Adult Opisthorchis viverrini Flukes in Humans, Takeo, Cambodia

(1). Sophisticated laboratory methods, although sensitive, are costly. The immunochromatographic strip test that uses recombinant K39 antigen (rK39), although satisfactory in India, is less sensitive in Africa, Latin America, and Mediterranean regions (2). Post–kala-azar dermal leishmaniasis (PKDL), a sequel to VL in India and Africa, is often confused with other skin diseases (3,4). Diagnosis of VL in dogs in Latin America and Mediterranean countries remains confusing because of rampant asymptomatic infections and elevated antibodies against Leishmania spp. (5)

Discovery of Markers of Exposure Specific to Bites of Lutzomyia longipalpis, the Vector of Leishmania infantum chagasi in Latin America

Leishmania parasites are transmitted by the bite of an infected vector sand fly that injects salivary molecules into the host skin during feeding. Certain salivary molecules can produce antibodies and can be used as an indicator of exposure to a vector sand fly and potentially the disease it transmits. Here we identified potential markers of specific exposure to the sand fly Lutzomyia longipalpis, the vector of visceral leishmaniasis in Latin America. Initially, we determined which of the salivary proteins produce antibodies in humans, dogs, and foxes from areas endemic for the disease. To identify potential specific markers of vector exposure, we produced nine different recombinant salivary proteins from Lu. longipalpis and tested for their recognition by individuals exposed to another human-biting sand fly, Lu. intermedia, that transmits cutaneous leishmaniasis and commonly occurs in the same endemic areas as Lu. longipalpis. Two of the nine salivary proteins were recognized only by humans exposed to Lu. longipalpis, suggesting they are immunogenic proteins and may be useful in epidemiological studies. The identification of specific salivary proteins as potential markers of exposure to vector sand flies will increase our understanding of vector–human interaction, bring new insights to vector control, and in some instances act as an indicator for risk of acquiring disease

Detection of the recombinant salivary proteins LJM17 and LJM11 by human sera from endemic areas.

<p>Western Blot with LJM17 or LJM11 recombinant proteins were screened with sera from humans in Canoa where <i>Lutzomyia intermedia</i> predominates ( Human – CL endemic area) or with sera from São Luis area where <i>Lu. longipalpis</i> predominates (Human – VL endemic area). Sera from individuals from a non-endemic area were used as negative controls (CTL–).</p

Total IgG response in dogs from endemic areas and dogs experimentally exposed to <i>Lutzomyia longipalpis</i> bites.

<p>Dog sera from Teresina, an area endemic for visceral leishmaniasis where <i>Lu. longipalpis</i> predominates, (Dog-VL endemic area) and sera from dogs experimentally exposed to <i>Lu. longipalpis</i> bites (Dog – Experimentally exposed) were screened against salivary proteins from <i>Lu. longipalpis</i> (LL), <i>Lu. intermedia</i> (LI), <i>Lu. verrucarum</i> (LV), and <i>Phlebotomus perniciosus</i> (PPe) by Western Blot.</p

Transcripts selected from a <i>Lutzomyia longipalpis</i> salivary gland cDNA library based on predicted molecular weight of secreted proteins.

<p>Transcripts selected from a <i>Lutzomyia longipalpis</i> salivary gland cDNA library based on predicted molecular weight of secreted proteins.</p

Production of recombinant sand fly salivary proteins.

<p><i>A</i>, Flowchart describing the expression, purification and detection of recombinant sand fly salivary proteins from <i>Lutzomyia longipalpis</i>. <i>B</i>, Chromatogram of the purification of the LJM17 recombinant protein by HPLC-metal affinity chromatography. <i>C</i>, Detection of positive fractions for the LJM17 recombinant protein using sera from mice immunized with LJM17 plasmid. <i>D</i>, Silver-stained SDS-PAGE of LJM17 recombinant protein before (1) and after (2) HPLC purification.</p

<i>Lutzomyia longipalpis</i> salivary proteins recognized by human, dog and fox sera from the visceral leishmaniasis endemic areas of São Luis and Teresina.

<p><i>A</i>, Silver staining of a Bis-Tris NuPAGE gel of salivary proteins from <i>Lu. longipalpis</i>. <i>B</i>, Western Blot of salivary proteins of <i>Lu. longipalpis</i> separated on a Tris-Glycine gel using a representative reactive sera from either human (São Luis), dog or fox (Teresina).</p

Detection of <i>Lutzomyia longipalpis</i> recombinant salivary proteins by human and dog sera from visceral leishmaniasis endemic areas.

<p>Human and dog sera from São Luis and Teresina respectively, were used to screen recombinant salivary proteins LJM17, LJM11, LJM111, LJL13, LJL23, LJM04, and LJL143 by Western Blot (+). Human and dog sera from a non-endemic area were used as negative controls (–).</p