Human infections with Trichinella spiralis and respiratory syncytial virus (RSV) are common, as T. spiralis infections are re-emerging in various parts of the world and RSV infections remain a threat for infants. Yet, studies investigating the relationship pertaining to the two are severely lacking. In particular, immune response induction via RSV and T. spiralis remain largely elusive. Here, we investigated the resistance against T. spiralis infection induced upon primary infection with RSV. RSV, notorious for causing severe inflammatory reaction in the lungs, were intranasally infected, followed with a T. spiralis infection in mice. Our results revealed that primary RSV infection in mice significantly raised T. spiralis-specific and total IgE, IgG and its subclass antibody responses upon T. spiralis challenge infection (RSV-Ts). Blood eosinophil levels were decreased in RSV-Ts, accompanied with significant increase in both Th1 and Th2 cytokines. Antibodies generated against RSV in RSV-infected mice were found to react with T. spiralis excretory/secretory antigen, showing several bands determined through immunoblotting. RSV-Ts also had a marked reduction of T. spiralis worm burden in diaphragm. These results indicate that immune responses induced by RSV infection contribute to resistance against subsequent T. spiralis infection.

Fever is a common adverse event following measles vaccination, more frequent among older children and those receiving Measles-Mumps-Rubella-Varicella vaccine vs. Measles-Mumps-Rubella vaccine, two factors associated with a better antibody response. However, the role of fever in the immunogenicity of measles-containing vaccines (MCV) is unclear. We performed a post-hoc pooled analysis of data of 5 216 11 to 22 month-old children receiving MCV from 2004 to 2012 in Europe and USA to evaluate the association between post-immunisation fever and antibody response, measured by geometric mean concentrations (GMCs). We further evaluated fever as an effect modifier or a mediator in the associations between the type of MCV or the age at first vaccination and vaccine immunogenicity. After the first dose, fever was associated with 60% higher GMCs (95% CI 1.51–1.68). For children vaccinated at ⩾12 months, the fever did not modify and minimally mediated (2% to 3%) the association between age and antibody response. Fever mediated 18% of the association between type of MCV and GMCs. In a model including fever, age and type of vaccine, fever was the strongest predictor of GMCs. These results suggest that fever is associated with a stronger measles antibody response independently of age and type of MCV.

The intraspecific diversity of Neospora caninum is a determinant for in vivo parasite virulence and in vitro parasite behaviour. The relationship between isolate virulence and specific antibody responses against key parasite proteins has not been well characterized. The response kinetics and the differences in specific anti-rNcGRA7, -rNcSAG4, -rNcBSR4 and -rNcSRS9 antibody levels were analysed by recombinant protein-based ELISA in groups of mice inoculated with 10 different N. caninum isolates that differ in their virulence. The majority of the virulence parameters analysed correlated with the specific antibody levels against the 4 recombinant proteins. The antibodies developed against the highly immunogenic protein NcGRA7 were significantly higher in mice inoculated with high virulence isolates than in those inoculated with low-to-moderate virulence isolates in both non-pregnant and pregnant mouse models. Moreover, these levels were correlated with the anti-N. caninum IgG1 and IgG2a responses and the in vitro tachyzoite yield at 56 h. The antibodies directed against the bradyzoite-specific proteins were not detected in a non-pregnant mouse model. However, some seropositive mice were found in groups inoculated with high virulence isolates in a pregnant mouse model. NcGRA7 and NcSAG4 are proteins clearly correlated with virulence, and to a lesser extent NcBSR4 and NcSRS9 proteins. Moreover, antibodies to bradyzoite-specific proteins appear to also be related to virulence in mice. Further analyses should be performed in order to verify the usefulness of these proteins as predictive markers for virulence in an experimental bovine model of neosporosis.

Groups of 10 Mongolian gerbils. Meriones unguiculatus, were vaccinated with 1,500 gamma-irradiated Trichostrongylus colubriformis infective larvae (L3) or with non-irradiated larvae. 25 days later five gerbils from each group were necropised and the remaining gerbils challenged with 1,500 non-irradiated T. colubriformis infective larvae. Systemic, local intestinal and coproantibody levels were compared in each group of gerbils 25 days after vaccination and 26 days after challenge. Strong local intestinal and faecal antibody responses were detected. Coproantibodies reflected antibody levels in the intestinal contents and in mucosal extracts. The results gave further support to the view that coproantibody measurements provide a sensitive index of immunity at mucosal surfaces to intestinal parasites.

