Transfer of toxicants from exposed nymphs of the drywood termite Incisitermes snyderi (Isoptera: Kalotermitidae) to unexposed nestmates

Two formulations of spinosad (NAF-85 and NAF-371) were evaluated to determine the effect of concentration, deposit condition (dried, wet, or topical), and exposure time (0.1-10 h) for toxicant transfer among nestmates in the drywood termite Incisitermes snyderi (Light). Spinosad treatments were compared with two formulations of disodium octaborate tetrahydrate (DOT) (10% aqueous dilution, 98% dust) and with 35% calcium arsenate dust. Termites were dyed and individually exposed to different treatments for 0.1, 1.5,1.0, 5.0, 10.0 h, or 0.1 and 1.0 h (DOT and calcium arsenate dust) and then placed with 10 unmarked, untreated nestmates in a petri dish. Spinosad formulations also were evaluated by topical application to dyed termites. Transfer of lethal doses of toxicants between termites was indicated by significant mortality of untreated termites in 25 of 28 treatments by 28 d after introduction of dyed, treated termites. Only three treatments, one spinosad treatment (NAF-371, wet, 1 h) and both DOT 10% solution treatments, resulted in mortality of untreated termites that was not significantly different than that of water-treated controls. Two spinosad treatments and both calcium arsenate dust treatments resulted in >90% (94-98%) mortality of untreated termites by 28 d after introduction. Mortality of untreated termites was significantly different from controls for the two spinosad formulations, depending on condition of deposit and duration of dyed termite exposure to treatments.     

Reproductive mechanisms and dynamics of habitat colonization in Microcerotermes biroi (Isoptera: Termitidae)

Abstract. 1. Previous studies on the arboreal termite community in coconut plantations of northern New Guinea showed that Microcerotermes biroi is the most abundant species, despite the fighting superiority of two competitor species Nasutitermes princeps and N.novarumhebridarum. In this study we tested the hypothesis that the success of M.biroi is due to its efficiency at colonizing new habitats following nuptial flights.
2. We demonstrated experimentally the ability of M.biroi colonies to replace their reproductives when removed, or to produce reproductives in satellite nests when isolated from the remainder of the colony. Replacement reproductives were always neotenics, derived from nymphs or workers.
3. Despite the ability of neotenics to differentiate within their home colonies, 84% of field colonies were headed by dealated imagos. This value constitutes a minimum estimate of the proportion of field colonies founded independently by imagos after the nuptial flight.
4. The monitoring of a young plantation during the first 31/2 years of its colonization by arboreal nesting termites revealed its invasion by M.biroi , which colonized 63% of the trees while neither Nasutitermes species appeared.
5. Our results demonstrate that M.biroi is actually a pioneer species, able to invade a new habitat by means of nuptial flights. They outline the importance of each species' reproductive strategy in shaping the arboreal-nesting termite community.     

Behavioural and ecological aspects of nuptial flights of the termitophilous phorids Termitophilomyia zimbraunsi and Mesopathusa modesta (Diptera: Phoridae) in Zimbabwe

Nuptial flights of Termitophilomyia zimbraunsi were observed over three years (1990-1993) near the open chimney of an Odontotermes transvaalensis mound in Harare, Zimbabwe. Copulating phoretic pairs landed on the chimney; males quickly disengaged and flew away whilst females ran inside the vent and tore off their wing membranes. Agitated termite workers and soldiers swarmed the rim in a partially successful physical attempt to expel the phorids; the termites appeared to anticipate the threat of invasion. After acquiring the scent of the nest, female phorids ran underground to lay their large single eggs, probably in the hosts'fungus gardens. Nuptial flights occurred throughout the year but only in the early mornings, peaking in the hot dry season and being least in the hot wet season. The flights were highly temperature dependent (15.0-17.9 °), usually occurring at relatively low light intensities but across a wide range of humidities. Phoresy and sexual dimorphism in wings, mouthparts, food and division of labour in T. zimbraunsi are discussed, as is its termitophilous habit and the responses of termites to it.
Although the females of Mesopathusa modesta are apterous, nuptial flight behaviour is very similar to that of T. zimbraunsi. Neither phorid is host-specific, both species having been found on both Odontotermes latericius and O. transvaalensis mounds, although M. modesta is more common on O. latericius mounds.     

