KVÄLLSSYMPOSIUM 2008 Vaccinering av hund och katt

272 S.M. Moore et al. / Biologicals 33 (2005) 269e276
Fig. 2. Amino acid alignment of the rabies glycoprotein from Flury, CVS and PM strains (courtesy of Dr Iris Stalkamp, Institut fu¨r Virologie,
Giessen, Germany). There are fewer amino acid sequence changes from CVS to PM (filled arrows) than CVS to Flury (open arrows). The changes are
not in areas of the mapped antigenic sites of the rabies glycoprotein (shaded triangles). The transmembrane sequence is indicated by the boxed area.
eliminate the need to calculate international units using
titer results obtained from an international rabies
reference serum that originated from subjects only
vaccinated with a rabies vaccine produced from a PM
seed strain of rabies virus.
2.5. Statistical analyses
After all serum samples were tested separately with
both the CVS-11 and the Flury-LEP rabies challenge
virus strains, the identification of the two vaccination
groups (PVRV and PCECV) was unblinded and the
RVNA titers were statistically analyzed to determine the
effect of serological testing by means of a homologous
vs. heterologous test. To determine whether any straindependent
difference in neutralizing antibody was
magnified at higher titers, the titer results (both day 14
and day 90) were sorted into response groups, the
geometric mean titer (GMT) of the groups was
calculated, and the GMT by challenge virus was
compared. Additionally, to determine whether maturation
of the antibody response amplified the differences in
GMT, the titer responses by day of serum drawn were
sorted and the GMT of the groups was calculated and
compared by challenge virus.
3. Results
The virus titer of CVS-11 and Flury-LEP, used as the
challenge virus in each of the five serological testing
groups, remained consistently equivalent throughout the
testing period (Table 1). There was a similar wide range
of RVNA titers obtained for each vaccination group,
independent of whether CVS-11 or Flury-LEP was used
as the challenge virus strain (Table 2). There were two
outlier reciprocal titer values in the PVRV vaccination
group, 9500 and 19 700, exhibited by the same subject