The serum antibody response in golden hamsters (Mesocricetus auratus) infected with the intestinal trematode Echinostoma caproni was examined with ELISA, SDS-PAGE and Western blot, and IFAT techniques. All methods showed that the hamsters responded slowly but developed a clear positive humoral response to the infection. In most hamsters, an antibody response to infection could not be detected earlier than 11–13 weeks after infection with 6 or 25 metacercariae, and responses were weak when compared to previous results from mice infected with the same parasite. IFAT with positive hamster sera on live juvenile E. caproni showed only fluorescence at the posterior tip, which is a different pattern from that seen using sera from infected mice, indicating a different response to antigens on the juvenile parasites by these two hosts. The results are discussed in relation to the limited selfcure and development of resistance which is observed in golden hamsters infected with E. caproni.

A series of experiments was carried out using adult outbred Polish race rabbits of both sexes infected, during spring or autumn. with 10 000 larvae of Obeliscoides cuniculi, either fresh or stored at 4°C. Extracts of mucosal proteins and bile were collected at postmortem 6 or 12 weeks after infection. Antibody levels were determined in antisera. bile and stomach mucosa by haemagglutination and precipitation tests. Local antibody respones were demonstrated in the stomach and bile, and reactions were obtained with the tissue fluids by haemagglutination and precipitation tests with worm antigens and ES products. Additionally, some specific immunological response was observed in the circulation during the primary infection. These results suggest a clear-cut relationship between increased levels of these antibodies and either larval inhibition or worm expulsion during O. cuniculi infections.

Probiotics such as lactic acid bacteria directly influence the host’s health and have beneficial effects such as decreasing the number of enteric pathogens, regulating intestinal immune responses and preventing diseases. Among domestic animals, probiotics have been expected to be an alternative to antibiotics added in the diet; and fermented liquid diet (FLD) containing probiotics has great potential as a diet for reducing the use of antibiotics. In this study, we evaluated the immunomodulatory effects of FLD, prepared using Lactobacillus plantarum LQ80 (LQ80), on the immune response of weaning pigs. Ten weaning piglets were divided into two groups and were fed the FLD (n = 5) or a non-fermented liquid diet (NFLD) (n = 5) for 28 days. At the end of the experiment, the total immunoglobulin M (IgM) and immunoglobulin G (IgG) levels in the sera of the FLD-fed piglets were significantly higher than those of the NFLD-fed piglets (P < 0.05). In contrast, the total immunoglobulin A (IgA) levels in the feces and saliva were not significantly affected by FLD feeding. However, the mean fecal IgA levels of FLD-fed piglets at day 28 were higher than those at 14 and 21 days (P < 0.05). Blood cells from the FLD-fed piglets showed a low level of interferon-γ secretion and mitogen-induced proliferation compared to that of the NFLD-fed piglets. Furthermore, the levels of interluekin-8 and tumor necrosis factor-α, which are proinflammatory cytokines, in the blood cells of the FLD-fed piglets were lower than those of the NFLD-fed piglets (P < 0.05). In conclusion, the FLD used in this study could alter the immune responses of weaning piglets by stimulation of the systemic or mucosal antibody response, without unnecessary inflammatory reactions. This indicates, that the FLD feed prepared with the use of LQ80 may be a candidate feed, with regard to enhancing immune responses and preventing diseases in weaning piglets.

Sera from goats and cattle that were infected with two Trypanosoma vivax clones (ILDat 1.2 and ILDat 2.1) derived from different stocks were analysed for antibody activity against the variable surface glycoproteins (VSGs) of the infecting clones by enzyme-linked immune assays (ELISA) and immune lysis. To obtain purified VSG, lysed trypanosomes were separated on dodecyl sulphate-polyacrylamide gels. The gels were copper stained and the VSG protein band was excised from the gel. After destaining, the proteins were electroeluted from the gel slices and used as antigens in ELISA. High titres of IgM and IgG1 antibodies and lytic antibodies against the VSG of the infecting clone were detected. The IgG1 response appeared about 4 days later than the IgM response. IgG2 antibodies were only detected in goats and cattle that were infected with ILDat 1.2. Two goats and two calves that were infected with ILDat 1.2 showed recurrent peaks in lytic activity and of IgM and IgG1 antibody activity to the VSG of the infecting variable antigenic type (VAT). Two goats that were infected with ILDat 2.1 showed a similar pattern, but in two other goats there was a recurrent peak only in the IgM class. Recurrent peaks of antibody activity to the VSG of ILDat 1.2 and ILDat 2.1 were not detected in the sera of goats that had been inoculated with irradiated trypanosomes or that had been infected with an unrelated T. vivax clone. The recurrence of antibody peaks against the VSG of infecting VATs suggests that trypanosomes with completely or partially identical surface determinants reappear during T. vivax infection of ruminants.

