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PubMed2005

Regional distribution of Paenibacillus larvae subspecies larvae, the causative organism of American foulbrood, in honey bee colonies of the Western United States.

We examined honey bee, Apis mellifera L., colonies pollinating almonds in California during February 2003 for Paenibacillus larvae subsp. Larvae, the causative organism of the virulent brood disease American foulbrood. Colonies originating from the Rocky Mountain area and California had significantly higher numbers (P < 0.05) of bacterial colony-forming units (CFUs) (408 and 324 per 30 adult bees, respectively) than colonies from the upper Midwest (1.28). Colonies from the northwestern, central, and southwestern United States had intermediate CFU or bacterial colony levels. Operations positive for P. larvae larvae were relatively uniform at approximately 70-80%, and no regional significant differences were found. Percentages of colonies with high CFUs (> or = 400 per 30 bees) differed significantly, with those from the Rocky Mountain region having 8.73% compared with those of the upper Midwest with 0%. The significance of CFU levels was evaluated by inoculating healthy colonies with diseased immatures and sampling adult bees. The number of CFUs detected per diseased immature was conservatively estimated to be approximately 399 CFUs per 30 adult bees. We defined this spore level as 1 disease equivalent. Based on this, 3.86% colonies in our survey had 1 or more disease equivalent number of P. larvae larvae CFUs. Operations with high P. larvae larvae spore levels in their colonies will likely observe American foulbrood if prophylaxis is not practiced diligently.

Animals↗
PubMed1984

Raccoon ascarid larvae (Baylisascaris procyonis) as a cause of ocular larva migrans.

Larvae of the common raccoon roundworm, Baylisascaris procyonis, are known causes of visceral larva migrans and CNS disease in animals and human beings. In the present experiments we examined the ability of B. procyonis to cause ocular larva migrans (OLM) in subhuman primates, as an indication of its possible ocular zoonotic importance. Squirrel monkeys given 5,000 or 10,000 infective B. procyonis eggs per os and cynomolgus monkeys given 20,000 eggs had clinical and histologic evidence of OLM, beginning 7 days after inoculation. Clinically, multifocal retinal hemorrhages, white spots, chorioretinitis, inflammatory tracks, vascular sheathing, diffuse retinal degeneration, and motile intraretinal larvae were seen. Histologically, primarily subretinal larvae caused varying degrees of retinal disruption, degeneration and necrosis, retinitis, vasculitis, and perivascular sheathing, primarily with eosinophils. Larvae were also present in choroidal granulomas. It was concluded that B. procyonis larvae have marked ability to produce OLM in subhuman primates following oral infection and should be considered as a possible etiology in human ocular disease.

Animals↗
PubMed2005

Developmental arrest in Caenorhabditis elegans dauer larvae causes high expression of enzymes involved in thymidylate biosynthesis, similar to that found in Trichinella muscle larvae.

Crude extract specific activities of thymidylate synthase, dUTPase, thymidine kinase and dihydrofolate reductase were high during the development of Caenorhabditis elegans, the dauer larva activities being similar to those previously determined in Trichinella spiralis and T. pseudospiralis muscle larvae (with the exception of thymidine kinase, not detected in Trichinella). High thymidylate synthase expression in developmentally arrested larvae, demonstrated also at the mRNA and protein levels, is in agreement with a global cell cycle arrest of dauer larvae and indicates this unusual cell cycle regulation pattern can be shared by developmentally arrested larvae of C. elegans and the two Trichnella species. Hence, the phenomenon may be characteristic for developmentally arrested larvae of different nematodes, rather than specific for the parasitic Trichinella muscle larvae. Endogenous C. elegans thymidylate synthase was purified and its molecular properties compared with those of the recombinant protein, expression of the latter in E. coli cells confirming the NCBI database sequence identity.

Animals↗
PubMed2003

Larvae and early post-larvae of Penaeus monodon (Fabricius) experimentally infected with white spot syndrome virus (WSSV) show no significant mortality.

