ABSTRACT. Several species of birds in Minami Daito Island, an oceanic island located in the far south from the main islands of Japan, were found to be infected with avian Plasmodium. However, no vector species of the avian malaria in this island have been revealed yet. To speculate potential vectors, we collected mosquitoes there and investigated using a PCR procedure whether the mosquitoes harbor avian malaria or not. Totally 1,264 mosquitoes including 9 species were collected during March 2006 to February 2007. The mosquitoes collected were stored every species, sampled date and location for DNA extraction. Fifteen out of 399 DNA samples showed positive for the partial mtDNA cytb gene of avian Plasmodium. Estimated minimum infection rate among collected mosquitoes was 1.2% in this study. Four species of mosquitoes; Aedes albopictus, Culex quinquefasciatus, Lutzia fuscanus and Mansonia sp. had avian Plasmodium gene sequences. Detected DNA sequences from A. albopictus and L. fuscanus were identical to an avian Plasmodium lineage detected in bull-headed shrike (Lanius bucephalus) captured in the island. Different sequences were detected from C. quinquefasciatus, which were corresponding to an avian Plasmodium from a sparrow (Passer montanus) and Plasmodium gallinaceum. Our results suggest that A. albopictus, Lutzia fuscanus, C. quinquefasciatus, and Mansonia sp. could be potential vectors of avian malaria in Minami Daito Island. This study was the first report of molecular detection of avian Plasmodium from mosquitoes in Japan.
Several species of captive birds at zoological gardens of Japan were found to be infected with avian Plasmodium. However, incriminated vector mosquito species have not been identified yet. To indicate the competent vectors of avian malaria parasite, we collected mosquitoes at a zoological garden in Japan and examined for the avian malaria parasite DNA. Totally, 1,361 mosquitoes of 11 species were collected in the zoological garden of Kanagawa, the south of Tokyo in Japan in 2005. Captured mosquitoes were pooled by each species, date collected, and location and used for DNA extraction. Eight out of 169 DNA samples were positive for the nested PCR of avian Plasmodium cyt b gene. Estimated minimum infection rates of mosquitoes were 5.9 per 1,000. The PCR positive mosquito species were Culex pipiens group and Lutzia vorax. Some DNA sequences amplified from collected mosquitoes were identical to avian Plasmodium lineages detected from captive birds in the same zoological garden studied. Our results suggest that C. pipiens group and L. vorax could be incriminated vectors of avian malaria parasite transmitting in captive birds kept in the zoological garden in Japan.
We analyzed mitochondrial genomes of two avian malaria protozoa, Plasmodium gallinaceum and Plasmodium juxtanucleare. Both mitochondrial genomes were estimated to be 6,002 and 6,014 bp in length, respectively, and to have the identical gene organization and contents to that of other Plasmodium species previously analyzed; three functional genes for cytochrome c oxidase subunit I, III, and cytochrome (cyt b), with following sets of discontinuous and scrambled 15 ribosomal subunit RNA (rRNA) genes. Similarities of the three protein-coding genes showed closer relationship within avian malaria protozoa rather than mammalian Plasmodium species. In addition, we showed the tandem repeated structure of each mitochondrial genome of both P. gallinaceum and P. juxtanucleare as well as previously found in mammalian Plasmodium species. This study revealed the complete sequences and structure of the mitochondrial genomes of avian malaria protozoa for the first time.
We analyzed extra chromosomal genomes of avian blood protozoa, Leucocytozoon caulleryi. One of the genomes, the mitochondrial genome was completely sequenced resulting 5,959 bp in length. This genome contained the identical gene organization and contents to that of other avian blood protozoa previously analyzed: three functional genes for cytochrome c oxidase subunit I, III, and cytochrome b with following sets of discontinuous and scrambled 15 ribosomal subunit RNA genes. In addition, the mitochondrial genome was estimated to have the tandem repeated structure as well as previously found in avian Plasmodium species. Furthermore, we found partial gene sequences of apicoplast DNA, another extra chromosomal genome, from L. caulleryi. These sequences were estimated as partial caseinolytic protease C and elongation factor Tu A genes. This report is the first description of two extra chromosomal genomes of L. caulleryi.
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