KVÄLLSSYMPOSIUM 2008 Vaccinering av hund och katt

Table 1
Titer of Challenge Virus Standard (CVS-11) and Flury low egg passage
(Flury-LEP), the two rabies virus strains used as the challenge viruses
for each serological testing group
Serological testing group Titer of CVS-11 Titer of Flury-LEP
1 42.1 41.1
2 40.0 41.2
3 41.0 40.0
4 41.4 42.3
5 41.1 40.9
Geometric mean 41.1 41.1
Virus titer is expressed in TCID50. on days 14 and 90, respectively. The GMT for each
group indicates higher RVNA titers were reported when
a homologous challenge virus strain was used in the
serological assay. The RVNA test results of individual
serum samples indicated that there was a clear trend to
report higher titers when a homologous testing system
(CVS-11 used as the challenge virus in the RFFIT for
testing sera from subjects vaccinated with PVRV and
Flury-LEP used as the challenge virus in the RFFIT for
testing sera from subjects vaccinated with PCECV)
rather than a heterologous testing system (Flury-LEP
used as the challenge virus in the RFFIT for testing sera
from subjects vaccinated with PVRV and CVS-11 used
as the challenge virus in the RFFIT for testing sera from
subjects vaccinated with PCECV) was used (Fig. 3).
The RVNA values in both the PCECV and the
PVRV vaccine groups included titers in the low, medium
and high range, regardless of which challenge virus was
used in the assay. Low, medium, and high ranges were
designated for this set of results to determine possible
trends associated with the strength of the antibody
response. Nearly two-thirds of the samples from each
Table 2
Rabies virus neutralizing antibody (RVNA) titers from the Rapid
Fluorescent Focus Inhibition Test (RFFIT) using a homologous
challenge virus testing system and a heterologous challenge virus
testing system
Vaccine RFFIT testing GMT (range)
administered system
Challenge virus Day 14 Day 90
PCECV Homologous 1855 265
Flury-LEP (320e6300) (45e1500)
Heterologous 1275 183
CVS-11 (145e5400) (45e1100)
PVRV Homologous 2364 274
CVS-11 (360e8500) (45e9500)
Heterologous 1448 188
Flury-LEP (70e8500) (45e19700)
Serum samples were obtained from subjects vaccinated with purified
chick embryo cell rabies vaccine (PCECV) or purified Vero cell rabies
vaccine (PVRV) and were assayed using CVS-11 and Flury-LEP as the
challenge viruses in the RFFIT.
S.M. Moore et al. / Biologicals 33 (2005) 269e276
titers (Flury) log dil
4.00
3.50
3.00
2.50
2.00
1.50
1.50 2.00 2.50 3.00 3.50 4.00
vaccine group reported higher titers when a homologous
challenge virus strain was used for the RFFIT assay,
63% for PCECV and 65% for PVRV. Approximately
30% of the serum samples tested in each vaccine group
reported titers that were the same value or similar
(within one standard deviation) regardless of whether
they were assayed using a homologous or a heterologous
challenge virus strain.
The percent reduction of reported RVNA titers,
when switching from a homologous testing system to
a heterologous testing system was 23%, 47%, and 33%,
respectively, for the low, medium, and high response
groups in the PVRV vaccination group and 27%, 25%,
and 40% in the PCECV vaccination group (Fig. 4).
Thus, there was no clear trend of higher or lower RVNA
titers related to the type of testing system, and whether
the serum tested belonged to the low, medium, or high
response group. The overall reduction in RVNA titer
values when switching from a homologous challenge
virus assay to a heterologous challenge virus assay was
33% for the PVRV vaccination group, and a 31%
reduction for the PCECV vaccination group.
On both day 14 (data not shown) and day 90 the
GMTs were higher when a homologous challenge virus
system was used for the PVRV and PCECV vaccination
groups (Fig. 5).
4. Discussion
PCECV Subjects PVRV Subjects
titers (CVS) log dil
Fig. 3. Serum samples from day 90 after administration of purified
chick embryo cell rabies vaccine (PCECV) or purified Vero cell rabies
vaccine (PVRV) given in a post-exposure prophylaxis regimen were
analyzed twice by RFFIT. In one assay CVS-11 was utilized as the
challenge virus in the RFFIT and in the second RFFIT, Flury-LEP
was utilized as the challenge virus. The rabies virus neutralization titer
(RVNA) result obtained for each serum sample was plotted according
to the challenge virus used in the RFFIT. The line of unity represents
expected RFFIT values that would be equivalent regardless of whether
CVS-11 or Flury-LEP rabies virus was used as the challenge virus for
patients vaccinated with PCECV or PVRV. Similar results were seen
with the day 14 results (data not shown).
Neutralizing antibodies play a critical role in immune
protection against rabies infection. Therefore, it is
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