Characterization of alveolar macrophage eicosanoid production in a non-human primate model of mineral dust exposure

The relative activation of eicosanoid production which results from the exposure of the alveolar macrophage (AM) to mineral dusts is thought to be a key factor in the pathophysiology of occupational lung disease. We compared in vitro basal and silica-stimulated production of prostaglandin E₂ (PGE₂) and thromboxane A₂ (TXA₂) by AM from normal humans and non-human primates (Macaca nemistrina). In addition, we instilled mineral dusts directly into one lung of the non-human primate and evaluated AM eicosanoid production at two week intervals following dust instillation. Unstimulated AM from humans produce more PGE₂ and TXA₂ than do AM from M. nemistrina. However, in vitro exposure of AM from both species to silica dust produced a qualitatively similar increase in TXA₂ production accompanied by no change in PGE₂ production. Sequential analysis of AM eicosanoid production following a single bolus exposure to bituminous or anthracite coal dusts, titanium dioxide (TiO₂) dust or crystalline silica showed marked variability among individual non-human primates in qualitative and quantitative aspects of dust-induced eicosanoid production. However, the rank order of potency of the different dusts (silica > anthracite > bituminous) correlated with epidemiological evidence relating the type of dust mined to the incidence of pneumoconiosis. These studies suggest that the non-human primate may serve as a model for the study of both the role of eicosanoids in the etiology of dust-induced occupational lung disease and the biochemical basis for individual variability in the response of lung cells to mineral dust exposure.     

Rapid screening of possible cytotoxic effects of particulate air pollutants by measurement of changes in cytoplasmic free calcium, cytosolic pH, and plasma membrane potential in alveolar macrophages by flow cytometry

BACKGROUND: Inhalable particulate dusts are involved in the genesis of several lung diseases. Besides the well-known toxic dusts, i.e., asbestos and quartz, heavy metal-containing pollutants are considered as possible harmful substances. In the present study, we compared the effect of silica chemically coated with certain metal oxides and dusts from industrial productions on cell physiological parameters of bovine alveolar macrophages (BAM). METHODS: The cytosolic free calcium concentration, [Ca2+](i), the intracellular pH (pH(i)), and the plasma membrane potential (MP) of BAM were measured by flow cytometry. The dust-induced secretion of reactive oxygen species (ROS) was measured enzymatically. RESULTS: Compared with control incubations with pure silica, the dust-induced secretion of ROS by BAM was not affected when the particles were coated with Cr(2)O(3), NiO, and Fe(3)O(4), whereas VO(2)-coated dust induced a marked increase in ROS release. This effect was not correlated to changes in [Ca2+](i), pH(i), or MP. On the other hand, Cr(2)O(3)-coated silica caused alterations in all of the three latter parameters. The same pattern of changes has been reported previously for quartz dusts (Tárnok et al.: Anal Cell Pathol 15:61-72, 1997). CONCLUSIONS: We conclude that cell physiological measurements by flow cytometry could extend the palette of tools to evaluate possible toxic effects of environmental dust samples.     

Role of Nitric Oxide in the Progression of Pneumoconiosis

Conflicting evidence has been reported as to whether nitric oxide (NO) possesses anti-inflammatory or inflammatory properties. Data are presented indicating that in vitro or in vivo exposure to selected occupational dusts, i.e., crystalline silica, organic dust contaminated with endotoxin, or asbestos, results in upregulation of inducible nitric oxide synthase (iNOS) and the production of NO by alveolar macrophages and pulmonary epithelial cells. Nitric oxide production is associated temporally and anatomically with pulmonary damage, inflammation, and disease progression in response to occupational dusts. Blockage of inducible nitric oxide synthase by administration of NOS inhibitors or in iNOS knockout mice decreases the magnitude of injury and inflammation following in vivo exposure to silica, endotoxin, or asbestos. Therefore, NO may play an important role in the initiation and progression of pneumoconiosis.     

