Biomedical subjects

Roland Maurer

Publications and source records attributed to Roland Maurer.

3 recordsLinked to original sources

PubMed2005

Oronasal vaccination with classical swine fever virus (CSFV) replicon particles with either partial or complete deletion of the E2 gene induces partial protection against lethal challenge with highly virulent CSFV.

A cDNA clone of the classical swine fever virus (CSFV) strain Alfort/187 [Ruggli N, Tratschin JD, Mittelholzer C, Hofmann MA. Nucleotide sequence of classical swine fever virus strain Alfort/187 and transcription of infectious RNA from stably cloned full-length cDNA. J Virol 1996;70(6):3478-87] was used to construct two E2 deletion mutants lacking either the complete E2 gene or, alternatively, a stretch of 204 nucleotides encoding 68 amino acids located in the C-terminal region of the E2 glycoprotein. The respective in vitro synthesized mutant RNAs replicated in SK-6 cells but no infectious virus was generated. Both replicons could be packaged into virus particles in SK-6 cells constitutively expressing E2 of CSFV. For the resulting CSF virus replicon particles (CSF-VRP) A187-E2del373 and A187-E2del68 titers of 10(6) and 10(7) TCID(50)/ml, respectively, were obtained. Oronasal vaccination with 10(7) TCID(50) of either of the two CSF-VRP protected pigs against a challenge with a lethal dose of CSFV strain Eystrup. In contrast, after intradermal vaccination VRP A187-E2del68 but not VRP A187-E2del373 lacking the complete E2 gene induced a protective immune response. We conclude that E2-complemented CSF-VRP have the potential to be used as live-attenuated non-transmissible oral vaccines for pigs. In addition, our data suggest that E2 of CSFV is dispensable for the induction of mucosal but not of parenteral immunity.

Administration, Intranasal↗

PubMed2004

Resetting the path integrator: a basic condition for route-based navigation.

During short excursions away from home, some mammals are known to update their position with respect to their point of departure through path integration (dead reckoning) by processing internal (idiothetic) signals generated by rotations and translations. Path integration (PI) is a continuously ongoing process in which errors accumulate. To remain functional over longer excursions, PI needs to be reset through position information from stable external references. We tested the homing behaviour of golden hamsters (Mesocricetus auratus W.) during hoarding excursions following a rotation of the arena and nest. In continuous darkness, the hamsters returned to their point of departure at the rotated nest, and therefore depended on PI only. In other trials, the animals were briefly presented with visual room cues during or at the end of the outward trip, visual cues being pitted by 67 degrees or 98 degrees against the animal's current self-generated position vector. After a fix, the animals headed for the usual (unrotated) nest location, as defined by room cues, independent of the timing of the fix. These results were obtained in two different geometrical settings and showed that, after the fix, the animals update their position, and not merely their head direction or internal compass, in a new reference frame. Thus, episodic fixes on familiar external references reset the PI and therefore greatly enhance the functional signification of navigation that is based on feedback information from locomotion.

Animals↗

PubMed2003

Voles scale locomotion to the size of the open-field by adjusting the distance between stops: a possible link to path integration.

In this study we show that social voles (Microtus socialis guentheri) preserve the same level of activity and spatio-temporal organization of behavior whether exploring a small (1 x 1 m) or a large (2 x 2 m) open field. In each open field, a vole established a home base from which it set on to round-trips of exploration; taking fewer but longer trips in the large open field, compared with more frequent but shorter trips in the small open field. Each trip comprised bouts of progression (locomotion) interrupted by stops. The number of stops per trip was the same for both large open field (longer trips) and small open field (shorter trips), and achieved by scaling the distance between stops according to the size of the open field. Voles traveled more along the walls in the large compared with the small open field. These adjustments in locomotor behavior to open field size were observed immediately after the voles were introduced into the arena, indicating that the perceived distances available for locomotion were identified by the voles immediately at the beginning of exploration. It is suggested that these properties of spontaneous exploration are an expression of navigation using visual landmarks and path integration.

Animals↗