The pathogenicity of white spot syndrome virus (WSSV) was tested with different developmental stages of Penaeus monodon, i.e. nauplius, protozoeae, mysis, early post-larvae (PL1-10), late post-larvae (PL11-20) and juveniles. WSSV challenge was done by immersion and oral routes. No disease occurred in the larvae and early post-larvae but they were positive for WSSV by nested polymerase chain reaction (PCR) assay. Significant mortality was observed in late post-larvae and juveniles and both single and nested PCR assays gave positive results with these samples. The results demonstrated that WSSV virulence in P. monodon increases with advancing stages of development and that WSSV infection does not result in disease for larvae and post-larvae younger than PL10.

Animals↗
PubMed1995

Antigens derived from lung-stage larvae of Schistosoma mansoni are efficient stimulators of proliferation and gamma interferon secretion by lymphocytes from mice vaccinated with attenuated larvae.

Protective immunity in C57BL/6 mice exposed to optimally irradiated larvae of Schistosoma mansoni operates against challenge parasites in the lungs and is dependent upon T-helper 1 (Th1) lymphocytes which secrete abundant gamma interferon (IFN-gamma). As an initial step in the identification of the molecules which mediate this immunity, antigenic materials released by larvae at various times during in vitro culture were compared for the ability to induce proliferation of lymph node cells recovered from mice 4 to 6 days after exposure to attenuated parasites. Cells from mice vaccinated with cercariae proliferated most strongly to larval antigens released soon after transformation. In contrast, cells from mice immunized with lung-stage schistosomula responded poorly to these early secretions but proliferated vigorously to antigens released by older larvae. In further studies on the cytokine profile of the responding lymphocytes, it was observed that the balance between IFN-gamma and interleukin-4 (IL-4) secretion depended on the source of antigen used for restimulation. Thus, material released between days 6 and 8 by in vitro-cultured larvae, and the soluble extracts of whole lung-stage larvae, induced abundant IFN-gamma but little IL-4. This finding implies that an overwhelming proportion of the lymphocytes responsive to lung-stage antigens had the Th1 phenotype. In contrast, antigens from cercariae and skin-stage larvae induced the lowest levels of IFN-gamma but higher levels of IL-4. It appears that a proportion of the cells with specificities for early antigens had the Th2 or Th0 phenotype. Our results emphasize that antigens from lung-stage larvae are an important source of potentially protective molecules.

Age Factors↗
PubMed1978

Associated changes in the size and number of mitochondria present in the midgut of the larvae of the housefly, Musca domestica and phospholipid composition of the larvae.

A possible relationship between the phospholipid base composition of larvae of the housefly and the size, number and total volume of midgut mitochondria was examined. The phospholipid composition of the larvae was altered by restricting the amount of choline, substituting choline by N-dimethylethyl-(2-hydroxyethyl)-ammonium salt or 2-N-dimethylaminoethanol and by the addition of 2-aminobutan-1-ol to the larval diet. Mitochondrial measurements were made on electron micrographs of the epithelial cells in the midgut of third instar larvae. Reduction in the normal proportion of phosphatidylcholine in the phospholipids of the larvae was associated with an increase in the average size of the mitochondria and a decrease in their number, probably due to enhanced mitochondrial fusion. The opposite effect was noted when phosphatidyl-2-aminobutan-1-ol was present as a part replacement of the phosphatidyl-ethanolamine normally present in the larvae. Larvae which contained both phosphatidyl-2-aminobutan-1-ol as well as reduced amounts of phosphatidylcholine, contained mitochondria which were intermediate in both size and number. The effects associated with the changes in phosphatidylcholine and phosphatidyl-2-aminobutan-1-ol were independent of each other. The presence of the analogue of phosphatidylcholine and phosphatidyldimethylaminoethanol had no significant effect on the mitochondrial distribution. Total mitochondrial volume remained unaffected by alterations in the phospholipid composition of the larvae.

Animals↗
PubMed1997

Survey for Gnathostoma nipponicum larvae in gobiid freshwater fish and infectivity of the larvae to a gobiid fish (Chaenogobius urotaenia).

