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BACTERIAL FEEDING, LEISHMANIA INFECTION AND DISTINCT INFECTION ROUTES INDUCE DIFFERENTIAL DEFENSIN EXPRESSION IN LUTZOMYIA LONGIPALPIS
Autor
Afiliación
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular de Parasitos e Vetores. Rio de Janeiro, RJ, Brasil / Liverpool School of Tropical Medicine. Vector Group. Liverpool, England, UK.
Lancaster University. School of Health and Medicine. Lancaster, England, UK.
Liverpool School of Tropical Medicine. Vector Group. Liverpool, England, UK.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular de Parasitos e Vetores. Rio de Janeiro, RJ, Brasil.
Lancaster University. School of Health and Medicine. Lancaster, England, UK.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular de Parasitos e Vetores. Rio de Janeiro, RJ, Brasil.
Lancaster University. School of Health and Medicine. Lancaster, England, UK.
Liverpool School of Tropical Medicine. Vector Group. Liverpool, England, UK.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular de Parasitos e Vetores. Rio de Janeiro, RJ, Brasil.
Lancaster University. School of Health and Medicine. Lancaster, England, UK.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Molecular de Parasitos e Vetores. Rio de Janeiro, RJ, Brasil.
Resumen en ingles
Background: Phlebotomine insects harbor bacterial, viral and parasitic pathogens that can cause diseases of public
health importance. Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the New World. Insects can
mount a powerful innate immune response to pathogens. Defensin peptides take part in this response and are
known to be active against Gram-positive and Gram-negative bacteria, and some parasites. We studied the
expression of a defensin gene from Lutzomyia longipalpis to understand its role in sand fly immune response.
Methods: We identified, sequenced and evaluated the expression of a L. longipalpis defensin gene by
semi-quantitative RT-PCR. The gene sequence was compared to other vectors defensins and expression was
determined along developmental stages and after exposure of adult female L. longipalpis to bacteria and
Leishmania.
Results: Phylogenetic analysis showed that the L. longipalpis defensin is closely related to a defensin from the Old
World sand fly Phlebotomus duboscqi. Expression was high in late L4 larvae and pupae in comparison to early larval
stages and newly emerged flies. Defensin expression was modulated by oral infection with bacteria. The
Gram-positive Micrococcus luteus induced early high defensin expression, whilst the Gram-negative
entomopathogenic Serratia marcescens induced a later response. Bacterial injection also induced defensin
expression in adult insects. Female sand flies infected orally with Leishmania mexicana showed no significant
difference in defensin expression compared to blood fed insects apart from a lower defensin expression 5 days
post Leishmania infection. When Leishmania was introduced into the hemolymph by injection there was no
induction of defensin expression until 72 h later.
Conclusions: Our results suggest that L. longipalpis modulates defensin expression upon bacterial and Leishmania
infection, with patterns of expression that are distinct among bacterial species and routes of infection.
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