Efficacy of systemic insecticides for protection of loblolly pine against southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae)

We evaluated the efficacy of the systemic insecticides dinotefuran, emamectin benzoate, fipronil, and imidacloprid for preventing attacks and brood production of southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae) on standing, stressed trees and bolt sections of loblolly pine, Pinus taeda L., in eastern Texas. Emamectin benzoate significantly reduced the colonization success of engraver beetles and associated wood borers in both stressed trees and pine bolt sections. Fipronil was nearly as effective as emamectin benzoate in reducing insect colonization of bolts 3 and 5 mo after injection but only moderately effective 1 mo after injection. Fipronil also significantly reduced bark beetle-caused mortality of stressed trees. Imidacloprid and dinotefuran were ineffective in preventing bark beetle and wood borer colonization of bolts or standing, stressed trees. The injected formulation of emamectin benzoate was found to cause long vertical lesions in the sapwood-phloem interface at each injection point.     

Adsorption of lipoproteins onto mineral dust surfaces: a possible factor in the pathogenesis of particle-induced pulmonary fibrosis?

We compare the adsorption behavior of high density lipoproteins (HDL) and low density lipoproteins (LDL) on "fibrogenic" and "nonfibrogenic" mineral dusts. The adsorption tests with bovine lipoprotein concentrate and human serum produced the following results: 1) All seven examined fibrogenic dusts (SiO2 DQ12, SiO2 F600, silica, graphite, TiC, kaolin, talc) adsorbed significantly more high density lipoproteins (HDL), than the five examined nonfibrogenic (inert) dusts (TiO2, SnO2, Al2O3, Fe2O3, Fe3O4). This different behavior was particularly conspicuous in the presence of competing adsorbates (serum proteins). 2) In contrast, the adsorption of LDL did not correlate with the fibrogenicity of the mineral dusts. 3) The known silicosis-protective substance polyvinylpyridine-N-oxide inhibits the HDL adsorption of alpha-quartz. These results indicate that the adsorption of HDL could have a causal relationship with the triggering of a fibrotic reaction. The adsorption on the surface of fibrogenic dust particles provides an exceptional opportunity for the intake of HDL by macrophages. During the phagocytosis of the inhaled dust particles, the HDL adsorbed on the surface of the particles could be taken up by macrophages regardless of the receptor. There the HDL particles and/or compounds associated with them, such as lecithin-cholesterol-acyltransferase, could stimulate the macrophages to release fibrogenic mediators by some yet unknown mechanism.     

Host discrimination in modular mutualisms: a theoretical framework for meta-populations of mutualists and exploiters

Plants in multiple symbioses are exploited by symbionts that consume their resources without providing services. Discriminating hosts are thought to stabilize mutualism by preferentially allocating resources into anatomical structures (modules) where services are generated, with examples of modules including the entire inflorescences of figs and the root nodules of legumes. Modules are often colonized by multiple symbiotic partners, such that exploiters that co-occur with mutualists within mixed modules can share rewards generated by their mutualist competitors. We developed a meta-population model to answer how the population dynamics of mutualists and exploiters change when they interact with hosts with different module occupancies (number of colonists per module) and functionally different patterns of allocation into mixed modules. We find that as module occupancy increases, hosts must increase the magnitude of preferentially allocated resources in order to sustain comparable populations of mutualists. Further, we find that mixed colonization can result in the coexistence of mutualist and exploiter partners, but only when preferential allocation follows a saturating function of the number of mutualists in a module. Finally, using published data from the fig–wasp mutualism as an illustrative example, we derive model predictions that approximate the proportion of exploiter, non-pollinating wasps observed in the field.     

Co-operativity between modules within a C3b-binding site of complement receptor type 1.

Complement receptor type 1 (CR1) has 30 modules in its extracellular portion. An understanding of structure-function relationships within CR1 is being assembled gradually from studies of overlapping protein fragments. A CR1 fragment corresponding to modules 16 and 17 was expressed recombinantly as a non-glycosylated protein and its stability and unfolding characteristics studied using biophysical techniques. The results were compared with data collected previously on a CR1 fragment encompassing modules 15, 16 and 17 which together constitute a C3b-binding site (Kirkitadze, M.D., Krych, M., Uhrin, D. , Dryden, D.T.F., Smith, B.O., Wang, X., Hauhart, R., Atkinson, J.P. and Barlow, P.N. (1999) Biochemistry 38, 7019-7031). Modules within CR1 were found to co-operate during unfolding. The folding, stability and flexibility of this protein is therefore likely to be a complex function, and not just the sum, of contributions from individual modules.     