The effects of exposure to infective larvae on the antibody response to a cocktail of specific recombinant antigens of Onchocerca volvulus and to a worm extract were evaluated by comparing the responses of individuals from a vector controlled area with those from an area of continuing transmission by ELISA. Individuals from the vector controlled areas were found to have reduced responses to both antigen preparations. Amicrofilerdermic (mf–) individuals from the area of vector control exhibited significantly lower total and subclass IgG responses to the worm extract. In contrast, the responses to the cocktail of specific recombinants were significantly reduced in individuals from the area of vector control who were still microfilerdermia positive (mf+). The distribution of IgG subclass specific responses was similar to both antigen preparations, both dominated by the IgG4 and IgG1 subclasses. IgG1 responses to the worm extract remained elevated in the vector controlled individuals but IgG4 was significantly reduced in the mf – individuals. Both subclasses reflected the total IgG response to the cocktail of recombinants and were significantly reduced in individuals from the vector controlled area, when compared to individuals from the hyperendemic area. IgG1 responses to the cocktail of recombinants are significantly lower than IgG4 in all individuals and virtually absent in individuals from the vector-controlled area. Measuring total IgG and IgG4 is more sensitive than IgG1 in detecting infection, 100 or 97% respectively, but they remain elevated in the individuals from the vector controlled areas even after 8–10 years interruption of transmission. These results have important implications for the serological monitoring of control programmes in individuals who have previously been infected.

Serum from uninfected mice of different strains, as well as from germ-free animals, contains antibodies which react specifically with at least two trypanosomal proteins, I/6 and MARP1. These antibody populations are highly specific for the respective proteins, are of similar affinity as hyperimmune antibodies, and consist of IgM as well as IgG isotypes. Hyperimmune antibody raised against the cross-reacting trypanosomal protein I/6 detects a 60 kDa protein in mouse 3T6 cells, which is a component of the fibroblast cytoskeleton.

The present study compares parasite-specific antibody responses in two Caribbean communities with high and low levels of Trichuris trichiura transmission. The age-dependency of antibody levels suggest that IgG1 and IgG2 levels relate to the current intensity of infection (as assessed by density of eggs in stool (e.p.g.) and reflect the age–intensity profile at the population level. IgG4, IgE and IgA levels persist into early adulthood and the subsequent decline is gradual. In the low transmission area, lower infection levels are reflected in lower parasite-specific antibody levels (of all isotypes) in the community as a whole. Despite a significantly greater past experience of infection in the high transmission area, antibody levels are not maintained at significantly higher levels throughout adulthood. The production of IgA appears to require a threshold for triggering, and a vigorous IgA response is maintained into early adulthood only in the high transmission village where peak intensity is greatest and the age-convexity of intensity is most marked. Experimental and theoretical studies focusing on the dynamic nature of host–helminth interactions in hosts exposed to high and low infection levels, and the putative role of acquired immunity, are discussed in relation to the data presented.

Baseline data from an immuno-epidemiological study of hookworm infection in a rural village in Madang Province, Papua New Guinea are reported. Necator americanus was found to be the commonest helminth infection, with a prevalence of near 100% and intensity of 40 worms per host in adults. Enterobius vermicularis, Ascaris lumbricoides and Trichuris trichiura were also present, at prevalences of 53, 10 and 3% respectively; Ancylostoma duodenale was absent. The frequency distribution of N. americanus was highly over-dispersed, and was well described by a negative binomial distribution with aggregation parameter, k, of 0·370. Intensity of infection was significantly related to host age, but did not differ between the sexes. Haemoglobin levels and haematocrit values were indicative of anaemia in the community, but were unrelated to hookworm infection. Levels of antibodies (IgG, IgA and 1gM combined) against adult Necator cuticular collagen and excretory-secretory (ES) products were determined.

