Serovar diversity of Leptospira sp. infecting wild rodents in Sarawak, Malaysia

Leptopsirosis is a zoonotic disease with global distribution and rodents, in particular rats, have been identified as the main reservoir host. A study was conducted to determine the prevalence of antibodies against Leptospira sp. in wild rodents caught in selected areas of Sibu, Sarikei and Kapit in Sarawak during the period of July 2011 to May 2014. In total, 241 sera samples were collected from rodents caught from these three administrative divisions in Sarawak. Ninety-eight rodents (40.7%) were positive with antibody titre >1:50 by microscopic agglutination test (MAT) against 13 out of 20 common local leptospiral serovars tested. Sera of rodents caught in Sibu, Kapit and Sarikei divisions were positive at 43.9%, 37.5% and 36.4%, respectively. The top five serovars detected were: Autumnalis (25.5%), Tarassovi (23.5%), Bataviae (15.3%), Hebdomadis (8.2%) and Celledoni (7.2%). The main species of rodent positive for antibodies against Leptopsira sp. were Sundamys muelleri (50.0%), Rattus rattus (37.5%), Callociurus notatus (35.6%) and Rattus exulans (32.6%). This study indicates that leptospiral antibodies are prevalent amongst wild rodents in central Sarawak, which could be translated as high leptospiral carriage. The close interaction that exists between the local community and the environment could potentially propagate the transmission of Leptospira sp. to human in these areas. This study also provided essential information about local circulating Leptospira serovars, which could be useful for eventual prevention measures in disease transmissio

Tissue polyunsaturated fatty acids and a digestive phospholipase A \u3csub\u3e3\u3c/sub\u3e in the primary screwworm, \u3ci\u3eCochliomyia hominivorax\u3c/i\u3e

We report on the presence of arachidonic acid in larval and adult tissues of the primary screwworm, Cochliomyia hominivorax and of the secondary screwworm, C. macellaria. Arachidonic acid is present in the phospholipids of whole animal extracts of both species. This fatty acid appears to be accumulated during the larval stages, because proportions of arachidonic acid were higher in adults than in larvae. These insects probably obtain the arachidonic acid from dietary phospholipids. We also report on a phospholipase A2 activity in midgut preparations from third instars of the primary screwworm. Phospholipase A2 is responsible for hydrolyzing fatty acids from the sn-2 position of dietary phospholipids to release essential fatty acids. The screwworm enzyme is similar to mammalian digestive phospholipase A2s because it depends on calcium for high catalytic activity, it is sensitive to the sitespecific inhibitor oleyloxyethylphosphorylcholine, and it interacts with heparin. We further characterized the screwworm midgut phospholipase A2 by altering the reaction conditions, including reaction time, radioactive substrate concentration, protein concentration, pH and temperature. We speculate that the biological significance of this enzyme relates to acquiring essential fatty acids, including arachidonic acid, from dietary phospholipids. &#;&#;1999 Elsevier Science Ltd. All rights reserved

Eicosanoids in insect immunity: Bacterial infection stimulates hemocytic phospholipase A(2) activity in tobacco hornworms

WOS: 000180202600001PubMed: 12489129Intracellular phospholipase A(2) (PLA(2)) is responsible for releasing arachidonic acid from cellular phospholipids, and is thought to be the first step in eicosanoid biosynthesis. Intracellular PLA(2)s have been characterized in fat body and hemocytes from tobacco hornworms, Manduco sexta. here we show that bacterial challenge stimulated increased PLA(2) activity in isolated hemocyte preparations, relative to control hemocyte preparations that were challenged with water. The increased activity was detected as early as 15 s post-challenge and lasted for at least 1 h. The increased activity depended on a minimum bacterial challenge dose, and was inhibited in reactions conducted in the presence of oleyoxyethylphosphorylcholine, a site-specific PLA(2) inhibitor. In independent experiments with serum prepared from whole hemolymph, we found no PLA(2) activity was secreted into serum during the first 24 h following bacterial infection. We infer that a hemocytic intracellular PLA(2) activity is increased immediately an infection is detected. The significance of this enzyme lies in its role in launching the biosynthesis of eicosanoids, which mediate cellular immune reactions to bacterial infection