Secondary structural features of modules M2 and M3 of barnase in solution by NMR experiment and distance geometry calculation

Proteins consist of structural units such as globular domains, secondary structures, and modules. Modules were originally defined by partitioning a globular domain into compact regions, each of which is a contiguous polypeptide segment having a compact conformation. Since modules show close correlations with the intron positions of genes, they are regarded as primordial polypeptide pieces encoded by exons and shuffled, leading to yield new combination of them in early biological evolution. Do modules maintain their native conformations in solution when they are excised at their boundaries? In order to find answers to this question, we have synthesized modules of barnase, one of the bacterial RNases, and studied the solution structures of modules M2 (amino acid residues 24–52) and M3 (52–73) by 2D NMR studies. Some local secondary structures, α-helix, and β-turns in M2 and β-turns in M3, were observed in the modules at the similar positions to those in the intact barnase but the overall state seems to be in a mixture of random and native conformations. The present result shows that the excised modules have propensity to form similar secondary structures to those of the intact barnase. © 1993 Wiley-Liss, Inc.     

Reaction of cysteine and glutathione (GSH) at the freshly fractured quartz surface: a possible role in silica-related diseases?

The reactivity of quartz dusts towards glutathione (GSH) and cysteine (Cys) has been investigated. Cys and GSH react, without being adsorbed (UV-Vis spectroscopy), with commercial quartz dusts in an exposed surface-dependent way, but not with amorphous silica. GSH and Cys have been contacted with freshly ground quartz (agate jar QZg-a and steel jar QZg-s) and quartz heated in air at 500 degrees C (QZs-500) and with a dust generated from a purified quartz (99.9999%) to detect the nature of the reacting surface sites. With both GSH and Cys, the highest reactivity was found on the particles ground in a steel jar, while pure quartz was fully inactive. Detection of the radical GS* (spin trapping) suggests a radical mechanism of oxidation to disulphide onto surface-bound iron traces, more abundant on QZg-s and absent on the pure quartz. Oxidation of thiol groups occurs at surface sites different from those involved in the homolytic rupture of a C-H bond. Both reactions are more pronounced on freshly ground samples, but the C-H rupture takes place at silicon-based surface radicals and Fe2+ centers, while oxidation of GSH and Cys requires Fe3+ centers. As all commercial quartz dusts contain surface iron as an impurity, depletion of extracellular or intracellular GSH may contribute to the oxidative damage caused by particle-derived and cell-derived reactive oxygen species.     

Spatial network structure and robustness of detritus-based communities in a patchy environment

The mechanisms that regulate the spatial distribution of species are an essential aid to understanding the effects of the environment on the persistence of populations and communities. The effects of spatial structure on the persistence and robustness of ecological communities can, in turn, prove useful in uncovering their functioning, e.g., in the decomposition of leaf detritus. We applied the framework of complex networks to evaluate the effects of spatial structure on the colonization process of leaf detritus in a patchy aquatic environment, with a spatial network of six pools at different salinity. We found three well-defined modules formed by groups of taxa sharing the same pools, observing an association between modularity and spatial proximity of pools. Modules maximize the number of links within modules, and minimize the number of links among modules, showing the presence of a strong site-specific association between taxa and pools. The topological characteristics of the network show robustness against random perturbations and a lower tolerance of targeted perturbations. These findings suggest that random events, such as flooding or heavy rains, slightly affect the robustness of the system, while localized perturbations on the most connected nodes could have a negative effect on the connectivity of the whole network. The consequences could lead to a structural and functional homogenization of the system, with potential effects for the entire trophic chain. Here we discuss the topological properties of the network in relation to the spatial distribution of pools, showing how network analysis can yield valuable insight for conservation and management.     

