Impacts of Quarterly Sow Mass Vaccination with a Porcine Reproductive and Respiratory Syndrome Virus Type 1 (PRRSV-1) Modified Live Vaccine in Two Herds

Pedersen, Kasper; Kristensen, Charlotte Sonne; Kvisgaard, Lise Kirstine; Larsen, Lars Erik

doi:10.3390/vaccines9101057

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…Recently, our research group has assessed the prevalence of these multiple PRRSV-vaccinated but ELISA seronegative sows in Belgium; a global prevalence of 3.5% to 4.1% of non-responding sows was found [ 14 ]. Similar observations of anergic sows after repeated PRRSV vaccination were reported at the same time by other research groups, with the global prevalence ranging from 1% to 4% [ 15 , 16 ]. A first consequence of this sow seronegative status for the progeny has been assessed in a follow-up study [ 17 ].…”

Section: Introductionsupporting

confidence: 87%

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (I): Impact on PRRSV-1 Challenge Outcomes in Piglets

Fiers,

Maes,

Cay

et al. 2023

Vaccines

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Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) remains an infectious agent with high importance in the swine industry. In this study, the influence of maternally derived antibodies (MDAs) on an experimental PRRSV-1 challenge is investigated. Piglets included in the study (n = 36) originated from a Belgian farrow-to-finish herd in which the sow population was routinely vaccinated with a modified live vaccine against PRRSV. Eighteen piglets were born from three PRRSV-seropositive sows (responders to vaccination) and had a clear presence of PRRSV-specific MDAs (E+ piglets). The other eighteen piglets were born from three PRRSV-seronegative sows (non-responders to vaccination) and did not have PRRSV-specific MDAs (E− piglets). In each group, twelve piglets were intranasally challenged with a high dose of the heterologous PRRSV-1 07V063 strain, the remaining piglets were mock-challenged (PBS) and served as controls. During the first days after infection, higher serum viremia and nasal shedding were observed in the challenged E− piglets compared to the challenged E+ piglets. However, at 10 days post-infection, the peak serum viremia was significantly higher in the E+ piglets in comparison to the E− piglets and serum viremia remained slightly higher in this group until the end of the study. Additionally, the two challenged groups had a different immune response to the PRRSV infection. The E− challenged piglets showed an earlier and more intense seroconversion, leading to significantly higher antibody titers at 10 dpi compared to the E+ challenged piglets. Furthermore, a trend towards both higher induction of serum IFN-γ and higher induction of IFN-γ secreting cells was observed in the E− challenged piglets. In contrast, a significantly higher induction of serum TNF-α at 7 dpi was seen in the E+ challenged piglets compared to the E− challenged piglets. The results gathered in this study suggest that PRRSV-specific MDAs induce partial protection during the early stages of infection but are not sufficient to protect against a high challenge dose. The presence of piglets lacking PRRSV-specific MDAs might pose a risk for PRRSV infection and enhanced transmission in pig farms in young piglets.

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Section: Introductionsupporting

confidence: 87%

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (I): Impact on PRRSV-1 Challenge Outcomes in Piglets

Fiers,

Maes,

Cay

et al. 2023

Vaccines

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“…One of the boars in the early infected group did not seroconvert after virus exposure, which has previously been described in vaccine trials ( Díaz et al, 2020 ; Pedersen et al, 2021 ). However, this result could also be false negative due to the relative high dilution of the serum in the ELISA or the boar could have had antibodies other than N protein detectable antibodies, e.g., neutralising antibodies.…”

Section: Discussionsupporting

confidence: 51%

Virological and Histopathological Findings in Boars Naturally Infected With Porcine Reproductive and Respiratory Syndrome Virus Type 1

et al. 2022

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Major geographical transmission of porcine reproductive and respiratory syndrome virus (PRRSV) occurs via semen when a boar stud is infected. This happened in Denmark in 2019, providing an opportunity to compare previous experimental PRRSV boar studies with natural PRRSV-1 infection in boars. The aim of this study was to investigate the association between the presence of PRRSV RNA in serum, semen, testicles, and epididymis of boars naturally infected with PRRSV and to describe the histological lesions in the testes and epididymis combined with direct visualisation of PRRSV-infected cells by immunohistochemical staining (IHC). The exact timing of infection of each boar was not determined, but based on serology the boars were divided into two groups: acute and late infections. All boars included were sampled the same day. In this study, 35 boars and 10 healthy boars from another PRRSV-negative boar stud were included as histological controls. PRRSV RNA was found most often in serum (51%) and least frequently in semen (22%) and was more often detected in the reproductive tract in the acute phase of infection (p < 0.0001; RR: 2.58). Mononuclear cells and multinuclear giant cells were present in the adluminal compartment of the testis and epididymis in PRRSV-infected boars, but not in control boars (p < 0.05), which supports the hypothesis that macrophages are involved in the venereal spread of the virus.

