Raymond Jacobson - Academia.edu (original) (raw)

Papers by Raymond Jacobson

Infection, Genetics and Evolution, 2008

An intraspecific study on Phlebotomus papatasi, the main proven vector of Leishmania major among ... more An intraspecific study on Phlebotomus papatasi, the main proven vector of Leishmania major among the members of the subgenus Phlebotomus, was performed. The internal transcribed spacer 2 (ITS 2) of rDNA and the ND4 gene of mt DNAwere sequenced from 26 populations from 18 countries (and Yemen), and compared. Samples also included three other species belonging to the subgenus Phlebotomus: P. duboscqi, a proven vector of L. major in the south of Sahara (three populations from Burkina Faso, Kenya and Senegal), P. bergeroti, a suspected vector of L. major (three populations from Oman Sultanate, Iran and Egypt), and one population of P. salehi from Iran. A phylogenetic study was carried out on the subgenus Phlebotomus. Our results confirm the validity of the morphologically characterized taxa. The position of P. salehi is doubtful. Variability in P. papatasi contrasts with that observed within other species having a wide distribution like P. (Paraphlebotomus) sergenti in the Old World or Lutzomyia (Lutzomyia) longipalpis in the New World. Consequently, it could be hypothesized that all populations of P. papatasi over its distribution area have similar vectorial capacities. The limits of the distribution area of L. major are correlated with the distribution of common rodents acting as hosts of the parasites. #

Eastern Mediterranean health journal = La revue de santé de la Méditerranée orientale = al-Majallah al-ṣiḥḥīyah li-sharq al-mutawassiṭ, 2003

This study of cutaneous leishmaniasis in Jericho city and the adjacent Aqbat-Jaber refugee camp i... more This study of cutaneous leishmaniasis in Jericho city and the adjacent Aqbat-Jaber refugee camp investigated the seroprevalance of Leishmania major and the risk factors associated with acquiring the disease. Clinical and parasitology identification of cases showed children and young men were more affected, with the head most affected in children. Enzyme-linked immunosorbent assay (ELISA) was used to test sera from 190 individuals. The overall seroprevalence of cutaneous leishmaniasis was 26.3%. A case-control study of 247 individual in 37 households showed that a higher level of education of the head of the household and having children sleep under bed nets were significantly related to a lower incidence of cutaneous leishmaniasis.

Journal of the American Mosquito Control Association, 1997

Sugar meals of plant origin are an important component of the sand fly diet. We show that sugar s... more Sugar meals of plant origin are an important component of the sand fly diet. We show that sugar solution baits have potential as vehicles for phlebotomine sand fly control. In the laboratory, adult Phlebotomus duboscqi Neveu-Lemaire and Sergentomyia schwetzi (Adler, Theodor, and Parrot) that have consumed an aqueous sucrose solution containing Bacillus sphaericus Neide toxins and are subsequently eaten by larvae produce significant larval death (P < 0.01). In the field, when vegetation near animal burrows and eroded termite mounds was sprayed with sucrose solution with or without incorporation of the larval toxicant B. sphaericus, 40% of female sand flies fed in situ. Dispersing B. sphaericus-carrier sand flies caused significant larval mortality (P < 0.01) in resting and breeding sites in animal burrows 10-30 m from the sprayed vegetation for 2-12 wk posttreatment. Also, adult sand fly populations breeding and resting inside animal burrows were significantly reduced (P < 0...

