Botulinum neurotoxins (BoNT) are some of the most toxic proteins known, with a human LD50 of ~1 ng/kg. Equine antitoxin has a half-life in circulation of less than 1 day and is limited to a treatment rather than a prevention indication. The development of monoclonal antibodies (mAbs) may represent an alternative therapeutic option that can be produced at high quantities and of high quality and with half-lives of >10 days. Two different three mAb combinations are being developed that specifically neutralize BoNT serotypes A (BoNT/A) and B (BoNT/B). We investigated the pharmacokinetics of the anti-BoNT/A and anti-BoNT/B antibodies in guinea pigs (Cavia porcellus) and their ability to protect guinea pigs against an aerosol challenge of BoNT/A1 or BoNT/B1. Each antibody exhibited dose-dependent exposure and reached maximum circulating concentrations within 48 h post intraperitoneal or intramuscular injection. A single intramuscular dose of the three mAb combination protected guinea pigs against an aerosol challenge dose of 93 LD50 of BoNT/A1 and 116 LD50 of BoNT/B1 at 48 h post antibody administration. These mAbs are effective in preventing botulism after an aerosol challenge of BoNT/A1 and BoNT/B1 and may represent an alternative to vaccination to prevent type A or B botulism in those at risk of BoNT exposure.

Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. BoNTs are also classified as tier 1 biothreat agents due to their high potency and lethality. The existence of seven BoNT serotypes (A to G), which differ by 35% to 68% in amino acid sequences, necessitates the development of serotype-specific countermeasures.

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Worldwide Colletotrichum spp. have been identified as a problem in the apple production. This is the first study executed and confirming the presence of Colletotrichum spp. causing the postharvest disease bitter rot on apple fruits in Belgium. The identification, genetic diversity of Colletotrichum isolates (present in Belgian apple orchards) their morphological traits and pathogenicity on two apple cultivars (cvs. Pinova and Nicoter) with a different level of susceptibility were studied. Based on sequence analysis of six different gene regions beta-tubuline (TUB2), histone H3 (HIS3), glyceraldehyde-3phosphate dehydrogenase (GAPDH), chitin synthase 1 gene (CHS-1), actin (ACT) and the Internal Transcriber Spacer (ITS) gene region, six different Colletotrichum spp., belonging to either the C. acutatum or C. gloeosporioides complexes, were isolated from twenty-one apple cultivars in three Belgian orchards: C. fioriniae, probably C. kahawae, C. salicis, C. rhombiforme, C. acutatum and C. godetiae. Colletotrichum godetiae was found to be the most present and pathogenic species in Belgian orchards. The species C. rhombiforme was found and identified on apple fruit for the first time. Reliable morphological discrimination between species, based on features such as in vitro growth rate, colony colour and spore measurements, is not possible. As such, molecular identification appears to outperform morphological analysis and was in this study the most ideal tool for identifying unknown isolates of Colletotrichum species. Inoculation assays on two apple cultivars revealed a significant difference in pathogenicity among isolates and among Colletotrichum species. The pathogenicity tests also showed that isolates coming from another host species, e.g. strawberry, are also pathogenic on apple fruits. Cultivar Pinova appeared to be more susceptible to bitter rot than cv. Nicoter. Given the difficulties with managing Colletotrichum infections, additional knowledge on the pathogen and the plant-pathogen interaction is essential for effective disease control.

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