Developmentally regulated lectins in Eimeria species and their role in avian coccidiosis

Avian coccidiosis caused by Eimeria species is characterized by rather specific site infections of the intestine. We used hemagglutination and hemagglutination inhibition assays on various developmental stages of Eimeria tenella and on sporozoites of Eimeria acervulina and Eimeria maxima to assay for parasite lectins. Various monosaccharides, polysaccharides, and glycoproteins were used to demonstrate differences in sugar specificity of the lectins between these species. Surface lectins were found on the primary infective stage, i.e., sporozoites, but not on merozoites or unsporulated oocysts. Also, there were differences in the specificities of the various sugar lectins among the different parasite species. Furthermore, there was a dose-dependent reduction of infection of tissue culture cells by sporozoites of E. tenella that were continuously exposed to fetuin, 1 of the specific inhibitors of the lectin. The results of our study are unique in that in 3 species of avian Eimeria all have a lectin on their sporozoites, but the lectins for each species have different sugar specificities. We hypothesize that these lectins found on the surface of the sporozoites may play a role in determining the site of infection within the intestine of the host.

Identification of a developmentally regulated sialidase in Eimeria tenella that is immunologically related to the Trypanosoma cruzi enzyme

Sporozoites and merozoites of three species of Eimeria, E. tenella, E. maxima, and E. necatrix, that cause diarrhea in chickens worldwide, were examined for their expression of sialidase (SA) activity. The enzyme was found in three species, and the activity of merozoites was 10-20 times higher than that of sporozoites. The enzyme was resistant to degradation by proteases that are normally present in the intestine, a site inhabited by the Eimeria parasites, and it was relatively resistant to heat, with optimum activity being at 40 degrees C, which is within the range of temperature in the chicken intestine (40-43 degrees C). E. tenella SA was immunoprecipitated by monoclonal and polyclonal antibodies raised against the Trypanosoma cruzi SA (TCSA), and enzyme activity was neutralized by these antibodies. E. tenella SA was identified by immunoblots as a doublet of molecular weight 190,000 and 180,000 using, as a probe, anti-TCSA antibodies and antibodies against a synthetic peptide (TR) derived from the long tandem repeat domain of TCSA. Binding of the monoclonal and polyclonal antibodies to E. tenella was completely blocked by TR, but not by an irrelevant peptide (BR). Therefore, E. tenella expresses a developmentally regulated SA that is structurally related to the T. cruzi counterpart. Because of the high SA activity in merozoites, and by analogy with other SA-producing microbes that inhabit mucin-rich epithelia, we suggest that the Eimeria SA plays a role in desialylating intestinal mucins to reduce viscosity of the local environment and thereby facilitate parasite migration. The enzyme could also play a role in host cell-parasite interaction.

Comparative development of Eimeria tenella in primary chick kidney cell cultures derived from coccidia-resistant and -susceptible chickens

A sixfold difference in resistance to coccidia (Eimeria tenella) infection between a resistant and a susceptible line of Auburn White Leghorn chickens, derived by selective breeding, has been reported. The purpose of the following study was to determine whether the resistance or susceptibility phenomenon in the Auburn lines could be manifested in a homogeneous group of isolated host kidney cells that support E. tenella development in vitro but not normally in vivo. Propagation of the parasite in host cells in vitro eliminates humoral and cellular elements of immunity, and allows the study of host genetic influences at the cellular level. Differences in parasite development were examined between the two lines of cells in vitro after 48 and 96 h of incubation; time periods that reflect initial infection of the host cells by the parasite and the subsequent asexual development. Quantification of differences by liquid scintillation counting was based on parasite-specific incorporation of pyrimidines, specifically [3H]-uracil. The results supported previous findings that overall E. tenella development was significantly greater in the host cells from the susceptible line than in the cells from the resistant cultures at both time periods.