The American journal of tropical medicine and hygiene

The plant feeding of Phlebotomus papatasi and the effects of plant diets on the Leishmania major ... more The plant feeding of Phlebotomus papatasi and the effects of plant diets on the Leishmania major infections were investigated. Plant-fed flies had small free particles and membranous shreds in their gut that were stained by calcofluor as cellulosic plant tissues. They were found in 34.0% of the female and 14.3% of the male sand flies following feeding on the caper plant (Capparis spinosa). No plant residues were found in 54 females that had been fed on plant-derived honeydew secretions of Aphis craccivora offered on a branch of the host plant. Calcofluor-stained particles were also absent from the gut lumen of unfed flies. The proportion of sugar feeding, regardless of the intake of plant tissue, in the series that had been offered caper plant or honeydew was estimated by testing for the presence of fructose in the gut. The proportion of fructose-positive flies in each series, among both males and females, was 45%. Plant feeding in the field was demonstrated by finding tissue residues in the gut of 32.8% of female and 10.3% of male P. papatasi from the Jordan Valley. Feeding on specific plants was demonstrated using baits of branches suffused with food dye and finding the dye marker in wild-caught P. papatasi. The influence of plant diets on L. major infections in P. papatasi was as follows: Malva nicaeensis and the honeydew of Icerya purchasi produced thriving parasitemias; however, feeding on Ricinus communis, Capparis spinosa, and Solanum luteum caused> 50% mortality and deformation of parasites in 88%, 55%, and 46% of the infections, respectively. This type of injury was also observed in 21 of the 38 mature infections in field-caught flies. These observations imply that some plant diets of P. papatasi in the wild impair L. major infections in the flies, thereby decreasing their capacity to transmit leishmaniasis.

Microbes and infection / Institut Pasteur, 2005

Evidence is provided for genetic and biological variation among Leishmania major strains that cor... more Evidence is provided for genetic and biological variation among Leishmania major strains that correlates with their geographical origin. The host-parasite relationship also appears to be specific. Great gerbils, Rhombomys opimus, and fat sand rats, Psammomys obesus, are the main reservoir hosts in Central Asia and the Middle East, respectively. However, the Central Asian parasite failed to infect the Middle Eastern rodent host in the laboratory, and vice versa. A permissively primed intergenic polymorphic (PPIP)-PCR and a single-stranded conformation polymorphism (SSCP)-PCR exposed genetic polymorphism among 30 strains of L. major from different geographical regions. This was verified by subsequent sequencing of DNA from the same strains using four genomic targets: (a) the NADH-dehydrogenase (NADH-DH) gene, (b) the 6-phosphogluconate dehydrogenase (6PGD) gene, (c) the ribosomal internal transcribed spacers, and (d) an anonymous DNA sequence originally amplified with random primers. ...

Journal of medical entomology, 1989

The response of Phlebotomus papatasi Scopoli to traps baited with manure or water was used to com... more The response of Phlebotomus papatasi Scopoli to traps baited with manure or water was used to compare the behavior of flies near rodent burrows (breeding sites) and dispersing flies in fallow fields. The degree of response in each biotype was defined for each bait by the difference between catches in baited and unbaited traps. Manure bait attracted twice as many flies near the burrows and 2.7 times more flies in the field compared with unbaited traps. In both locations, the manure bait increased the capture of males and nongravid females, whereas gravid females were attracted only near burrows and not in the fields. The catch in the fields with water bait was similar to the unbaited control. However, near burrows, water bait captured more males and gravid females, but not nongravid females. These results demonstrate specific behavioral patterns of the dispersing P. papatasi population.

Pathogens and Global Health

Rabbits were immunized with brain, muscle or haemolymph of adult Sarcophaga falculata, and groups... more Rabbits were immunized with brain, muscle or haemolymph of adult Sarcophaga falculata, and groups of Sarcophaga were then fed on serum collected from the immune rabbits. Rabbit serum immunoglobulins on the tissues of the fed flies were demonstrated by the indirect fluorescent antibody method, using fluorescent goat-anti-rabbit IgG. The antibodies were specifically demonstrated in the tissues that had been used as immunizing antigen. It was also shown that antibodies unrelated to fly antigens pass through the fly gut and react with the specific antigens.