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“…Unfortunately, the effectiveness of PRRSV vaccination is suboptimal, mainly due to the large genetic diversity of the virus and its capability to modulate the immune response [ 14 , 15 , 16 ]. Additionally, several studies reported the unsuccessful PRRSV vaccination of both piglets and sows, resulting in seronegative animals despite vaccination [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Our research group aimed to unravel the role of these non-responding animals by assessing their prevalence, origin, and possible consequences [ 26 , 27 , 33 ].…”

Section: Discussionmentioning

confidence: 99%

“…Mainly, the limited production of neutralizing antibodies and the low induction of PRRSV-specific interferon-γ secreting cells are responsible for the lack of protective immunity [ 22 , 23 , 24 , 25 ]. Finally, it has been shown that a proportion of PRRSV-vaccinated sows and/or piglets lack a PRRSV-specific antibody response, with vaccinated pigs remaining seronegative in commercial ELISA kits [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. In multivaccinated sows, the origin of this non-responsiveness upon vaccination remains unknown and warrants further investigation [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (II): Impact on PRRSV-1 Vaccine Effectiveness and Challenge Outcomes in Piglets

Fiers,

Maes,

Cay

et al. 2024

Vaccines

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Vaccination against the Porcine Reproductive and Respiratory Syndrome virus (PRRSV) is widely practiced in both sows and piglets. However, it has been shown that multivaccinated sows sometimes lack a detectable antibody response, testing seronegative in ELISA (non-responders). Moreover, PRRSV-vaccinated piglets can remain seronegative as well, which is mainly attributed to the interference of maternally derived antibodies (MDAs). The current study investigated the impact of the sow’s immune status on the PRRSV vaccine effectiveness in the progeny. The experimental trial included forty-eight piglets (n = 48) originating from a commercial Belgian breeding herd, with twenty-four piglets born from PRRSV vaccinated responder sows (E+ piglets) and twenty-four piglets born from PRRSV vaccinated non-responder sows (E− piglets). Eight piglets in each group were either non-vaccinated (NoVac piglets; n = 8), intramuscularly vaccinated (IM piglets; n = 8), or intradermally vaccinated (ID piglets; n = 8), with the same PRRSV-1 vaccine as used in the sow population. Vaccination was performed at weaning at three weeks of age, and all study piglets were challenged with a high dose of the PRRSV-1 07V063 strain at 6 weeks of age. A clear interference of MDAs was observed in the E+ piglets: 66.7% of the vaccinated E+ piglets lacked an antibody response at 3 weeks post-vaccination (non-responders). Consequently, post-challenge, only the responding E+ piglets had a significantly reduced serum viremia compared to the E+ NoVac piglets. The observed viremia in the non-responding E+ piglets was similar to the viremia of the E+ NoVac piglets. In the vaccinated E− piglets, a lack of antibody response at 3 weeks post-vaccination was observed in 18.8% of the piglets. Interestingly, despite the lack of a vaccine antibody response, the non-responding E− piglets had a significantly reduced serum viremia compared to the NoVac E− piglets. In contrast, the viremia of the responding E− piglets was only numerically reduced compared to the NoVac E− piglets. Finally, some clear differences were observed in both the kinetics of infection and the immune responses post-challenge between the E+ and E− piglets. The results of this study confirm the consequences of the MDA interference on the induced partial protection of PRRSV vaccination in experimentally challenged piglets. More research is warranted to understand the immunological mechanisms behind MDA interference in PRRSV vaccination and to explain the observed differences between E+ and E− piglets.

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Impacts of Quarterly Sow Mass Vaccination with a Porcine Reproductive and Respiratory Syndrome Virus Type 1 (PRRSV-1) Modified Live Vaccine in Two Herds

Cited by 4 publications

References 28 publications

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (I): Impact on PRRSV-1 Challenge Outcomes in Piglets

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (I): Impact on PRRSV-1 Challenge Outcomes in Piglets

Virological and Histopathological Findings in Boars Naturally Infected With Porcine Reproductive and Respiratory Syndrome Virus Type 1

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (II): Impact on PRRSV-1 Vaccine Effectiveness and Challenge Outcomes in Piglets

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