From June 1993 to November 1996, a total of 977 gobiid fish consisting of three species (Tridentiger brevispinis, Chaenogobius urotaenia, and Rhinogobiu brunneus) collected from eastern Aomori Prefecture, were examined for Gnathostoma nipponicum larvae infection. Only one species, C. urotaenia was infected with advanced third-stage larvae (AdL3), and a total of 22 larvae were recovered from 17 (3.4%) of 500 fish. The infected fish were larger than 12 cm in body length and collected in the May-June and September-November seasons. Experimental studies confirmed that C. urotaenia was susceptible to both the early third-stage larvae (EaL3) obtained from Eucyclops serrulatus and AdL3 from Misgurnus anguillicaudatus. Eight of 10 C. urotaenia inoculated orally with 10 EaL3 were positive, and 36 AdL3 were recovered from them (recovery rate: 36.0%) at 30 days postinoculation (PI). All 10 C. urotaenia inoculated with 10 AdL3 were also positive, and a total of 63 AdL3 were recovered (recovery rate: 63.0%) at 10 days PI. The main location of the larvae was the body muscles of the fish. No morphological alterations or death of the larvae were observed in this study. From these results, it seems that the C. urotaenia has characteristics suitable to be the host to the larvae and they may serve as the second intermediate and paratenic host in the natural life cycle of this nematode.

Animals↗
PubMed1989

Radiolabeling of infective third-stage larvae of Strongyloides stercoralis by feeding [75 Se]selenomethionine-labeled Escherichia coli to first- and second-stage larvae.

A technique is described for radiolabeling Strongyloides stercoralis larvae with [75Se]selenomethionine. Cultures of an auxotrophic methionine-dependent stain of Escherichia coli were grown in a medium containing Dulbecco's modified Eagle's medium supplemented with 5% nutrient broth, amino acids, and [75Se]selenomethionine. When the 75Se-labeled bacterial populations were in the stationary phase of growth, cultures were harvested and the bacteria dispersed on agar plates to serve as food for S. stercoralis larvae. Use of nondividing bacteria is important for successful labeling because the isotope is not diluted by cell division and death of larvae attributable to overgrowth by bacteria is prevented. First-stage S. stercoralis larvae were recovered from feces of infected dogs and reared in humid air at 30 C on agar plates seeded with bacteria. After 7 days, infective third-stage larvae were harvested. The mean specific activity of 6 different batches of larvae ranged from 75 to 330 counts per min/larva with 91.8 +/- 9.5% of the population labeled sufficiently to produce an autoradiographic focus during a practicable, 6-wk period of exposure. Labeled infective larvae penetrated the skin of 10-day-old puppies and migrated to the small intestine, where the developed to adulthood.

Animals↗
PubMed2004

The relationship between IgA activity against 4th-stage larvae and density-dependent effects on the number of 4th-stage larvae of Teladorsagia circumcincta in naturally infected sheep.

The number of Teladorsagia circumcincta 4th-stage larvae in naturally infected lambs from a single farm varied among lambs and among different years. Within each year the distribution of 4th-stage larvae among lambs was similar to that expected from a negative binomial distribution. The ratio of 4th-stage larvae to adult T. circumcincta was low in two years with a low mean intensity of infection but high in two years with a higher mean intensity of infection. The negative binomial distribution is defined by the mean and by k, a parameter that measures dispersion; k was low when mean infection intensity was low but higher when mean infection intensity was high. As k is an inverse index of overdispersion this indicated that the distribution of 4th-stage larvae was more overdispersed at low levels of infection. In a combined analysis, the number of adult T. circumcincta and the plasma IgA activity against 4th-stage larvae were both associated with increased numbers of 4th-stage larvae. There was a statistical interaction between the number of adults and IgA activity that moderated their combined effect.

Abomasum↗
PubMed1984

Radiolabeling of Brugia malayi infective larvae in mosquitoes with 75Se-methionine and detection of these larvae in tissues of the Mongolian jird by autoradiography.

Through preliminary experiments, an effective method for radiolabeling Brugia malayi-infected mosquitoes in order to produce labeled infective Brugia larvae was developed. Starting on the 6th day after the infective blood meal, mosquitoes were fed a 7% sucrose solution containing 100 microCi/ml 75Se-L-methionine for 5 days. Infective larvae, retrieved 2 days after this labeling period, averaged 381 +/- 136 counts/min. Jirds were infected with these infective, labeled larvae either by allowing infected mosquitoes to feed on uninfected jirds for 30 min or by inoculating jirds subcutaneously in the groin with washed larvae recovered from mosquitoes. Jirds were killed at various times after infection and were sliced into approximately 0.5 mm thick sagittal sections, which were dried and placed on X-ray film. Autoradiograms were developed after 30-60 days at 5 degrees C. In a sample of 26 inoculated jirds, approximately 30% of the infecting larvae could subsequently be accounted for as Ag degrees foci on autoradiograms. The Ag degrees foci representing larvae were apparent up to 2.5 weeks after infection. In jirds infected by mosquito feeding, the Ag degrees associated with the feeding site persisted for more than 6 weeks after infection.