Capture and immobilization of wild brown palm civets in Western Ghats

A mixture of 15 mg/kg body weight ketamine hydrochloride (KE) and 1.5 mg/kg body weight xylazine hydrochloride (XY) was used to successfully immobilize free-ranging brown palm civets (Paradoxurus jerdoni). Between March 1998 and June 1999, 10 immobilizations of 7 individuals were carried out in tropical rainforests of the Kalakad-Mundanthurai Tiger Reserve (India). Five males and two females were captured in Havahart live traps, using banana as bait. The mean dosage for the animals, whose weight (mean +/- SD) was 2.4 kg +/- 0.8 was 36.0 +/- 11.0 mg KE and 3.7 +/- 1.1 mg XY, administered intramuscularly. Mean time for lateral recumbency was 6.1 +/- 3.78 min (n = 10) and the mean time taken for complete recovery was 84.9 +/- 28.8 min (n = 9). Recovery was gradual and no fatalities or injuries occurred during the operation. The drug combination used was effective and has the potential for immobilizing other viverrids.     

Preventive effects of N‐acetyl‐l‐cysteine against imidacloprid intoxication on Bombyx mori larvae

Imidacloprid, a widely used neonicotinoid insecticide, is toxic to silkworm (Bombyx mori). To explore whether N‐acetyl‐l ‐cysteine (NAC) has an effect on preventing silkworm (B. mori) from toxification caused by imidacloprid, we fed the fifth‐instar larvae with mulberry leaves dipped in 200 mg/L NAC solution before exposing in imidacloprid, and investigated the silkworm growth, survival rate, feed efficiency, cocoon quality, and the activities of antioxidant enzymes in midgut. The results showed that addition of NAC could significantly increase body weight, survival rate, and feed efficiency of imidacloprid poisoned silkworm larvae (P < 0.05), as well as cocoon mass, cocoon shell mass, and the ratio of cocoon shell (P < 0.05). Furthermore, it could significantly promote the activities of the antioxidant enzymes including superoxide dismutase, catalase, and glutathione peroxide in the midgut of fifth‐instar larvae under imidacloprid exposure at the late stage of treatment. In addition, it also could downregulate the malondialdehyde content. The results of our findings proved that the added NAC may have some beneficial effects on protection or restoration of antioxidant balance in imidacloprid exposed larvae.     

Mapping wintering waterfowl distributions using weather surveillance radar

The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998-1999 and 1999-2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of -5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998-1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents.     

THE TOXICITY OF DDT IN ABRASIVE AND NON-ABRASIVE DUSTS TO THE RICE WEEVIL, CALANDRA ORYZAE L. (COLEOPT., CURCULIONIDAE)*

The toxicity of DDT in different dust carriers to the rice weevil, Calandra oryzae , was determined under standardized conditions, using deposits large enough to ensure that the insects accumulated an excess of dust.
Some evidence was obtained that DDT is transported to the cuticle as a vapour.
At high humidity, the toxicity of DDT was not markedly affected by any carrier except charcoal which reduced the toxicity, probably by absorption of DDT vapour. Small differences in toxicity of DDT caused by other carriers could not be accounted for by differences in their average particle size, bulk density, amount adhering to insect, surface area, abrasiveness to insects or effect on behaviour of the insect.
At low humidity, abrasive dusts killed the insects by desiccation, thus adding to the toxic effect of DDT. Abrasion of the insect's cuticle did not affect the apparent rate of penetration of DDT at 50% R. H. or at 95% R. H.
Starved insects were more susceptible to DDT poisoning, and in some experiments abrasive carriers increased the toxicity of DDT by preventing the insects from feeding.     

Arrivals of Hitchhiking Insect Pests on International Cargo Aircraft at Miami International Airport