Strains of mice poorly (B10) or non-responsive (B10.BR) to a primary infection with Trichuris muris were protected against infection by vaccination with excretory/secretory (E/S) antigen in Complete Freund's Adjuvant (CFA). Protection in these mice was slow to be expressed compared to that in good responder strains. Vaccination boosted the IgG and IgG1 antibody responses to E/S antigen and altered the antigen recognition profiles, three high molecular weight antigens (80–85, 90–95, 105–110 kDa) being recognized by antibodies in sera from vaccinated but not control mice. B10. BR mice which had experienced a patent primary infection could not be protected against challenge infections by vaccination and this was correlated with depressed levels of IgG1, but not total IgG, to E'S antigen early post-challenge compared with vaccinated infected mice which had not seen an adult primary infection. There was also lack of recognition of the three high molecular weight antigens recognized by antibodies in sera from mice infected after vaccination. It is suggested that the rapid development of high levels of IgG1 antibodies, and the recognition of the three high molecular weight antigens, may reflect events that are important in protective immunity. Immunomodulation of host immunity by T. muris may therefore be achieved, at least in part, by the suppression of specific IgG1 levels, the production of an irrelevant IgG isotype and prevention of the recognition of critical antigens.

The original host of the swimbladder nematode Anguillicola crassus, the Japanese eel (Anguilla japonica) and the recently colonized European eel (Anguilla anguilla) were immunized with 40 irradiated (500 Gy) 3rd-stage larvae (L3) of this parasite and challenged with an infection of 40 normal L3. The immunization induced a significant reduction of the number of adult worms developing from the challenge infection in A. japonica, but not in A. anguilla. The induced resistance (calculated using the relation of the number of adult worms in immunized eels and in non-immunized control eels) in A. japonica was 87·3%±30·4%. Following a single infection, the percentage of adult worms found in A. japonica was lower as compared to A. anguilla, and the few adult worms were much smaller, revealing a lower susceptibility of A. japonica to A. crassus in comparison to A. anguilla. Both eel species developed an antibody response against A. crassus, but the level of antibody responses was not positively correlated with the protection against infection, suggesting that the antibody response is not a key element in resistance of eels against A. crassus. This study suggests that the original host of A. crassus is able to mount efficient protective immune responses against its parasite, whereas the newly acquired host seems to lack this ability.

The individual and combined effects of cadmium (Cd) and 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) on the antibody response of fish against metazoan parasites were tested. Eels experimentally infected with the swim bladder nematode Anguillicola crassus were exposed to sublethal concentrations of Cd and PCB 126. Cd was added to the water resulting in an effective concentration of 21·7±12·8 μg/l (mean±S.D.). PCB 126 was applied orally at a dose of approximately 100 ng PCB 126 per g body weight. At the end of the experiment, 76 days post-infection (p.i.), eels were found to be infected with 2–3 worms. Immunoblot analyses revealed that the body wall of adult worms was the most suitable crude antigen, and was subsequently used for an ELISA to evaluate the immune response of A. anguilla under various conditions. A significant increase of Anguillicola-specific antibodies in the peripheral blood was first detected 61 days p.i., indicating that it was not the invasive larvae but the adult worms which elicit the antibody response. The presence of Cd in the concentrations applied did not appear to modulate the production of antibodies. In contrast, the exposure to PCB 126 resulted in a complete suppression of the antibody response. A similar effect was also found for the combined exposure of the infected eels to Cd and PCB 126. A suppressed immune response, as demonstrated here, may be the reason why hosts exposed to environmental pollution became often much more easily infected than unexposed conspecifics.

