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S Babayan

Publications and source records attributed to S Babayan.

5 recordsLinked to original sources
PubMed2005

Blood-feeding in the young adult filarial worms Litomosoides sigmodontis.

In this study with the filarial model Litomosoides sigmodontis, we demonstrate that the worms ingest host red blood cells at a precise moment of their life-cycle, immediately after the fourth moult. The red blood cells (RBC) were identified microscopically in live worms immobilized in PBS at 4 degrees C, and their density assessed. Two hosts were used: Mongolian gerbils, where microfilaraemia is high, and susceptible BALB/c mice with lower microfilaraemia. Gerbils were studied at 12 time-points, between day 9 post-inoculation (the worms were young 4th stage larvae) and day 330 p.i. (worms were old adults). Only the very young adult filarial worms had red blood cells in their gut. Haematophagy was observed between days 25 and 56 p.i. and peaked between day 28 and day 30 p.i. in female worms. In males, haematophagy was less frequent and intense. Similar kinetics of haematophagy were found in BALB/c mice, but frequency and intensity tended to be lower. Haematophagy seems useful to optimize adult maturation. These observations suggest that haematophagy is an important step in the life-cycle of L. sigmodontis. This hitherto undescribed phenomenon might be characteristic of other filarial species including human parasites.

Age Factors↗
PubMed2003

Examination of type material of two species of Litomosoides (Filarioidea: Onchocercidae), parasites from bats; taxonomic consequences.

Type material of Litomosoides hamletti Sandground, 1934 from Glossophaga soricina soricina in Brazil and L. penai Jiménez-Quirós & Arroyo, 1960 from Carollia perspicillata azteca in Costa Rica, was examined. The morphology of the spicules shows that these species belong to the carinii group. Their synonymy with L. guiterasi Pérez Vigueras, 1934, from Artibeus jamaicensis yucatanicus in Cuba, does not appear justified because they are distinct in several characters (body length, width of female, size and shape of buccal cavity and capsule, shape of right spicule). L. hamletti is a valid species; L. penai is closely related to it and is considered to be a sub-species, L. hamletti penai Jiménez-Quirós & Arroyo, 1960. The material recovered from Glossophaga spp., previously assigned to L. guiterasi by several authors, is identified as L. h. hamletti. L. guiterasi appears to be closely related to L. chandleri Esslinger, 1973; L. chitwoodi n. sp. (= Litomosoides sp. Chitwood, 1938) seems close to these species; all three are parasites of Artibeus spp.

Animals↗
PubMed2002

First account on the larval biology of a Litomosoides filaria, from a bat.

Litomosoides filariae are parasites of unrelated groups of hosts, including bats, marsupials, ancient and modern rodents. The four life cycles to-date elucidated, develop in terrestrial mammals and, at least experimentally, in the mite Ornithonyssus bacoti. A batch of mites was fed on an infected bat, Artibeus jamaicensis captured in Costa Rica, and 18 days later one infective larva was recovered. Its morphology was similar to that of other Litomosoides species, with the characteristic long buccal capsule. These first accounts on the larval biology of Litomosoides from Microchiroptera confirm the unity of the genus which supports the view that it has passed from one group of hosts to another by means of captures.

Acaridae↗
PubMed2001

B-cell deficiency suppresses vaccine-induced protection against murine filariasis but does not increase the recovery rate for primary infection.

To establish the role of B cells and antibodies in destroying filariae, mice lacking mature B cells and therefore unable to produce antibodies were used. Litomosoides sigmodontis offers a good opportunity for this study because it is the only filarial species that completes its life cycle in mice. Its development was compared in B-cell-deficient mice (BALB/c muMT mice) and wild-type BALB/c mice in two different in vivo situations, vaccination with irradiated larvae and primary infection. In all cases, mice were challenged with subcutaneous inoculation of 40 infective larvae. Vaccine-induced protection was suppressed in B-cell-deficient mice. In these mice, eosinophils infiltrated the subcutaneous tissue normally during immunization; however, their morphological state did not change following challenge inoculation, whereas in wild-type mice the percentage of degranulated eosinophils was markedly increased. From this, it may be deduced that the eosinophil-antibody-B-cell complex is the effector mechanism of protection in vaccinated mice and that its action is fast and takes place in the subcutaneous tissue. In primary infection, the filarial survival and growth was not modified by the absence of B cells. However, no female worm had uterine microfilariae, nor did any mice develop a patent infection. In these mice, concentrations of type 1 (gamma interferon) and type 2 (interleukin-4 [IL-4], IL-5 and IL-10) cytokines in serum were lower and pleural neutrophils were more numerous. The effects of the muMT mutation therefore differ from those in B1-cell-deficient mice described on the same BALB/c background, which reveal a higher filarial recovery rate and microfilaremia. This outlines B2-cell-dependent mechanisms as favorable to the late maturation of L. sigmodontis.

Animals↗