The American journal of tropical medicine and hygiene, 2004

The predominant sand fly species collected inside houses in Kfar Adumim, an Israeli village in th... more The predominant sand fly species collected inside houses in Kfar Adumim, an Israeli village in the Judean Desert that is a focus of cutaneous leishmaniasis, was Phlebotomus papatasi, which was also caught attempting to bite humans. Phlebotomus sergenti, which is rarely seen inside houses, constituted the predominant sand fly species in caves near the village. Leishmania isolates from Ph. sergenti and humans typed as Leishmania tropica. Sand fly and human isolates produced similar small nodular cutaneous lesions in hamsters. Isolates produced excreted factor (EF) of subserotypes A(9) or A(9)B(2), characteristic of L. tropica and reacted with L. tropica-specific monoclonal antibodies. Isoenzyme analysis consigned the strains to the L. tropica zymodemes MON-137 and MON-275. Molecular genetic analyses confirmed the strains were L. tropica and intraspecific microheterogeneity was observed. Genomic fingerprinting using a mini-satellite probe separated the L. tropica strains into two clust...

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1998

A direct enzyme-linked immunosorbent assay (ELISA) using species-specific monoclonal antibodies w... more A direct enzyme-linked immunosorbent assay (ELISA) using species-specific monoclonal antibodies was developed for the detection and identification ofLeishmania in sandflies. A titration of mock-infected Phlebotomus papatasi showed that fewer than 2000 L. major promastigotes could be detected. The percentage of infected l? papatasi collected in the field, as determined by dissection, was compared to that revealed by the ELISA. Both methods gave similar results, irrespective of whether the flies were caught by sticky papers or light-traps. The percentage of infected flies determined by either method was also similar in experimentally infected colony reared sandflies.The ELISA can be carried out using multiple species-specific antibodies, and is as accurate as identification of infected sandflies by microscopical examination. The technique should be useful for identifying sandfly species involved in transmitting different species of Leishmania, and for rapid assessment of leishmanial infection rates in endemic regions.

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1990

The effect of Leishmania glycoconjugate in the vector was investigated using Phlebotomus papatasi... more The effect of Leishmania glycoconjugate in the vector was investigated using Phlebotomus papatasi artificially infected with a Leishmania major strain that this vector does not transmit in nature. Glycoconjugate of the vector-specific strain of L. major was added to the infective meals of some fly groups and the success of infections with or without this substance was compared 4 d later. In the absence of glycoconjugate the parasites survived in 15.6% of the flies, while the addition of 0.5 mg/ml and 2 mg/ml raised the rate of infection to 34.3% and 63.0% respectively. Undiaested blood was found in the stomach of 7.8% of th: infected ties, whereas following meals with parasites and 2 mg/ml glycoconjugate ii was present in 37% of the flies. The results demonstrated that this glycoconjugate increased the viability of the parasites in the unsuitable vector and delayed digestion of the infective meals. In a parallel experiment the glycoconjugate of L. donovani did not affect the survival of the parasites.

The Journal of Eukaryotic Microbiology, 1997

T h e secretion of cellulose-degrading enzymes by Leishmania promastigotes in culture and in the ... more T h e secretion of cellulose-degrading enzymes by Leishmania promastigotes in culture and in the sandfly vector was demonstrated. Two types of activity of cellulase enzyme-complexes were measured: endoglucanases, which randomly cleave cellulose chains and cellobioydrolases, which remove cellobiose from the nonreducing end of the molecule. The assays demonstrated that enzymes with these activities were secreted into the culture medium by Leishmania major, L. donovani. and L. bmzilierzsis. These activities were also found in cultures of Sauroleishmania agamae, Leptomonas seymouri, Herpetomonas muscarum, Crirhidia fasciculata and Trypanosoma brucei brucei that had a relatively low endoglucanase activity. Both endoglucanase and cellobiohydrolase activities were found in the gut of L. major-infected Phlebotomus papatasi, while gut preparations of uninfected sandflies had only cellobiohydrolase activity. The similar growth of L. major parasites in medium supplemented with either cellulose or glucose suggests these parasites can utilize cellulose.

