularly P. perniciosus and P. papatasi, as potential secondary vectors of Sauroleishmania.

Keywords: Leishmania tarentolae; Phlebotomus; Sauroleishmania; experimental infections; sand flies.

Figure 1

Infection rates and intensities of three Leishmania (S.) tarentolae strains in Phlebotomus papatasi on days 1 and 7 post blood meal (PBM). Intensities of infections were classified into three categories: light (<100 parasites/gut), moderate (100–1000 parasites/gut), and heavy (>1000 parasites/gut). Numbers of dissected sand fly females are given above the columns.

Figure 2

Localization of three Leishmania (S.) tarentolae strains in Phlebotomus papatasi on day 7 post blood meal. HG, hindgut; MTs, Malpighian tubules; AMG, abdominal midgut; TMG, thoracic midgut; CA, cardia; SV, stomodeal valve. Percent distribution of localization patterns among the infected females is shown in the top left of each stylized diagram. Only localizations present in more than 1% of females are depicted; for more details about each Sauroleishmania strain, see Figure S1.

Figure 3

Infection rates and intensities of three Leishmania (S.) tarentolae strains in Phlebotomus sergenti on day 1 and day 7 post blood meal (PBM). Intensities of infections were classified into three categories: light (<100 parasites/gut), moderate (100–1000 parasites/gut), and heavy (>1000 parasites/gut). Numbers of dissected sand fly females are given above the columns.

Figure 4

Summarized localization of three Leishmania (S.) tarentolae strains in Phlebotomus sergenti on day 7 post blood meal. HG, hindgut; MTs, Malpighian tubules; AMG, abdominal midgut; TMG, thoracic midgut; CA, cardia; SV, stomodeal valve. Percent distribution of localization patterns among the infected females is shown in the top left of each stylized diagram. Only localizations present in more than 1% of females are depicted; for more details about each Sauroleishmania strain, see Figure S2.

Figure 5

Infection rates and intensities of three Leishmania (S.) tarentolae strains in Phlebotomus perniciosus on day 1 and day 7 post blood meal (PBM). Intensities of infections were classified into three categories: light (<100 parasites/gut), moderate (100–1000 parasites/gut), and heavy (>1000 parasites/gut). Number of dissected sand fly females are given above the columns.

Figure 6

Summarized localization of three Leishmania (S.) tarentolae strains in Phlebotomus perniciosus on day 7 post blood meal. EPS, endoperitrophic space; HG, hindgut; MTs, Malpighian tubules; AMG, abdominal midgut; TMG, thoracic midgut; CA, cardia; SV, stomodeal valve. Percent distribution of localization patterns among the infected females is shown in the top left of each stylized diagram. Only localizations present in more than 1% of females are depicted; for more details about each Sauroleishmania strain, see Figure S3.

Figure 7

Phlebotomus perniciosus infected with Leishmania (S.) tarentolae strain ISS3200 on day 7 post blood meal: (a) colonization of stomodeal valve (Nomarski interference contrast, 100× magnification); (b) presence of flagellates in Malpighian tubules (Nomarski interference contrast, 200× magnification). Scale bar = 100 μm.

Figure 8

Leishmania (S.) tarentolae morphological forms in Phlebotomus sand flies: (A) elongated nectomonad; (B) short nectomonad; (C) metacyclic promastigote; (D) rounded metacyclic promastigote; (E) rounded paramastigote; (F) haptomonad. N, nucleus; K, kinetoplast (stained by Giemsa, 1000× magnification, scale bar = 10 μm).