Aedes↗
PubMed1984

Loss of surface coat by Strongyloides ratti infective larvae during skin penetration: evidence using larvae radiolabelled with 67gallium.

The optimal conditions for labelling infective larvae of Strongyloides ratti with 67gallium citrate were determined. Radiolabelled larvae were injected s.c. into normal and previously infected rats. The distribution of radioactivity in these animals was compared with that in rats infected subcutaneously with a similar dose of free 67Ga by using a gamma camera linked to a computer system. Whereas free 67Ga was distributed throughout the body and excreted via the hepatobiliary system, the bulk of radioactivity in rats injected with radiolabelled larvae remained at the injection sites. Direct microscopical examination of these sites, however, revealed only minimal numbers of worms. When rats were infected percutaneously with radiolabelled larvae, it was found that most radioactivity remained at the surface, despite penetration of worms. When infective larvae were exposed to CO2 in vitro and examined carefully by light microscopy, loss of an outer coat was observed. It was concluded that infective larvae lose an outer coat on skin penetration.

Animals↗
PubMed1977

Skin penetration of infective hookworm larvae. II. The path of migration of infective larvae of Ancylostoma braziliense in the metacarpal foot pads of dogs.

The hairless metacarpal foot pads of six hookworm-free puppies were exposed to infective larvae of Ancylostoma braziliense. Serial sections of the biopts stained with Harris' haematoxylin and eosin showed that the infective larvae are able to penetrate the toughest region of canine skin. Pores of eccrine sweat glands did not seem to constitute sites of entry and no larvae were detected in these glands. Larvae were only observed in the epidermis. The histopathology of the infected skin of the foot pads of the puppies was similar to that in human skin with "creeping eruption" as described by Fülleborn (1927). The biopts appeared to consist of hairy skin as well. In the unexposed adjacent hairy skin of the foot pads, larvae were also observed. They were found in the epidermis, hair follicle systems and dermis, suggesting that the migration from the epidermis into deeper tissue depends on the presence of the hair follicle systems.

Ancylostoma↗
PubMed1992

Hyaluronidase from infective Ancylostoma hookworm larvae and its possible function as a virulence factor in tissue invasion and in cutaneous larva migrans.

During skin penetration, infective hookworm larvae encounter hyaluronic acid as they migrate between epidermal keratinocytes and through the ground substance of the dermis. A hyaluronidase would facilitate passage through the epidermis and dermis during larval invasion. Zoonotic hookworm larvae of the genus Ancylostoma were shown to contain a hyaluronidase activity that migrated on modified sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) hyaluronic acid gels with an apparent Mr of 49,000. A second form with an Mr of 87,000 was also identified. The major etiologic agent of cutaneous larva migrans, A. braziliense, was shown to have the greatest enzyme activity, hydrolyzing up to 3.3 micrograms of hyaluronic acid per h per micrograms of total parasite protein at pH 6.0, whereas A. caninum and A. tubaeforme each had much less enzyme activity. The differences in enzyme activities between species correlated with differences in the intensities of the lytic zones at 49 and 87 kDa on SDS-PAGE hyaluronic acid gels. Hookworm hyaluronidase activity exhibited a broad pH optimum between 6.0 and 8.0 and did not hydrolyze chondroitin sulfate, two features that suggest that the hookworm enzyme is more like the invertebrate leech hyaluronidase than mammalian testicular or lysosomal hyaluronidase. Larvae of A. braziliense were shown to release hyaluronidase activity and degrade radiolabeled hyaluronic acid in vitro. Gold sodium thiomalate was identified as an enzyme inhibitor. The hyaluronidase is the second major virulence factor that we have identified from infective hookworm larvae.

Ancylostoma↗
PubMed1998

Histopathological and histochemical changes in honeybee larvae (Apis mellifera L.) after infection with Bacillus larvae, the causative agent of American foulbrood disease.

