Trypsin and chymotrypsin-like enzymes of the sandfly Phlebotomus papatasi infected with Leishmania and their possible role in vector competence.
Phlebotomus papatasi (Scopoli) is susceptible to infection with Leishmania major Yakimov & Schokov and resistant to L. donovani Laveran & Mesnil. The possibility that susceptibility depends on midgut levels of trypsin and chymotrypsin-like (esterolytic) enzymes was investigated. Infection with L. major reduced the trypsin-like activity to 93.5% and 86% of the control value at 20 and 30 h post feeding and increased it to 106% at 52 h. Infection with L. donovani reduced trypsin-like activity to 64% and 73% of the control value at 30 and 52 h post feeding. The overall amount of trypsin and chymotrypsin-like enzymes in L. major infections was reduced to 50% and 34% of the control value at 20 and 30 h post feeding and increased to 184% at 52 h. Only one of the enzymes separated by gel electrophoresis was lower throughout, i.e. peak D. Overall, the midgut enzyme level with L. donovani infection was 86% of the control value at 30 h post feeding and 105% at 52 h; their relative amounts changed throughout. Soybean trypsin inhibitor enabled L. donovani to survive and multiply in P. papatasi. It is suggested that a specific component of the trypsin-like activity prevents the survival of L. donovani in P. papatasi and that modulation of this factor enables L. major to survive.
Borovsky
D
D
University of Florida, IFAS, Florida Medical Entomology Laboratory, Vero Beach 32962.
Schlein
Y
Y
D000818:Animals; D002918:Chymotrypsin / Q000032:analysis*; D007303:Insect Vectors / Q000201:enzymology / Q000469:parasitology*; D007891:Leishmania / Q000502:physiology*; D007893:Leishmania donovani / Q000502:physiology; D007895:Leishmania tropica / Q000502:physiology; D010691:Phlebotomus / Q000201:enzymology / Q000469:parasitology*; D014357:Trypsin / Q000032:analysis*
D002918:Chymotrypsin; D014357:Trypsin