Proceedings of the Royal Society B: Biological Sciences, 1991

Leishmania major parasites ingested with host blood by the sandfly Phlebotomus papatasi multiply ... more Leishmania major parasites ingested with host blood by the sandfly Phlebotomus papatasi multiply confined within the peritrophic membrane. This membrane consists of a chitin framework and a protein carbohydrate matrix and it is secreted around the food by the insect midgut. Histological sections of infected flies show lysis of the chitin layer in the anterior region of the peritrophic membrane that permits the essential forward migration of a concentrated mass of parasites. Both the location and the nature of this disintegration are specific to infected flies. At a later stage the parasites concentrate in the cardiac valve region and subsequently this segment of the fore gut loses its cuticular lining. We have found that chitinase and N-acetylglucosaminidase are secreted by cultured L. major promastigotes, but not by sandfly guts. Hence lysis of the chitin layer of the peritrophic membrane could be catalysed by these enzymes of the parasites. Activity of both enzymes was also observed in other trypanosomatids, including L. donovani, L. infantum, L. braziliensis, Leptomonas seymouri, Crithidia fasciculata and Trypanosoma lewisi.

Physiological Entomology, 2008

ABSTRACT Abstract In arid areas, Phlebotomus papatasi obtains essential carbohydrates by feeding ... more ABSTRACT Abstract In arid areas, Phlebotomus papatasi obtains essential carbohydrates by feeding on green tissues of plants. There is a great variation in sugar content, metabolic rates and dark respiration between conspecific plants, and also between branches and leaves of the same plant. It is hypothesized that high nocturnal release of CO2 may guide the sand flies to rich sugar sources. Comparisons of Ph. papatasi feeding on branches of different plant species demonstrate a significant positive correlation between the level of sugar in leaves, the rate of sand fly feeding on them and the size of ingested sugar meals. Mean nocturnal CO2 emanation of low-sugar Ricinus communis branches is 26.5 ppm and that of sugar rich branches is 86.3 ppm above room level. Low-sugar Capparis spinosa branches release 45.0 ppm and the emission from sugar rich branches is 76.0 ppm above room level. Branches with similar emissions, placed behind net partitions, are used in no-choice orientation experiments: R. communis branches releasing high CO2 levels are approached by 53.7% of the flies compared with 3.0% of flies that orientate to low CO2 branches. Capparis spinosa with high CO2 emission are approached by 9.8% of the flies compared with 0.95% of flies that orientate to low CO2 branches.

Parasitology, 2002

Phlebotomus papatasi sand flies, the vectors of Leishmania major, differ genetically in their sus... more Phlebotomus papatasi sand flies, the vectors of Leishmania major, differ genetically in their susceptibility to the pathogens. The costs of infection appear to be so great that selection against Leishmania-susceptible flies could presumably occur, unless susceptibility is compensated for by some advantage. Foci of P. papatasi-transmitted L. major are mainly found in arid habitats where seasonal stress of dehydration and heat reduces the quantity of sugar in plant leaves. The sand flies feed on these leaves and with the lack of essential sugar only a few survive long enough to deposit eggs and transmit Leishmania. This association suggested that susceptibility to L. major infection may be linked with advantageous tolerance of sugar deprivation. Here we show that desert sand flies, provided with excess sugar, became progressively resistant to infection. Selection for survival under sugar-poor conditions increased the susceptibility of parent and first-generation offspring by more than 2-fold. The leaves of plants, on which flies naturally feed, contain more sugar in irrigated than in arid habitats. About 85% of first-generation flies colonized from a desert habitat retain experimental Leishmania infection compared to 25 % of offspring of flies from irrigated sites.

Nature, 2001

ABSTRACT The sandfly Phlebotomus papatasi transmits Leishmania major, the agent of cutaneous leis... more ABSTRACT The sandfly Phlebotomus papatasi transmits Leishmania major, the agent of cutaneous leishmaniasis, in desert and savannah regions of the Old World1, where seasonal stress of dehydration and heat reduces the quantity of sugar in plant leaves2. Without essential sugar, only a few flies that feed on leaves can survive for long enough to deposit eggs and transmit Leishmania3, 4. Accordingly, selection for hunger tolerance may also select for pathogen susceptibility in flies. Here we provide evidence of a link between these advantageous and costly5, 6 properties by testing the susceptibility of flies selected by sugar deprivation and of flies from irrigated and arid habitats.