The usefulness of supplementary dietary L-CARNITINE AS AN IMMUNOMODULATOR TO INCREASE ANTIGEN-SPECIFIC ANTIBODY LEVELS WAS ANALYSED IN 2–6-WEEK-OLD BROILERS. THE CHICKENS RECEIVED COMMERCIAL FEEDS EITHER UNSUPPLEMENTED (STARTER FEED 17·8 MG CARNITINE/KG, FINISHER DIET 22·9 MG CARNITINE/KG) OR SUPPLEMENTED WITH l-carnitine (100 mg carnitine/kg added to feed). At 14 d of age, both groups were distributed in equal numbers and sex ratios over two environmentally controlled chambers where temperature (28°) was either reduced immediately to 20°, or gradually to 22° at 36 d of age. Antigen-specific immunoglobulin (Ig)M, IgG, IgA and total Ig responses were measured following two immunizations with bovine serum albumin (BSA). The typical BSA-specific IgM responses followed by IgG responses to the primary immunization were boosted by the secondary immunization. The kinetics of these responses were not altered by l-carnitine treatment. However, BSA-specific total Ig and IgG, but not IgM, responses were significantly increased by dietary l-carnitine supplementation, after both the primary and the secondary immunization. No significant influence of the sex of the chicks or the imposed environmental temperature on Ig responses was found. Temperature treatment and sex, but not l-carnitine supplementation, did significantly influence body-weight gain: cockerels were heavier than females and this became most evident in the second half of the rearing period. Further, lowering the temperature increased body weight. In conclusion, dietary l-carnitine supplementation appeared to be beneficial in enhancing specific humoral responses on vaccination.

The humoral antibody response and the number of pronephric antibody-secreting cells were examined in naturally Bothriocephalus acheilognathi-infected carp. Cyprinus carpio, and in those injected intraperitoneally with an extract of the cestode. In the extract-injected fish, specific antibody was detected 3 weeks after a second injection given 2 weeks after the primary injection, and antibody levels persisted for more than 200 days. A third injection also enhanced the antibody level in the extract-injected carp. The numbers of antibody-secreting cells were significantly higher in carp injected 3 times with the extract than in the control. In naturally-infected fish, the serum antibody levels and the number of pronephric antibody-secreting cells were higher in infected fish than in uninfected individuals although this difference was not statistically significant. The relevance of these results to immune protection against infection is discussed.

The effects of dietary protein and zinc restrictions on Heligmosomoides polygyrus were compared following primary and challenge infection in female BALB/c mice fed either control (24%), marginal (7%) or low (3%) protein combined with either high or low zinc (60 or 3 mg Zn/kg diet). Dietary protein restriction (3%) resulted in significantly lower body weight gain. As well, blood urea nitrogen (BUN) significantly decreased with decreasing dietary protein level. However, neither plasma albumin concentration nor relative thymus or spleen weights were reduced. Marginal zinc deficiency was confirmed by significantly lower tibia and liver zinc concentration, but food intake, body weight gain, relative thymus and spleen weights, and alkaline phosphatase activity were not altered. On day 29 post-primary infection, worm burdens were significantly higher in mice fed either marginal or low protein and in mice fed a low zinc diet, while parasite egg output was significantly higher in mice fed both low protein and low zinc diets. Immune status was compromised in mice fed low protein (significantly lower serum IgG1 and lower eosinophilia), and in mice fed low zinc diet (significantly lower eosinophilia). Early in the infection, IgE titres were elevated in mice fed low protein or low zinc, but IgE titres declined to levels lower than the control diet groups after 14–21 days. On day 29 post-challenge infection, worm burdens and parasite egg output were significantly higher in mice fed low protein, whereas the other groups had expelled almost all parasites. Dietary restriction had no effect on serum IgE. Significantly reduced serum IgG1 titres and eosinophilia in mice fed 3% protein supported the view that low dietary protein but not low zinc increased host susceptibility to H. polygyrus by compromising host immune function following reinfection in immunized mice.

The kinetics of serum antibody response against infection with Echinococcus multilocularis eggs was evaluated in AKR mice. The animals were infected by oral inoculation with 300 parasite eggs, and necropsied at 1, 2, 4, 6, 9, 12 and 16 weeks post-infection (p.i.), respectively. The parasite formed the laminated layer at 4 weeks p.i., the brood capsule with a massive proliferation of germinal cells at 9 weeks p.i. and protoscoleces at 16 weeks p.i. Serum antibody responses of the mice to antigen preparations from metacestodes of different stages and protoscoleces were evaluated by ELISA, immunoblotting and immunohistochemistry. In ELISA, the antibody responses began to increase at 4 weeks and became more apparent at 9 weeks p.i. and thereafter. Immunoblots using sera collected at 16 weeks p.i. showed some common bands among the 3 different antigen preparations. In addition to this, the germinal cells and brood capsules of mature metacestodes were stained strongly in an immunohistochemical study. From above, it is suggested that some antigen molecules are expressed in the parasite through these stages and stimulated host antibody responses.