Postnatal Persistent Infection with Classical Swine Fever Virus and Its Immunological Implications

Muñoz-González, Sara; Ruggli, Nicolas; Rosell, Rosa; Pérez, Lester Josué; Frías-Leuporeau, Maria Teresa; Fraile, Lorenzo; Montoya, Maria; Cordoba, Lorena; Domingo, Mariano; Ehrensperger, Felix; Summerfield, Artur; Ganges, Llilianne

To determine whether the inability to clear CSFV was related to a deficient humoral immune response, serum samples from the infected and control pigs were analysed weekly for CSFV-specific antibodies. No detectable antibody response were found in the control pigs (data not shown). Likewise, there were no detectable antibody responses after infection in any of the piglets infected with the Cat01 strain or in the 7 piglets infected with the PR strain that did not clear the virus during the six weeks of the experiment or until death or euthanasia (Fig 4A and 4B ). In contrast, sows infected with the PR and the Cat01 strains are represented in grey and black colours, respectively. Positive results were considered for CT values equal to or less than 42. (d) Detection of CSFV RNA through RT-PCR in the tonsils, thymus and bone marrow are represented in black, grey and white colours, respectively. Positive results were considered for CT values equal or less than 42. An asterisk indicates negative results in pigs 1, 3 and 14 in some of the tissues analysed. Postnatal Persistent Infection of Pigs with CSFV the 3 piglets (#1, 3 and 14) that cleared the PR virus were positive for E2-specific antibodies and virus-neutralising antibodies from 21 days p.i. onwards. The sows were also positive for both binding and neutralising antibodies (Fig 4A and 4B) . Interestingly, the Cat01 virus induced a stronger antibody response than the PR virus in the sows, which again might be related to the higher replication rate of the Cat01 virus.