DNA vaccination favours memory rather than effector B cell responses

Following priming and boosting of mice with a DNA vector pEE6ΔS-hCGß expressing sequences encoding a transmembrane version of the β-chain of human chorionic gonadotropin (hCGβ), we failed to detect appreciable levels of specific antibody. However, subsequent challenge with hCG protein in Ribi adjuvant elicited a strong and rapid secondary immune response. This response was of comparable magnitude to that produced following priming, boosting and challenge with protein in adjuvant. Thus, DNA vaccination with this vector is as efficient in generating B cell memory as is conventional immunization, but the memory generation occurs in the absence of an overt effector response. Despite an overall similar level of specific antibody, the DNA-vaccinated mice produced hCG-specific antibodies biased towards IgG2a and IgG2b isotypes, whereas the protein-vaccinated mice produced higher levels of IgG1 antibodies. Both Th1 and Th2 cytokines (interferon-gamma (IFN-γ) and IL-4) were lower in the spleens of the DNA-immunized animals compared with the protein-Ribi-immunized animals, possibly suggesting a different level of helper T cell response to the two different modes of immunization

Epithelial and neuronal calbindin in avian intestine. An immunohistochemical study.

It is well known that calbindin immunoreactivity is highly concentrated in the duodenal absorptive cells of young birds. We have shown that in the adult intestine of three avian species, calbindin content is much more variable. In addition to absorptive cells, we have detected throughout the gut of both sexes of the domestic fowl and in the large intestine of the Japanese quail a second type of calbindin-positive epithelial cell which has the shape of a typical endocrine cell. These cells were particularly abundant in the large intestine, in contrast to the usual distribution of endocrine cells along the gut. Calbindin was also detected in the nervous system of the intestine. Calbindin-positive nerve fibres were rare in the duodenum and ileum, numerous in plexuses and nerve processes in both muscular layers and lamina propria of the large intestine in domestic fowl and Japanese quail. In the mallard, nerve fibres were rarely calbindin positive while definitively positive for VIP. Calbindin of the peripheral nervous system of the domestic fowl and Japanese quail comigrates with the duodenal calbindin (27,000 dalton) in SDS gel electrophoresis.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe