Loma salmonae is a common gill parasite of salmonids, and essentially all species in the genus Oncorhynchus are susceptible. Infections occur in both fresh and salt water. Loma salmonae is directly transmissible by ingestion of spores or infected tissue. The parasite infects the wall of blood vessels of various organs, but the gill is the primary site of infection. Initial infection occurs in the intestine, and xenomas are easily detected in the gills by standard histology at 4-6 wk post-exposure. A few presporogonic stages of the parasite are found in the heart endothelium prior to xenoma formation in the gills. Ultrastructure studies of early infections demonstrated that wandering blood cells transport the meronts to the gills, and that merogony occurs in pillar cells and other cells underlying the gill endothelium. Xenomas develop in these cells, resulting in hypertrophied host cells filled with spores. Xenomas ultimately rupture, and are associated with severe inflammation in which free spores are found in macrophages. The parasites are most pathogenic during this phase of the infection, resulting in severe vasculitis and clinical disease. Both rainbow trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus ishawytscha) recover from infections, but free spores persist in kidney and spleen phagocytes for many months after xenomas are absent in Chinook salmon. Fish that have recovered from the infection show strong immunity against the parasite, lasting up to 1 year. Fish are susceptible to infection by other routes of exposure by spores; co-habitation, anal gavage, and intramuscular, intraperitoneal and intravascular injection. Autoinfection probably occurs following release of spores in blood vessels after xenomas rupture. The optimal temperature for L. salmonae infections is 15-17 degrees C, with a permissive range of 11-20 degrees C.
- MeSH
- cévy mikrobiologie MeSH
- losos * MeSH
- Microsporida růst a vývoj patogenita ultrastruktura MeSH
- mikrosporidióza imunologie přenos veterinární MeSH
- nemoci ryb imunologie mikrobiologie MeSH
- obrovské buňky mikrobiologie MeSH
- Oncorhynchus mykiss * MeSH
- spory hub fyziologie MeSH
- stadia vývoje fyziologie MeSH
- střeva mikrobiologie MeSH
- transmisní elektronová mikroskopie MeSH
- žábry mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The epizootiology, transmission dynamics, and survival strategies employed by two mosquito-parasitic microsporidia that utilize copepods as intermediate hosts are examined in relation to the biological attributes of their hosts and the environments in which they inhabit. Amblyospora connecticus Andreadis, 1988, a parasite of Ochlerotatus cantator (Coquillett) and Acanthocyclops vernalis (Fischer) is found in an unstable salt marsh environment that is subject to periodic flooding and drying. Both hosts have distinct non-overlapping generations. A. connecticus exhibits a well-defined seasonal transmission cycle that relies heavily on maternal-mediated transovarial transmission by female O. cantator during the summer, and horizontal transmission via the copepod host during the spring (copepod to mosquito) and fall (mosquito to copepod). Its survival strategies include: delayed virulence, low pathogenicity and high tissue specificity that allow for transstadial transmission of horizontally acquired infections and maximum spore production, reliance on living hosts throughout most of its life cycle with overwintering in the copepod, polymorphic development that is well synchronized with host physiology, and production and dissemination of infectious spores that are coincident with the seasonal occurrence of susceptible stages in each host. Hyalinocysta chapmani Hazard et Oldacre, 1975, a parasite of Culiseta melanura (Coquillett) and Orthocyclops modestus (Herrick) is found in a comparatively stable, subterranean habitat that is inundated with water throughout the year. Copepods are omnipresent and C. melanura has overlapping broods. H. chapmani is maintained in a continuous cycle of horizontal transmission between each host throughout the summer and fall but lacks a developmental sequence leading to transovarial transmission in the mosquito host. It relies on living hosts for most of its life cycle and overwinters in diapausing mosquito larvae. Transstadial transmission does not occur and there is no dimorphic development in the mosquito host. The spatial and temporal overlap of both mosquito and copepod hosts during the summer and fall affords abundant opportunity for continuous horizontal transmission and increases the likelihood that H. chapmani will find a target host, thus negating the need for a transovarial route. It is hypothesized that natural selection has favoured the production of meiospores in larval female mosquitoes rather than congenital transfer of infection to progeny via ovarian infection as a strategy for achieving greater transmission success. Analysis of the molecular phylogeny data suggest that (1) transovarial transmission and the developmental sequence leading to ovarian infection have been secondarily lost in H. chapmani, as they occur in all other closely related genera, (2) the ancestral state included complex life cycles involving transovarial transmission and an intermediate host, and (3) mosquito-parasitic microsporidia are adjusting their life cycles to accommodate host ecological conditions.
- MeSH
- biologická adaptace fyziologie MeSH
- biologická evoluce * MeSH
- Copepoda mikrobiologie MeSH
- Culicidae mikrobiologie MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- interakce hostitele a parazita MeSH
- Microsporida růst a vývoj fyziologie MeSH
- ovum mikrobiologie MeSH
- roční období MeSH
- stadia vývoje fyziologie MeSH
- životní prostředí * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Ocular, peroral, intraperitoneal, intramuscular, and subcutaneous inoculation of severe combined immunodeficient (SCID) mice with spores of the human isolate (CDC: V404) of Brachiola algerae (syn. Nosema algerae) (Phylum Microspora) revealed that the microsporidium develops in viscera of the immunodeficient mouse host, but only after the ocular administration of spores. It is hypothesized that the physico-chemical milieu of the conjunctiva and cornea helped to adapt the originally 'poikilothermic microsporidian' to the conditions within the homoiothermic organism. Ocular application of spores caused no clinical signs of disease at the application site. However, severe infection in the liver was found 60 days after infection, manifested as hepatosplenomegaly and multifocal miliary necroses and granulomas containing parasites. No microsporidia were found in any other tissues. Transmission electron microscopy revealed characteristic tubulovesicular 'secretory materials' on the plasma membrane of all developmental stages of B. algerae except sporoblasts and spores. These formations increase the parasite surface and allow more efficient metabolic communication of the parasite with the host cell. It is hypothesized that the presence of these structures is a factor helping the parasite to grow in a variety of hosts and tissues. Ultrastructural characters support the likelihood that B. algerae and B. vesicularum are conspecific, and that there exists a relationship between species of the genera Brachiola and Anncaliia.
