Healthy piglet protected by a glowing immunity shield.

Boosting Swine Health: How Saponin Quil A Enhances PRRSV-1 Vaccine Efficacy

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Rhea Morgan in Health & Wellness June 2025 • 4 min read.

"Explore how combining saponin Quil A with a modified-live virus vaccine can revolutionize the fight against Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)."


Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) continues to be a significant economic threat to the swine industry worldwide. Characterized by reproductive failures in breeding stock and respiratory distress in growing pigs, PRRSV's impact is far-reaching and demands innovative solutions.

Traditional modified-live virus (MLV) vaccines have shown promise, but their effectiveness can be variable, particularly against heterologous strains of PRRSV. The key to successful PRRSV control lies in inducing a robust and cross-protective immune response. The challenge is that currently available PRRSV MLV vaccines often elicit delayed and weak immune responses, necessitating the exploration of adjuvants to boost their efficacy.

In a recent study, researchers investigated the potential of saponin Quil A, a natural compound known for its immunostimulatory properties, to enhance the protective immunity of a PRRSV-1 MLV vaccine against a PRRSV-2 challenge. The findings shed light on novel strategies for improving vaccine efficacy and offer new avenues for combating this pervasive swine disease.

Quil A: A Powerful Adjuvant to Enhance PRRSV Vaccine Response?

Healthy piglet protected by a glowing immunity shield.

The study, conducted at Maejo University in Thailand, involved twenty-four 4-week-old PRRSV-seronegative pigs divided into four groups. Groups 1 and 2 were vaccinated with a PRRSV-1 MLV vaccine. Additionally, Group 2 received intramuscular injections of Quil A. Group 3 was injected with the vaccine solvent as a challenge control, while Group 4 served as a strict control. At 28 days post-vaccination, Groups 1-3 were challenged intranasally with PRRSV-2, and immune and clinical parameters were observed over 49 days.

The results demonstrated that Group 1, vaccinated with PRRSV-1 MLV alone, showed a significant reduction in PRRSV viremia, a lower number of viremic pigs, improved clinical scores, and enhanced average daily weight gain (ADWG) compared to the challenge control group. These outcomes highlight the inherent protective capabilities of the PRRSV-1 MLV vaccine.

  • Enhanced Gene Expression: Group 2, which received Quil A alongside the vaccine, exhibited significantly increased mRNA expressions of key immune factors, including interferon regulatory factor 3 (IRF3), 2'-5'-oligoadenylatesynthetase 1 (OAS1), osteopontin, IFNa, IFNẞ, IFNy, interleukin-2 (IL-2), IL-13, and tumor necrosis factor alpha (TNFa), compared to Group 1.
  • Reduced Viremia: These animals also demonstrated significantly reduced PRRSV viremia and fewer viremic pigs, indicating a stronger immune response.
  • No Additional Improvement in Antibody Levels: Interestingly, Group 2 did not show further improvements in PRRSV-specific antibody levels, neutralizing antibody titers, rectal temperature, clinical scores, or ADWG compared to Group 1.
These findings suggest that Quil A's primary impact lies in up-regulating the expression of type I interferon-regulated genes, type I and II interferons, and inflammatory cytokines, which synergize with the PRRSV-1 MLV vaccine to further reduce PRRSV viremia and the number of viremic pigs. This positions Quil A as a promising immunostimulator for potentiating cell-mediated immune defense against PRRSV.

Implications and Future Directions

The study's findings indicate that Quil A holds significant potential as an effective immunostimulator for enhancing cell-mediated immunity against PRRSV. Further research is needed to fully elucidate the mechanisms by which Quil A modulates the immune response and to optimize its use in PRRSV vaccine strategies. However, the results offer a promising step forward in the ongoing effort to develop more effective and cross-protective PRRSV vaccines, ultimately benefiting the swine industry by reducing the economic losses associated with this devastating disease.

About this Article -

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Everything You Need To Know

1

What is Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and why is it a problem?

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is a significant economic threat to the swine industry. It causes reproductive failures in breeding stock and respiratory distress in growing pigs, leading to substantial losses worldwide. The virus's ability to cause such widespread issues necessitates the development of effective control measures like vaccines.

2

How do traditional modified-live virus (MLV) vaccines for PRRSV perform, and what's the challenge?

Traditional modified-live virus (MLV) vaccines for PRRSV have shown some promise, but their effectiveness can be variable, especially against different strains of the virus (heterologous strains). The primary challenge is inducing a robust and cross-protective immune response. Often, these vaccines elicit delayed and weak immune responses, making it necessary to explore adjuvants to boost their efficacy.

3

What role does Saponin Quil A play in enhancing the immune response to a PRRSV-1 MLV vaccine?

Saponin Quil A acts as an immunostimulator, enhancing the protective immunity of a PRRSV-1 MLV vaccine. When used with the vaccine, Quil A significantly increases the mRNA expressions of key immune factors, including interferon regulatory factor 3 (IRF3), 2'-5'-oligoadenylatesynthetase 1 (OAS1), osteopontin, IFNa, IFNẞ, IFNy, interleukin-2 (IL-2), IL-13, and tumor necrosis factor alpha (TNFa). This upregulation leads to a stronger immune response, reducing PRRSV viremia and the number of viremic pigs when challenged with PRRSV-2.

4

What were the key findings of the study on Quil A and the PRRSV-1 MLV vaccine conducted at Maejo University?

The study showed that pigs vaccinated with the PRRSV-1 MLV vaccine and Quil A exhibited significantly increased mRNA expression of crucial immune factors. This group also demonstrated significantly reduced PRRSV viremia and fewer viremic pigs. Although no additional improvements were observed in PRRSV-specific antibody levels or average daily weight gain (ADWG), the results highlight Quil A's primary impact on up-regulating the expression of type I interferon-regulated genes and inflammatory cytokines, enhancing cell-mediated immune defense against PRRSV.

5

What are the implications of using Quil A in PRRSV vaccine strategies, and what future research is needed?

The study's findings suggest that Quil A is a promising immunostimulator for enhancing cell-mediated immunity against PRRSV. The results offer a promising step forward in developing more effective and cross-protective PRRSV vaccines. Further research is needed to fully understand the mechanisms by which Quil A modulates the immune response and optimize its use in PRRSV vaccine strategies, ultimately benefiting the swine industry by reducing economic losses associated with this disease.

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