Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Xiuqing Wang


2', 3' -cGAMP, adjuvant, intranasal, PRRSV, viremia, virus-like particle


Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically devastating virus that causes a persistent infection and spreads quickly. The virus causes abortions in sows and respiratory diseases in young piglets. Current PRRSV vaccines appear to provide limited cross-protection. A virus-like particles (VLPs) vaccine is made up of key PRRSV structural proteins, which could be cross protective among the different strains. We tested PRRSV VLPs as a vaccine candidate with a 2’, 3’-cGAMP VacciGradeTM adjuvant against pigs infected with PRRSV after intranasal immunization to evaluate the immune response and protective efficacy by the VLPs and adjuvant. The VLPs contain PRRSV nucleocapsid (N), glycoprotein 5 (GP5), membrane (M), and the envelope (E) proteins. There were 3 groups of pigs vaccinated with PBS for a control group, a VLPs group, and VLPs group with the 2’3’-cGAMP adjuvant. Vaccination occurred once initially and again as a boost after 2 weeks. Challenge with PRRSV occurred 2 weeks post boost. At 0 days post challenge (DPC), no GP5 or N PRRSV antibodies were found in all animal groups, although N PRRSV antibodies were detected in all groups at 10 DPC. The adjuvant group demonstrated a significantly increased viremia at 7 and 10 DPC likely due to its ability to enhance the innate immune response and bring more immune cells for the virus to target. Interferon-alpha concentrations were also higher in the VLPs with adjuvant group, but there was only a slight increase in IL-10 and interferon-gamma. The VLPs with adjuvant group showed a significant increase in VLP specific IgG and IgA at 7 DPC when compared to 3 DPC, but they did not reduce viremia. To further test the VLPs as a vaccine candidate, different PRRSV proteins should be incorporated into the VLPs assembly and other routes of vaccination could be considered such as intramuscular injection. A higher dosage of the VLPs could also be tested.

Library of Congress Subject Headings

Porcine reproductive and respiratory syndrome.
Immune response.
Swine -- Virus diseases.
Viral vaccines.


Includes bibliographical references (pages 39-53)



Number of Pages



South Dakota State University



Rights Statement

In Copyright