Quantitation by ELISA of pili and sheep antibodies to the pili of Bacteroides nodosus

ELISA systems have been developed to quantitate the isotypic antibody response of sheep naturally infected with B. nodosus isolate 198 or injected with pili from isolate 198 in oil emulsion vaccines. The predominant humoral antibody detected following vaccination was IgG1, with substantially lower amounts of IgG2 and IgM. The antibody response was relatively specific for the pilus antigen from isolate 198. Although weak cross reactivities were detected with antiserums to some other isolates, ELISA IgG antibody titres in excess of 200 offer a tentative identification of the isolates of B. nodosus involved in natural outbreaks of footrot. A related ELISA was also developed to quantitate the amount of pili in cell suspensions and crude preparations of pili used in vaccines.     

Separation of serum antibody activities by anion-exchange cellulose chromatography

Mumps, Histoplasma capsulatum. thyroglobulin, and typhoid H antibodies were found in fraction 1, which contained only gamma globulins with ultracentrifugal sedimentation coefficients of 6.6 Svedberg units (S). Typhoid O antibodies and rheumatoid factor were only in fraction 5, composed principally of gamma macroglobulins with ultracentrifugal sedimentation coefficients of 18 S. In contrast isohemagglutinins, Rh antibodies, and anti-human liver nucleoprotein activities were found in two chromatogram fractions (1 and 5) with different physicochemical properties.     

Nutrient Accumulation in Vegetation Following Conventional and Whole-Tree Harvest of Sitka Spruce Plantations in North Wales

The role of regrowing vegetation in buffering nutrient lossesfollowing whole-tree and conventional harvest of Sitka sprucewas examined at Beddgelert Forest in North Wales. Biomass andnutrient accumulation were about twice as rapid on the whole-tree(WH) than the conventional harvest (CH) plots, apparently becauselogging residue shaded the ground on the CH plots. This resultprobably helps to explain much higher leaching of nutrientsfrom the root zone on the CH than the WH plots. However, thedifferences in nutrient accumulation in regrowing vegetationbetween WH and CH plots were much smaller than the differences(in the opposite direction) in nutrient removal of forest products.Thus, higher nutrient accumulation in regrowing vegetation followingWH compared with CH may partly counteract leaching losses duringthe first few years but this effect is clearly outweighed bythe higher nutrient removal in forest products in WH.     

Assessment by ELISA of passively acquired protection against infectious bursal disease virus in chickens

The level of maternal antibody to infectious bursal disease (IBD) virus in the circulation of one-day-old layer strain chickens was found to be on average, 45% of the antibody titre in their respective dam, while the minimum ELISA titre which protected against a challenge of 1000 CID50 of virus was 400. Maternal antibody was found to disappear from the circulation of these crossbred chickens with a half-life of 6.7 days. From these data it is possible to estimate the ELISA titre necessary in vaccinated hens to provide the desired duration of passive protection; protection being assessed by an ELISA which measures IBD viral antigen in the bursa of Fabricius following challenge.