In a study of hitchhiking or contaminating insect pests on international cargo aircraft at Miami International Airport from 1998 to 1999, it was found that contamination rates were greatest, 23%, on cargo flights from Central America and much lower, near 5%, on flights from all other regions. We reanalyzed the study data to test for associations between contaminated flights and factors such as season, cargo type, and time of departure (night or day), and developed probabilistic models for predicting insect pest arrivals by region and pest risk levels. Significant (P < 0.05) associations were detected between contaminated flights and (1) wet season flights from Central America, (2) flights carrying plant products and clothing or fabrics, and (3) flights departing at night from the country of origin. In Monte Carlo simulations, numbers of arriving mated insect pests were greatest for cargo flights from Central America, because of great contamination rates, and South America, because of the large volume of flights from there. Few insects arrived on flights from the Caribbean, and few high-risk insects arrived from anywhere. Although the likelihood of establishment in South Florida via this pathway could not be estimated, based upon arrivals the greatest threats were posed by moderate-risk insect pests on flights from Central and South America. Simulations indicated that switching to daytime departures only reduced pest arrivals by one-third. The simplest mechanism for pathway entry that explains the associations found is that insects entered aircraft randomly but sometimes remained because of the presence of certain cargo types. Hence, contamination rates were greater during the wet season because of greater abundance locally, and on nighttime flights because of greater abundance around lighted loading operations. Empty planes probably had no pests because pests had no access to holds. Thus, the best mitigation strategies for this pathway will likely be those that exclude insects from holds or reduce the attractiveness of night loading operations. Optimizing inspections based on associations is also possible but will be less effective for regions such as South America, with high flight volumes and low contamination rates. Comparisons to other pathways indicates the potential importance of hitchhikers on cargo aircraft at MIA.     

Dark-bellied Brent Geese Branta bernicla bernicla, as recorded by satellite telemetry, do not minimize flight distance during spring migration

Nine Dark-bellied Brent Geese Branta bernicla bernicla were equipped with satellite transmitters during spring staging in the Dutch Wadden Sea in 1998 and 1999. The transmitters (in all cases less than 3% of body mass) were attached to the back by a flexible elastic harness. One juvenile female was tracked to the Yamal peninsula in 1998. Eight adult males were selected from a single catch of 75 to span the range of body mass observed on the date of capture (11 May 1999) and all but the lightest individual completed the first lap of the migratory flight to the White Sea, Russia, according to the time schedule normal for the species. Six birds were successfully tracked to Taymyr for a total distance averaging 5004 km (range 45775164) but judging from later movements none bred (although 1999 was a breeding year). Although the routes chosen during spring migration were closely similar, none of the tagged birds migrated together. On average the geese used 16 flights to reach their summer destinations on Taymyr. The longest uninterrupted flights during the first half of the journey (Wadden Sea to Kanin) covered 1056 km (mean of seven adult males, range 7681331), while the corresponding value for the second half of the migration (KaninTaymyr) was only 555 km (mean of six adult males). Only 7% of total time during spring migration was spent in active flight, as contrasted to c.  80% at long-term stopovers. Overall average travelling speed was 118 km/day (range 97148). Including fattening prior to departure the rate of travel falls to 62 km/day (range 4970), in keeping with theoretical predictions. Routes followed deviated from the great circle route, adding at least 700 km (16%) to the journey from Wadden Sea to Taymyr, and we conclude that the coastal route is chosen to facilitate feeding, drinking and resting en route instead of minimizing total flight distance.     

Antibody responses against flagellin in mice orally immunized with attenuated Salmonella vaccine strains

Salmonella fIagellin has been repeatedly used as a carrier for heterologous peptide epitopes either as a parenterally delivered purified antigen or as a parenterally/orally-administered, flagellated, live, attenuated vaccine. Nonetheless, the ability to induce specific antibody responses against the flagellin moiety, fused or not with heterologous peptide, has not usually been reported in mice orally inoculated with a live, attenuated, flagellated Salmonella strain. In this work we evaluated the immunogenicity of flagellin in mice following oral inoculation with an aroA Salmonella enterica serovar Dublin SL5929 strain, which expressed plasmid-encoded recombinant hybrid flagellin fused to the CTP3 epitope (amino acids 50–64) of cholera toxin B-subunit. In contrast to parenterally immunized mice, no significant CTP3- or flagellin-specific antibody responses either in sera (IgG) or feces (IgA) were detected following repeated oral delivery of the recombinant Salmonella strain to C57BL/6 mice. Similarly, flagellin-specific antibody responses were also not detected in mice immunized with strain SL5930, which expressed a nonhybrid flagellin. The lack of flagellin-specific antibody responses was not associated with deficient Peyer patch colonization or spleen invasion. Moreover, stabilization of the flagellin-coding gene by integration into the host chromosome did not significantly improve flagellin-specific antibody responses following administration by the oral route. Taken together, these results suggest that flagellin does not represent an efficient peptide carrier for activation of antibody responses in mice orally immunized with live, attenuated Salmonella strains. Received: 29 December 1998 / Accepted: 3 May 1999