- MeSH
- elektronová mikroskopie MeSH
- hepatomegalie parazitologie patologie MeSH
- interakce hostitele a parazita MeSH
- játra parazitologie patologie ultrastruktura MeSH
- lidé MeSH
- Microsporida růst a vývoj izolace a purifikace ultrastruktura MeSH
- mikrosporidióza parazitologie patologie MeSH
- myši SCID MeSH
- myši MeSH
- senioři MeSH
- splenomegalie parazitologie patologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- senioři MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Trachipleistophora anthropophthera n. sp., was found at autopsy in the brain of one and in the brain, kidneys, pancreas, thyroid, parathyroid, heart, liver, spleen, lymph nodes, and bone marrow of a second patient with AIDS. The parasite is similar to the recently described T. hominis Hollister, Canning, Weidner, Field, Kench and Marriott, 1996, in having isolated nuclei, meronts with a thick layer of electron dense material on the outer face of their plasmalemma and sporogony during which spores are formed inside a thick-walled sporophorous vesicle. In contrast to T. hominis, this species is dimorphic as it forms two kinds of sporophorous vesicles and spores: Type I--round to oval polysporous sporophorous vesicle, 7-10 microns in size, usually with eight spores (3.7 x 2.0 microns), thick endospores, subterminal anchoring disc and anisofilar polar filaments forming seven thicker and two thinner terminal coils. This type of sporophorous vesicle is associated with 25-30 nm filaments extending into the host cell cytoplasm. Type II--smaller, bisporous sporophorous vesicle (4-5 x 2.2-2.5 microns) with two, nearly round, thin-walled spores, 2.2-2.5 x 1.8-2.0 microns in size, having 4-5 isofilar coils. No outside filamentous elements are associated with the bisporous sporophorous vesicle. Both types of sporophorous vesicles were common in the infected brain tissue and could be found within the same cell. The newly described species, together with T. hominis and previously reported Pleistophora-like parasites from human muscle, likely represent a group of closely related human microsporidia.
- MeSH
- elektronová mikroskopie MeSH
- ledviny parazitologie MeSH
- lidé MeSH
- Microsporida klasifikace růst a vývoj izolace a purifikace ultrastruktura MeSH
- mikroskopie elektronová rastrovací MeSH
- mikrosporidióza parazitologie patologie MeSH
- mozek parazitologie MeSH
- oportunní infekce doprovázející AIDS parazitologie patologie MeSH
- spory ultrastruktura MeSH
- srdce parazitologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
When in vitro growth of Vittaforma corneae was tested using MDCK, MRC-5, XEN, L-929 and FHM cell lines, propagation occurred only in MDCK, MRC-5 and XEN cells. The intervals required for the various stages of the life cycle to develop were the same in all the cell lines tested. The MDCK cell line was selected to support the growth of V. corneae in vitro and provide the system for in vitro testing of drugs. The weekly output of V. corneae spores from the MDCK cell monolayer was monitored over a 61-week period during which there were fluctuations but no definite increase or decrease in output. Albendazole at 2.1 or 4.2 micrograms/ml in MEM was tested against V. corneae in MDCK cell monolayers and showed antimicrosporidial activity. The percentage of infected cells was reduced in the presence of the drug and there were ultrastructural abnormalities in all stages of the life cycle. The drug prevents parasite division.
- MeSH
- albendazol farmakologie MeSH
- anthelmintika farmakologie MeSH
- buněčné linie MeSH
- fibroblasty MeSH
- ledviny MeSH
- lidé MeSH
- Microsporida účinky léků růst a vývoj ultrastruktura MeSH
- Nosema účinky léků růst a vývoj ultrastruktura MeSH
- plíce embryologie MeSH
- psi MeSH
- spory MeSH
- Xenopus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- psi MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- albendazol MeSH
- anthelmintika MeSH
Heterosporous (polymorphic) microsporidia in mosquitoes are characterized by intricate life cycles involving multiple spore types responsible for horizontal (per os) and vertical (transovarial) transmission. They affect two generations of the mosquito and some involve an obligate intermediate host. Heterosporous microsporidia are generally very host and tissue specific with complex developmental sequences comprised of unique stages and events. Full details on the intricate relationships between heterosporous microsporidia and their mosquito hosts have only recently been elucidated. Edhazardia aedis (Kudo, 1930) and Culicospora magna (Kudo, 1920) have developmental sequences in larvae that involve gametogony followed by plasmogamy and nuclear association to form diplokarya. These diplokaryotic stages then undergo karyogamy and form binucleate spores responsible for transovarial transmission. In the filial generation, haplosis occurs as a result of nuclear dissociation to produce uninucleate spores infectious to larval mosquitoes. Amblyospora californica (Kellen et Lipa, 1960) has similar sequences except that haplosis is by meiosis to produce spores infectious for a copepod intermediate host. A third spore type is formed in the intermediate host responsible for infection in a new generation of the mosquito host.
- MeSH
- Encephalitozoon růst a vývoj MeSH
- encephalitozoonóza komplikace MeSH
- lidé MeSH
- Microsporida růst a vývoj MeSH
- mikrosporidióza komplikace MeSH
- oportunní infekce doprovázející AIDS parazitologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
