E2 and Erns isotype-specific antibody responses in serum and oral fluid after infection with classical swine fever virus (CSFV).

Oral fluid sampling for the detection of classical swine fever virus infection provides a relatively inexpensive method for conducting active CSF surveillance. The purpose of this study was to detect CSFV nucleic acid and antibody in serum and oral fluid samples in a group of 10 pigs infected with the moderate CSFV strain, Paderborn. Based on clinical signs, outcome, and other results, pigs were placed into one of three disease outcome groups; Acute, Chronic and Recovered. Oral fluid and serum samples were analyzed for the presence of CSFV nucleic acid along with E2 and Erns surface protein-specific IgM, IgG and IgA responses. The results were summarized into a timeline of detection events beginning with the appearance of E2-IgM in serum (3 DPI) followed by CSFV nucleic acid in serum (6 DPI), CSFV nucleic acid in oral fluid (8 DPI), E2-IgG in serum (20 DPI), and E2-IgG in oral fluid (24 DPI). The results show that a combination of molecular and serological analyses of oral fluid can be incorporated into CSF surveillance.

Knockout of maternal CD163 protects fetuses from infection with porcine reproductive and respiratory syndrome virus (PRRSV).

After infection of the porcine dam at about 90 days of gestation, porcine reproductive and respiratory syndrome virus (PRRSV) crosses the placenta and begins to infect fetuses. Outcomes of include abortion, fetal death and respiratory disease in newborn piglets. CD163 is the receptor for the virus. In this study, CD163-positive fetuses, recovered between 109 days of gestation or 20 days after maternal infection, were completely protected from PRRSV in dams possessing a complete knockout of the CD163 receptor. The results demonstrate a practical means to eliminate PRRSV-associated reproductive disease, a major source of economic hardship to agriculture.

GP5 of porcine reproductive and respiratory syndrome virus (PRRSV) as a target for homologous and broadly neutralizing antibodies.

Virus neutralization (VN) responses range from narrowly focused antibodies with only homologous neutralizing activity against the virus used for infection, to antibodies that can neutralize both Type 1 and Type 2 viruses, referred to as broadly neutralizing antibody (bnAb). Even though neutralizing epitopes are likely distributed among several structural glycoproteins, this paper focuses on the ectodomain region of GP5 as a model system for investigating the role for neutralizing and non-neutralizing antibodies in protection and disease. Epitope B within GP5 possesses several features common to broadly neutralizing epitopes. In the proposed model, accessibility of antibody to Epitope B is blocked by homologous neutralizing and non-neutralizing antibodies, which bind flanking hypervariable domains. Additional mechanisms for blocking the accessibility of bnAb include conformational alterations within the GP5-M heterodimer and glycan shielding. This model explains how the continuous escape from homologous neutralization provides a mechanism for persistence. The proposed mechanism for immune evasion is not unique to PRRSV, but can be found in other persistent viruses, such as hepatitis C virus (HCV).

A single amino acid deletion in the matrix protein of porcine reproductive and respiratory syndrome virus confers resistance to a polyclonal swine antibody with broadly neutralizing activity.

Assessment of virus neutralization (VN) activity in 176 pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV) identified one pig with broadly neutralizing activity. A Tyr-10 deletion in the matrix protein provided escape from broad neutralization without affecting homologous neutralizing activity. The role of the Tyr-10 deletion was confirmed through an infectious clone with a Tyr-10 deletion. The results demonstrate differences in the properties and specificities of VN responses elicited during PRRSV infection.