Medical Microbiology and Immunology, 2001

This is a summary of the recent work on some glycosidases of sand¯ies and their Leishmania parasi... more This is a summary of the recent work on some glycosidases of sand¯ies and their Leishmania parasites. Glycosidases catalyze the hydrolysis of complex sugar subunits of polysaccharides into simple sugars. Leishmania major parasites secrete chitinase and N-acetylglucosaminase, which enables them to survive in the gut of the sand¯y and are important in facilitating their transmission by the phlebotomine sand¯y Phlebotomus papatasi. These enzymes are found in a wide range of trypanosomatids and the gene locus is highly conserved. The sand¯ies feed on plants and the ingested tissues may contain cellulose particles that the sand¯ies are unable to digest. Cellulolytic enzymes are secreted by L. major promastigotes and this may help to break down cellulose in infected¯ies and sustain their growth. Starch is a main photosynthesis product that is stored in leaves. Starch grains have been found in the midguts of ®eld caught sand¯ies and a-amylase, the speci®c enzyme for starch, has been found in the salivary glands and other organs of Lutzomyia longipalpis and P. papatasi. a-Amylase and a-glucosidase are expressed by L. major promastigotes and a-glucosidase is secreted by several trypanosomatid genera, but not by all those examined. Primers originally designed to amplify P. papatasi amylase DNA sequences, by polymerase chain reaction (PCR), also ampli®ed DNA from all Old World Leishmania species, indicating that the gene is highly conserved between sand¯ies and these parasites.

Medical and Veterinary Entomology, 1990

Stimuli which modulate oviposition of P. papatasi were investigated to improve insectary breeding... more Stimuli which modulate oviposition of P. papatasi were investigated to improve insectary breeding efficiency. Oviposition and survival of gravid females were observed weekly during April-December 1987, in plastic cages at 28 +/- 1 degrees C with L:D 17:7. Oviposition of controls was subject to seasonal variation despite the relatively uniform insectary conditions. From April to mid-October (summer), mean weekly oviposition ranged from 11.6 to 18.6 eggs per fly, dropping to 1.4 eggs/fly in November (winter). Monthly yields of eggs were found to correlate with the seasonal cycle of ultraviolet (UV) radiation in sunlight. This was attributed to an endogenous rhythm since the flies were not normally exposed to UV under insectary conditions. Short exposure to UV sources of 254 nm and 312 nm, but not white light, raised the low rate of oviposition in October-November from 1.4 to 16.8-29.6 eggs/female/week, but female mortality also increased highly significantly. It is suggested that the seasonal oviposition cycle of P.papatasi is set by levels of UV irradiation. In the warm season oviposition was promoted, as compared to controls, by furrows in plaster of Paris lining the bottom of cages (29.6 v. 10.2 eggs/female) and by cow manure in the cages (39.7 v. 18.2 eggs/female), but the combination of both stimuli gave no greater fecundity (40.9 v. 20.9 eggs/female). Oviposition decreased when larvae were present (3.9 v. 15.0 eggs/female) and in half-volume cages (3.9 v. 12.5 eggs/female/week). Under standard insectary conditions, mean weekly mortality-rates of P.papatasi females were 18.3 +/- 4.8% in October-November and 36.5-59.1% during the warmer months. None of the experimental conditions yielded any significant improvement in survival-rates.

Medical and Veterinary Entomology, 1999

The sugar diet and life-span of Phlebotomus papatasi were studied in a typical zoonotic focus of ... more The sugar diet and life-span of Phlebotomus papatasi were studied in a typical zoonotic focus of Leishmania major in an arid area of the Jordan Valley during 1996±1997. Plant-tissue residues (cellulose particles) were identi®ed in the stained guts of 23% of P. papatasi and signi®cant amounts of sugar were found in the gut of 16%. Feeding on different plants was demonstrated by using their branches, suffused with cellulose stain, as baits in the ®eld. Ingested, stained cellulose was detected in 10% of the sand¯ies (6% of males, 12.5% of females) caught near bait-branches of common local plants, mostly Chenopodiaceae. The similar rates of plant and sugar feeding, with the observed absence of aphids (ruling out the availability of honeydew), implied that the sugar meals of sand¯ies were obtained directly from plants.