Characterization of resistance and immunity to Eimeria tenella among major histocompatibility complex B-F/B-G recombinant hosts

The relative influence of the B-F vs. B-G chromosomal regions on innate resistance and immunity to Eimeria tenella was studied among six B-F/B-G recombinants, designated BR1, BR3, BR4, BR5, BR6, and BR8. In one experiment, resistance was studied among 340 F1 chicks each carrying the B17 allele derived from Line UCD.003 and therefore also heterozygous for one of the B recombinant haplotypes. In a second experiment, acquired immunity was studied among 161 F2 chicks each carrying one B17 allele and segregating for one of the recombinant alleles. In Experiment 1, F1 chicks of similar haplotypes, BR3 and BR4 (BF2-G23), gained significantly more weight than those with BR1 (BF24-G23) and BR5 (BF21-G19) following exposure to a single high dose of 25,000 oocysts, although no differences in lesion scores were detected among the six recombinants. Following exposure to a single low dose of 2,500 oocysts, F1 chicks BR3 and BR4 also gained significantly more weight and had significantly lower lesion scores than BR1 or BR5 F1 chicks. To study acquired immunity in the F2 homozygous chicks, five consecutive daily exposures of 500 oocysts were followed 21 days later by challenge with 10,000 oocysts. The BR5 (BF21-G19) and BR6 (BF21-G23) homozygous chicks, both carrying the B-F21 allele, showed significant protection in terms of reduced lesion scores. These results demonstrate that E. tenella parasitism manifests itself to varying degrees in chicken hosts possessing different recombinant major histocompatibility complex haplotypes.

Glycoconjugates of the intestinal epithelium of the domestic fowl (Gallus domesticus): a lectin histochemistry study

A lectin histochemical study was performed on formalin-fixed paraffin-embedded tissues of duodenum, jejunum, ileum, caecum and colon from six fasted and six non-fasted 8-week-old chickens (Gallus domesticus). The purpose of this study was to identify in situ the pattern of carbohydrate residues present on the luminal surface of the intestinal epithelium. Ten biotinylated lectins with different sugar specificities were used as probes, and avidin-biotin-peroxidase complex (ABC) was used as a 'visualant'. The most significant finding was the binding pattern of Lens culinaris agglutinin to various segments of the intestines. The luminal surface of the small intestinal epithelium did not stain with this lectin. In the colon the luminal surface was lightly stained, while the caecal luminal surface was intensely stained. Throughout the intestine the luminal surface stained with Canavalia ensiformis agglutinin, Ricinus communis agglutinin-I and wheatgerm agglutinin, but it did not stain with Dolichos biflorus agglutinin. These findings indicated that, throughout the intestine, the luminal surface contains glycoconjugates with either N- or O-linked glycoprotein, or both, with terminal non-reducing beta-galactosyl and sialyl residues. Furthermore, the caecal surface is rich in N-linked glycoproteins with an alpha-(1----6)-linked fucosyl residue near the glycosidic linkage. The potential significance of these observations and the role of glycoconjugates in host-parasite interaction (i.e. Eimeria sp. versus Gallus domesticus) are discussed.

Bile and serum immunoglobulin levels during primary and secondary infections with Eimeria tenella in chickens

Using a radial immunodiffusion assay, total bile and serum IgG, IgM and IgA were measured following primary and secondary exposures to Eimeria tenella. Neither IgG nor IgM could be detected consistently in bile. Biliary IgA peaked at Days 6 and 10 following a primary infection of either 5000 or 10,000 oocysts and remained elevated following a subsequent 10,000-oocyst challenge at Day 10. Serum IgG and IgM levels were not influenced by parasitism and measurable concentrations of serum IgA were not detected.

