Positive selection pressure on E2 protein of classical swine fever virus drives variations in virulence, pathogenesis and antigenicity : implication for epidemiological surveillance in endemic areas

• Classical swine fever (CSF), caused by CSF virus (CSFV), is considered one of the most important infectious diseases with devasting consequences for the pig industry. Recent reports describe the emergence of new CSFV-strains resulting from the action of positive selection pressure, due mainly to the bottleneck effect generated by ineffective vaccination. Even though a decrease in the genetic diversity of the positive selected CSFV-strains has been observed by several research groups, there is little information about the effect of this selective force on the virulence degree, antigenicity and pathogenicity of this type of strains. Hence, the aim of the current study was to determine the effect of the positive selection pressure on these three parameters of CSFV-strains, emerged as result of the bottleneck effects induced by unproper vaccination in a CSF-endemic area. Moreover, the effect of the positive selected strains on the epidemiological surveillance system was assessed. By the combination of in vitro, in vivo and immunoinformatic approaches we revealed that the action of the positive selection pressure induces a decrease in virulence and alteration in pathogenicity and antigenicity. However, we also noted that the evolutionary process of CSFV, especially in segregated microenvironments, could contribute to the gain-fitness event, restoring the highly virulent pattern of the circulating strains. Besides, we denoted that the presence of low virulent strains selected by bottleneck effect after inefficient vaccination can lead to a relevant challenge for the epidemiological surveillance of CSF, contributing to under-reports of the disease, favoring the perpetuation of the virus in the field. In this study B-cell and CTL epitopes on the E2 3D-structure model were also identified. Thus, the current study provides novel and significant insights into variation in virulence, pathogenesis and antigenicity experienced by CSFV strains after the positive selection pressure effect.

Ämnesord

LANTBRUKSVETENSKAPER  -- Veterinärmedicin -- Annan veterinärmedicin (hsv//swe)

AGRICULTURAL SCIENCES  -- Veterinary Science -- Other Veterinary Science (hsv//eng)

Nyckelord

classical swine fever virus

positive selection pressure

pathogenesis

virulence

antigenicity

surveillance

epidemiologi

Epidemiology

Infectious Diseases

infektionssjukdomar

molekylärbiologi

Molecular Biology

Surface Biotechnology

ytbioteknik

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