Circumvent PCV M - Merck Animal Health

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Diagnostic laboratory survey of porcine circovirus
type 2 and Mycoplasma hyopneumoniae maternallyderived antibodies
A Summary of the Complete Published White Paper.
Brad Thacker, DVM, PhD, DABVP and John Johnson, DVMt
Introduction and Objectives
The objective of this survey was to provide background data for PCV2 and Mhp MDA assessment
for swine operations that are considering vaccination at an early age. In the U.S., nearly all
pigs are vaccinated for porcine circovirus Type 2 (PCV2) and a majority of pigs are vaccinated
for Mycoplasma hyopneumoniae (Mhp). For several reasons, the age of vaccination for these
two diseases has been lowered in a number of swine operations. One factor to consider when
implementing vaccination programs in young pigs is the potential interference of vaccine induced
immune responses by maternally-derived antibodies (MDA).The impact of MDA is expected to
be greater as the age at vaccination declines. In the case of PCV2 vaccination, the impact of
MDA on vaccination effectiveness has not been well studied. The overall impact is believed to be
minor. This survey found that relatively moderate to high levels of MDA had no impact on PCV2
vaccination efficacy (when pigs were vaccinated twice at either 1 and 3, or 3 and 6 weeks of
age1). With Mhp vaccination, previous studies have shown that MDAs have minimal impact on
vaccine efficacy with two injection regimens but may interfere with one injection regimens. With
both diseases, the levels of MDAs and the relative level of vaccine induced immunity needed
to protect the pigs may vary under field conditions. Evaluation of MDA levels in young pigs is
recommended if vaccination at less than 1 week of age is being considered. In many situations,
MDA levels are often not considered because other factors, such as management constraints,
have a greater influence on the desired age at vaccination. The authors encountered several
situations where MDA levels could interfere with vaccination. As a result, evaluation of MDA levels
in young pigs is recommended if early vaccination timing is being considered.
Materials and Methods
This survey includes serum samples from 82 swine operations and several submissions from field
research projects. Table 1 presents sample size and testing information related to the 82 submissions.
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Results
This survey provides background information for the evaluation of PCV2 and Mhp MDA levels.
Thacker and Johnson note that the level of MDAs appears to be a greater concern with Mhp
compared to PCV2. They also explain that the impact of MDA on PCV2 and Mhp vaccination
interference is not well-studied. They recommend that determination of vaccination timing needs
to be performed on a case-bv-case basis using MDA level information, with full consideration
for factors influencing vaccination program implementation and efficacy, and with monitoring of
vaccine efficacy in accordance with changes in vaccination timing.
Discussions
Nearly 42% of the pigs were Mhp seropositive. This situation presented a unique opportunity
to evaluate the virological and production status of pigs experiencing an early infection with
PCV2. Typically, PCV2 infection starts in the late nursery phase of production, after the time of
vaccination at 3 and 6 weeks of age (label directions). In this study, the level of viremia was well
controlled in all vaccinated pigs although the duration of viremia was prolonged in pigs that were
viremic by 6 weeks of age or at the time of the second vaccination.
This survey provides background information for the evaluation of PCV2 and Mhp MDA levels.
Thacker and Johnson note that the level of MDAs appears to be a greater concern with Mhp
compared to PCV2. They also explain that the impact of MDA on PCV2 and Mhp vaccination
interference is not well-studied. They recommend that determination of vaccination timing needs
to be performed on a case-by-case basis using MDA level information, with full consideration
for factors influencing vaccination program implementation and efficacy, and with monitoring of
vaccine efficacy in accordance with changes in vaccination timing.
References
1. Thacker, B, Kniffen, T, Hesse, R, Madson, D, Strait, E. Laboratory Studies on Circumvent® PCV
M: Combination Mycoplasma hyopneumoniae & Porcine Circovirus Type 2 Vaccine In: Proc. 43rd
Annual Meeting of the American Association of Swine Veterinarians, Denver, Colorado, 2012, pp.
123-126.
2. Thacker, B.J., Thacker, E.L Influence of maternally-derived antibodies on the efficacy of a
Mycoplasma hyopneumoniae bacterin. In: Proc. 32nd Annual Meeting of the American Association
of Swine Veterinarians, Nashville, Tennessee, 2001, pp. 513-516.
3. Thacker, B., Wegner, M., Erlandson, K., Maxwell, K., Thompson, J., Thacker, E. Influence of
maternal immunity on Mycoplasma vaccine Respisure-One efficacy. In: Proc. 17th Congress
International Pig Veterinary Society, Ames, Iowa, 2002, p. 307.
4. Hesse, R. Personal communication, 2008.
Table 1 (below) presents sample size and testing information related to the 82 submissions.
Table 1: Number of samples submitted per herd and by test
# of herds
PCV2 IFA only
# of samples
per operation
Both PCV2 IFA and Mhp ELISA
10-19
13
11
1
20-30
28
14
3
>30
8
8
0
Total
49
33
4
Mhp ELISA only
Table 2 (below) presents the PCV2 IFA data by individual pig.
Table 2: PCV2 IFA titer distribution of 2,264 pigs from 82 operations
IFA
titers
% of pigs
<160
160
<160
160
<160
160
66.1
14.0
9.1
5.0
5.9
10.9
Table 3 (below) presents the PCV2 IFA data by operation.
Table 3: Herd distribution by percentage of pigs with PCV2 IFA titers >=640 for 82 operations
% of pigs with
IFA titer >=640
None
1-10%
11-20%
21-40%
>40%
% of
operations
50.0%
22.0%
9.8%
11.0%
8.5%
Table 4 (below) presents the Mhp ELISA data by individual.
Table 4: Mycoplasma hyopneumoniae (Mhp) serostatus of 1,498 pigs from 53 operations
Mhp serostatus
% pf pigs
Positive
41.7%
Negative
58.3%
Table 5 (below) presents the data by operation with regard to the percentage of seropositive pigs
in the submission.
Table 5: Mycoplasma hyopneumoniae (Mhp) herd seropositive rate distribution for 53 herds
Mhp operation
seropositive rate
0%
1-20%
21-40%
41-60%
% of operations
22.6%
22.6%
13.2%
9.4%
61-80%
11.3%
81-99%
100%
9.45%
11.3%

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