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Production of a murine IgG1 was investigated using hairy roots, shooty teratomas, and suspended cells of transgenic tobacco. In all cases, in addition to complete assembled antibody, two to four major antibody fragments accumulated in the biomass. A range of protease inhibitors, protein-stabilizing agents, inhibitors of N-glycosylation and protein secretion, glycan-reactive agents, and affinity probes was used to characterize these fragments and investigate their sites and mechanisms of formation. The fragments were not experimental artifacts caused by antibody degradation during tissue homogenization and sample preparation, nor did they represent glycosylation variants. All of the molecules were actively secreted into the culture media and some showed evidence of Golgi-associated glycan processing, indicating they were not assembly intermediates. Antibody fragments of 50 and 80 kDa were identified mainly as the products of extracellular degradation in the root and shoot apoplast; the 80-kDa fragment was also present in cell suspension medium, and in suspended cell biomass toward the end of the growth phase. Larger 120- and 135-kDa fragments were most likely produced by proteolytic degradation along the secretory pathway outside of the endoplasmic reticulum (ER) and Golgi apparatus; the carbohydrate residues of the 135-kDa antibody suggest formation between these organelles. Inhibition of protein secretion and retention of antibody in the ER and/or Golgi reduced fragmentation and increased antibody accumulation levels, probably by reducing exposure to the principal sites of protease activity. This work highlights the importance of foreign protein degradation in plant tissues as a mechanism for posttranslational product loss. Identifying the nature of these degradative processes is a first step toward alleviating their effects, improving protein yields, and enhancing the feasibility of plants as a commercial means for large-scale protein production., (Copyright 2001 John Wiley & Sons, Inc.)

Vaccination of pregnant ewes with a Pasteurella haemolytica adjuvanted vaccine which contained serotypes A1, A2 and A6 antigens caused significant increases in serum antibody titres to A1 and A6 measured by the indirect haemagglutination test (IHA). The response to vaccination with the serotype A2 antigen contained in this vaccine cannot be measured by the IHA test. There were also increased antibody titres in the colostrum from the vaccinated ewes and in the serum of their lambs after sucking compared with the corresponding titres in unvaccinated ewes and their lambs. The inoculation of either 10 +/- 2- or 18 +/- 2-day-old lambs from both vaccinated or unvaccinated ewes with the same vaccine induced the active production of antibodies to serotypes A1 and A6 despite the presence of passively acquired antibodies. By four weeks after vaccination the group geometric mean serum antibody titres of lambs from both vaccinated and unvaccinated were similar whether the lambs were vaccinated at 10 or 18 days of age. Successful vaccination of young lambs with this type of vaccine is therefore possible. Optimum protection would be obtained by vaccinating ewes in late pregnancy and their lambs within the first two weeks of life.

Two groups of 10, specific pathogen free lambs were injected with a long acting oxytetracycline preparation at a dose rate of 20 mg/kg either 24 hours before or 24 hours after exposure to an aerosol of Pasteurella haemolytica. When compared with the response of similarly infected but untreated lambs, the effect of pretreatment was to postpone the appearance of clinical signs of pneumonia for four days and the deaths of five lambs for five to six days post infection, by which time seven untreated lambs had died. Treatment 24 hours after infection caused a rapid clinical recovery which persisted until six days after infection but two treated lambs died seven days after infection. Lung lesions in the group treated after infection were significantly less extensive than those in the untreated lambs.

The efficacy of a multicomponent clostridial vaccine containing Pasteurella haemolytica antigens was tested in specific pathogen free or conventionally reared lambs exposed to experimental infection with P haemolytica serotypes A1, A2 or A6. In four experiments assessment was based upon the findings of clinical, pathological and bacteriological examinations. Three experiments carried out in conventionally reared lambs demonstrated protection against challenge infection with P haemolytica serotypes A1, A2 and A6 in vaccinated lambs. However, the inconsistency of the disease induced in these experiments emphasised the need to perform definitive studies in specific pathogen free conditions. The final experiment was carried out with specific pathogen free lambs and confirmed the efficacy of the multicomponent clostridial vaccine containing P haemolytica antigen in protecting against the effects of infection with P haemolytica serotype A6. In addition, this experiment indicated that the inclusion of several components in a vaccine did not affect the efficacy of an individual antigenic component.

Virus particles, morphologically indistinguishable from maedi-visna virus or caprine arthritis-encephalitis virus, were detected in tissue explant cultures prepared post mortem from a goat with joint, lung and kidney lesions similar to those associated with the caprine arthritis-encephalitis complex. Serum from this goat and others in its herd of origin gave positive reactions in an agar gel immunodiffusion test for maedi-visna virus antibodies.