Morphological, histochemical and cytochemical changes were examined in honeybee larvae after infection with the bacterium Bacillus larvae. The results indicate cell necrosis in the midgut epithelium accompanied by increasing cell vacuolization and nuclear pyknosis following per os inoculation with B. larvae. Many autolysosomes were positive for acid phosphatase. Non-vacuolar acid phosphatase activity was also found in lysed cell compartments. No such activity was found in regenerative epithelial cells. Degradation of haemocytes, salivary glands and other tissues was also observed. Histochemical analyses after per cutaneous inoculation with B. larvae of three- and five-day-old honeybee larvae show intense non-vacuolar acid phosphatase activity followed by disintegration of infected salivary glands, epithelial cell cytoplasm and haemocytes.

Acid Phosphatase↗
PubMed1996

Trichinella spiralis: X-ray analysis of the nurse cell-muscle larva complex after exponential growth of the larva.

The energy-dispersive X-ray analysis (EDXA) method was employed to determine how the exponential growth of the Trichinella spiralis larva affect the concentration of some metabolically active elements such as phosphorus, sulfur, sodium, chlorine, potassium, and calcium in host myocytes as well as inside the nurse cell-muscle larva complex. Two observations are noteworthy. First, the capsule of the complex reveals the highest Na+ and Cl-concentrations. We would suggest that these high Na+ and Cl-concentrations could be a part of the capsule-localized transport mechanisms covering the metabolic demands of the larva. Second, a substantial increase in the P concentration in the cells inside the complex, i.e., the nurse cell, somatic muscle of the larva, and larval stichosome was found. We postulate that energy metabolism in the nurse cell is entirely dependent on the metabolic requirements of the larva and that they remain together as one functional unit.

Animals↗
PubMed1998

Trichinella pseudospiralis: X-ray analysis of the infected muscle cells and the muscle larva compartments after exponential growth of the larva in situ.

The distribution of nutrients such as Na, Cl, K, P, S, and Ca was investigated by energy-dispersive X-ray microanalysis (EDXA) on bulk-frozen mouse muscles infected with Trichinella pseudospiralis. In an attempt to gain information as to whether muscle larvae would modify the element status within muscles of their host. Significant increases in phosphorus concentrations within nurse cells and internal cells of the larva, e.g., the somatic muscle cells and the stichocytes, were shown. This could reflect changes in the energy metabolism and/or in the turnover of nucleic acids of the nurse cell. High phosphorus concentrations within the internal larva cells corresponded to high levels of expression of thymidylate synthase shown elsewhere in both T. pseudospiralis and T. spiralis muscle larvae, most likely reflecting more intensive DNA replication. Furthermore, the Na+-concentration gradient between the nurse cell and neighboring host muscle cells indicated the plasma membrane as a diffusion barrier for Na+. Moreover, the cuticle seemed to maintain the Cl--concentration gradient between the nurse cell and the internal cells of the larva. Nevertheless, the mechanisms involved in the transport of both ions, the collagen cuticle appeared, strong permeability that serves the transcuticular transport maintaining the Cl--concentration gradient.

Animals↗
PubMed1986

A freeze-fracture study of the body wall of adult, in utero larvae and infective-stage larvae of Trichinella (Nematoda).

The surface layers of the cuticle, the hypodermal membranes and the muscle membranes of the adult, the in utero larvae and the infective-stage larvae of the nematode Trichinella spiralis have been studied by means of the freeze-fracturing technique. The surface of the cuticle of both adults and larvae fractures in ways different from membranes of internal cells. The surface coat on top of the epicuticle is probably the layer that changes antigenically. Reticulate ridges, with associated particles, on the E face of the outer hypodermal membrane of the adult are probably sites of attachment of the hypodermis to the cuticle. Longitudinally arranged ridges, with associated particles, of the outer hypodermal membrane are probably points of attachment to the cuticle in the in utero and infective larvae. Rectilinear arrays of particles are present on the P face of the inner hypodermal membrane and the P face of the muscle membrane adjacent to the hypodermis of adults and larvae and probably play a role in adhesion of the muscle membrane to the hypodermis. Particle-free areas of membrane lie external to the Z bundles of the muscle cell and are similar to the sites of attachment of Z lines in insect muscles.

Animals↗