Major histocompatibility (B) complex effects on acquired immunity to cecal coccidiosis

The influence of the major histocompatibility (B) complex on acquired immunity to the avian coccidium Eimeria tenella was studied in 217 F4 segregants (B2B2, B2B5, B5B5) of a cross between inbred lines 6(1) (B2B2) and 15(1) (B5B5) and segregating haplotype combinations of UNH105 (B23B23, B23B24, B24B24), a noninbred line of New Hampshire chickens. Chickens were immunized at 6 weeks of age with 500 oocysts daily for 5 days, then challenged 14 days later with 10 000 oocysts. Responses to infection were evaluated by cecal lesion scores, body weight gain, delayed wattle reaction (DWR), and spleen weight. The F4 segregants of genotypes B2B5 and B5B5 exhibited greater immunity to challenge than B2B2 chickens. B5B5 chickens showed a significantly greater DWR following immunization and larger spleens 6 days after the challenge than either of the other genotypes. However, both B2B5 and B5B5 chickens demonstrated significantly lower lesion scores than B2B2 chickens. There were no significant differences in weight gain among these genotypes. Among 139 line UNH105 segregants, B23B23 hosts had significantly lower lesion scores than B24B24 chickens. No other differences in immune response among line UNH105 genotypes were detected.

Pathogenic Vibrios in Confinement-Reared and Feral Fishes of the Maine–New Hampshire Coast

Vibrio anguillarum was isolated from moribund or fresh dead confinement-reared or feral fishes from the Maine–New Hampshire coast. All Vibrio isolates were tested for pathogenicity by inoculation into 12–15 cm-coho salmon (Oncorhynchus kisutch) smolts reared in fresh water. In 1975, of 35 isolates from confinement-reared fishes, 29 were Vibrio and 22 of these killed test fish; 1 of 4 isolates from feral fishes was a pathogenic Vibrio. In 1976, of 69 isolates from cultured fishes, 52 were Vibrio and 12 were pathogenic; 39 of 59 isolates from feral fishes were Vibrio, yet only 1 was pathogenic. One group of Vibrio isolates, all from winter flounder (Pseudopleuronectes americanus), killed all salmon smolts the same day of injection; one strain (569) consistently killed smolts within 3–4 h after inoculation. With microtiter methods, agglutinin titers of rabbit antisera were determined against all pathogenic V. anguillarum isolates. Three distinct antigenic groups of V. anguillarum, confirmed by agar-gel diffusion and challenge, were found on the Maine–New Hampshire coast. Although two of these groups appear to be antigenically similar to West Coast strains 775 and 1669, a third group shows little relationship to other East Coast–West Coast serotypes. Key words: Vibrio anguillarum, coho salmon, pathogenic Vibrio, confinement-reared (cultured) fishes, serotypes, agar-gel diffusion

Prevalence of meningeal worm (Parelaphostrongylus tenuis) in white-tailed deer from New Hampshire

Parelaphostrongylus tenuis was found in 79 (62.2%) of 127 white-tailed deer heads (Odocoileus virginianus) collected in New Hampshire. Prevalence of infection was higher in fawns and male deer, but older female deer (5.0 + years) had a higher intensity of infection (3.1) than any other age or sex class. Male deer in forest cover type 2 (northern hardwoods-hemlock-white pine) had a significantly greater prevalence of infection than the females in the same habitat (P less than .05). Adult females had a higher prevalence of infection (67.0%) than female fawns (20%) in forest cover type 1 (spruce-fir-northern hardwoods). In the craniums examined, P. tenuis was found most frequently in the tentorium cerebelli (23.6%) while the falx cerebri, the most prevalent site of infection in fawns, was a significantly less frequent site of infection in older deer (P less than .02). Male deer of age class 3.5 years had a significantly higher rate of infection in the dura mater-olfactory lobe than any other age or sex group (P less than .02). The cavernous sinus was the most frequent site of parasitism in male fawns (25.0%) and was the second most common location in all deer (13.4%).

Gametogony of eimeria tenella (coccidia) in cell cultures

Mature male and female gametocytes of Eimeria tenella, a coccidium of the chicken ceca, developed in primary cultures of chick embryonic kidney cells inoculated with sporozoites. Immature gametocytes appeared in the cultures after approximately 144 hours of incubation at 41 degrees C. Mature micro-and macrogametes were present from 160 to 190 hours after inoculation.