iNOs expression is stimulated by the major surface protein (rWSP) from Wolbachia bacterial endosymbiont of Dirofilaria immitis following subcutaneous injection in mice.

The bacterial endosymbiont Wolbachia of several species of filarial nematodes plays an important role in the inflammatory pathology of filariasis. Nitric oxide (NO) production has also been implicated in the immune response during filarial infections. Here we present data indicating that a recombinant Wolbachia surface protein (rWSP) induces iNOs mRNA expression and NO production, as well as IFN-gamma and a Th1-type antibody response, in inoculated BALB/c mice. This effect is not observed when mice are inoculated with a recombinant heat shock protein from Wolbachia (GroEL).

What is happening outside North America regarding human dirofilariasis?

The etiologic agents of human dirofilariasis in the Old World are Dirofilaria immitis, which cause pulmonary and subcutaneous nodules, and Dirofilaria repens, which cause ocular lesions. Although reports of new cases of dirofilariasis are sporadic in other parts of the world, a considerable amount of information is generated in Europe regarding human dirofilariasis. Most cases have been detected in the Mediterranean countries, Ukraine, and Russia; however, isolated or short series of cases have been reported in the Balkan Republics and central and northern European countries. Seroepidemiologic studies have provided evidence that humans living in endemic areas present rates of infection similar to those of the autochthonous canine populations. Antibodies against endosymbiont Wolbachia bacteria have been demonstrated recently in human Dirofilaria infections. During D. immitis infections, preadult worms and third- and fourth-stage larvae are often destroyed by the host reaction, releasing a considerable amount of Wolbachia, and a Th1-type response against Wolbachia and/or filarial antigens is mounted. On the contrary, infections with D. repens, in which worms frequently remain intact, no Th1-type response has been observed. As humans are resistant hosts, the Th1-response could have a role in the resistance against parasites. The causes for the rise in the incidence of human dirofilariasis as well as the possible application of Wolbachia antigens in the serodiagnosis of human infections are discussed.

A coprological and serological survey for the prevalence of Ascaridia spp. in laying hens.

Ascaridia galli is a common nematode found in the intestine of domesticated chickens. The objectives of the study were to conduct a coprological and serological survey on the prevalence of ascaridiosis in laying hens of commercial farms. The farms recently adopted a breeding programme, where the hens have access to outdoor pens. Different amounts of Ascaridia eggs were detected in five of seven studied farms, while the other two farms were found to be free from the parasite. Serological tests revealed a seroprevalence of 21.8% (range 7.6-95%). No positive serum samples were detected in the same farms with previous negative coprological analysis. Western blot analyses confirmed the results obtained by the enzyme-linked immunosorbent assay (ELISA) test. In four experimentally infected hens, a progressive increase of the IgG antibody levels was observed, surpassing the cut-off point established for ELISA test 6 weeks post-infection. Serological tests are able to detect the infection before the eggs of the parasite appear in the faeces of infected hens, providing a useful tool to detect infections with Ascaridia spp. in avian farms.

Specific IgG antibody response against antigens of Dirofilaria immitis and its Wolbachia endosymbiont bacterium in cats with natural and experimental infections.

Sera from three groups of cats under different experimental conditions were studied by ELISA to assess the host's immune response against synthetic peptides derived from Dirofilaria immitis (Dipp) and against the surface protein of its endosymbiont, Wolbachia (WSPr). In experimentally infected cats (Group 1), an increase of IgG antibody against both Dipp and WSPr was observed from 2 months post-infection until the end of the study, 6 months post-infection. In experimentally infected cats, treated against infective larvae (Group 2), anti-Dipp IgG decreased dramatically from 4 months post-infection (3 months post treatment), showing very low values till the end of the study (6.5 months from infection, 5.5 months from treatment), while anti-WSP IgG increased constantly till the end of the study. Of 49 outdoor, asymptomatic cats exposed to a high risk of natural infection (Group 3), 9 were positive for anti-Dipp IgG and for a validated, in-clinic commercial antibody diagnostic kit for cats. Two cats were also found positive for circulating antigens of adult female worm. Anti-WSPr IgG were found in five of nine anti-Dipp IgG-positive sera and from eight ELISADipp-negative sera. Our results confirm the strong IgG response in heartworm infected cats and demonstrate the involvement of the Wolbachia endosymbiont in the immune reaction to the parasite both in experimentally infected cats and in cats exposed to a high risk of natural infection.