The assembly-activating protein promotes capsid assembly of different adeno-associated virus serotypes.

Adeno-associated virus type 2 (AAV2) capsid assembly requires the expression of a virally encoded assembly-activating protein (AAP). By providing AAP together with the capsid protein VP3, capsids are formed that are composed of VP3 only. Electron cryomicroscopy analysis of assembled VP3-only capsids revealed all characteristics of the wild-type AAV2 capsids. However, in contrast to capsids assembled from VP1, VP2, and VP3, the pores of VP3-only capsids were more restricted at the inside of the 5-fold symmetry axes, and globules could not be detected below the 2-fold symmetry axes. By comparing the capsid assembly of several AAV serotypes with AAP protein from AAV2 (AAP-2), we show that AAP-2 is able to efficiently stimulate capsid formation of VP3 derived from several serotypes, as demonstrated for AAV1, AAV2, AAV8, and AAV9. Capsid formation, by coexpressing AAV1-, AAV2-, or AAV5-VP3 with AAP-1, AAP-2, or AAP-5 revealed the ability of AAP-1 and AAP-2 to complement each other in AAV1 and AAV2 assembly, whereas for AAV5 assembly more specific conditions are required. Sequence alignment of predicted AAP proteins from the known AAV serotypes indicates a high degree of homology of all serotypes to AAP-2 with some divergence for AAP-4, AAP-5, AAP-11, and AAP-12. Immunolocalization of assembled capsids from different serotypes confirmed the preferred nucleolar localization of capsids, as observed for AAV2; however, AAV8 and AAV9 capsids could also be detected throughout the nucleus. Taken together, the data show that AAV capsid assembly of different AAV serotypes also requires the assistance of AAP proteins.

[The early recurrence of Crohn's disease after "curative" ileocecal resection. A prospective endoscopic and histological study]. / Frührezidiv des Morbus Crohn nach "kurativer" Ileocoecalresektion. Ein prospektive endoskopische und histologische Untersuchung.

The postoperative course of 44 patients (24 women, 20 men; mean age 31.5 [18-63] years) treated by ileocaecal resection for Crohn's disease was investigated prospectively. None of the patients received any prophylactic drug treatment during the 12-month postoperative period of observation. Recurrence of Crohn's disease was endoscopically diagnosed in 21 of the 44 patients during the 12-month period, and in 14 patients recurrence was suspected. Histological confirmation of recurrent Crohn's disease, however, was obtained unequivocally in only 11 patients, while in further 20 patients there was suspicion of recurrence. A large proportion of the recurrences was already confirmed endoscopically and histologically by the end of the third postoperative month. It is concluded that recurrences are frequent and early after a "curative" operation, raising the question of early prophylaxis with drugs.