Chimaeric plant-produced bluetongue virus particles as potential vaccine candidates.

Bluetongue virus (BTV) causes bluetongue disease in ruminants and sheep. The current live attenuated and inactivated vaccines available for prevention pose several risks, and there is thus a need for vaccines that are safer, economically viable, and effective against multiple circulating serotypes. This work describes the development of recombinant virus-like particle (VLP) vaccine candidates in plants, which are assembled by co-expression of the four BTV serotype 8 major structural proteins. We show that substitution of a neutralising tip domain of BTV8 VP2 with that of BTV1 VP2 resulted in the assembly of VLPs that stimulated serotype-specific antibodies as well as virus-specific neutralising antibodies.

Endogenous folates and single-carbon metabolism in the ovarian follicle, oocyte and pre-implantation embryo.

Maternal B-vitamin status at conception can affect fertility and the health of offspring. This study details transcript expression for genes encoding key enzymes in the linked methionine/folate cycles in the bovine oocyte, somatic cells of the ovarian follicle and pre-implantation embryo. Transcripts for all 12 enzymes that were studied and for the two folate receptors (FOLR1 and FOLR2) and reduced folate carrier (SLC19A1) were expressed in liver cells, but transcripts for betaine-homocysteine methyltransferase and methionine adenosyl transferase 1A were absent in all ovarian cells, and transcripts for FOLR2 were absent in embryonic cells. Transcripts for glycine methyltransferase were also absent/weak in cumulus and granulosa cells. The absence of these enzymes could have a profound effect on single-carbon metabolism within the ovary and pre-implantation embryo. Immunocytochemical analysis revealed SLC19A1 protein expression on the plasma and basal-lateral membranes of the pre-implantation embryo. The folate antagonist methotrexate (MTX) enters the cell via SLC19A1, and in the current study, MTX inclusion in bovine/ovine culture media at either 1 or 10 microM from the 1-cell stage inhibited embryo development beyond the 8-cell stage. Hypoxanthine and thymidine (100 microM) increased the proportion of embryos that developed to blastocysts, but the cell number was reduced by 20%. The reduced uptake of [(35)S] methionine into intra-cellular S-adenosylmethionine and S-adenosylhomocysteine pools, together with reduced uptake of glutamate and tryptophan, was consistent with depleted intra-cellular pools of reduced folates. These data provide an insight into the importance of maternal dietary folate/B-vitamin status during the peri-conceptional period.

Effect of a stabilized stannous fluoride dentifrice on plaque acid (toxin) production.

A Plaque Glycolysis and Regrowth Method (PGRM) has been used to examine the effects of single brushing with a new stabilized stannous fluoride dentifrice on plaque acid production. Plaque samples collected 45 minutes after subject toothbrushing were compared with samples collected prior to toothbrushing for glycolytic activity (pH reduction in incubation media), and the composition and proportion of acids produced during metabolism (capillary electrophoresis). Subjects brushed with both active SnF2 and placebo dentifrices in a cross-over design. Acetic and lactic acid were found to be produced during PGRM metabolism. SnF2 dentifrice was observed to significantly inhibit plaque glycolysis, reducing the pH drop associated with acid production. and specifically inhibiting both lactic acid and acetic acid production. Control dentifrice had a modest inhibitory effect on acid production, primarily inhibiting acetic acid production. SnF2 dentifrice inhibited lactic acid production more effectively than control dentifrice, and this effect appeared to be related to SnF2 specificity in metabolic inhibition, as opposed to the components of control dentifrice, namely ionic fluoride and surfactant. These experimental results support the in vivo antimicrobial activity of SnF2 formulated in a new stabilized matrix (currently marketed as Crest Gum Care), and demonstrate the utility of the PGRM method in elucidating specific mechanisms of action for antimicrobial agents.

Histocompatibility antigen(s) linked to Rfp-Y (Mhc-like) genes in the chicken.

Major histocompatibility complex (Mhc) genes influencing transplantation rejections were first described in mice within the H2 complex and secondly in chickens within the B complex. In chickens, Rfp-Y haplotypes have recently been identified which contain class I and class II Mhc-like genes that assort independently of the B complex. Three Rfp-Y haplotypes have been defined in a closed breeding flock of line N chickens. In this study, progeny were obtained from line N Rfp-Y heterozygous matings to establish the role of Rfp-Y in transplantation immunity. Rfp-Y incompatibility did not induce significant one-way mixed lymphocyte responses. However, Rfp-Y-incompatible skin grafts were rejected more frequently and at a faster rate than Rfp-Y-compatible grafts by two-week-old chicks. The control Mhc B-incompatible grafts were rejected faster than the Rfp-Y-incompatible grafts; the latter were rejected at speeds that resemble rejection of minor histocompatibility antigens. We conclude that Rfp-Y class I and II Mhc-like genes are linked to the expression of minor histocompatibility antigens in chickens.

Infectious mononucleosis complicated by haemolytic anaemia due to the Donath Landsteiner antibody and by severe neutropenia.

A young man developed infectious mononucleosis complicated by profound anaemia due to haemolysis. The Donath Landsteiner antibody was found in his serum. He was treated successfully by blood transfusion but subsequently developed severe neutropenia. Both complications have been reported previously but not in the same individual. No underlying immune deficiency could be identified.