Kinetics of hepatitis C (HCV) viraemia and quasispecies during treatment of HCV associated cryoglobulinaemia with pulse cyclophosphamide

Virus Adaptation and Selection Following Challenge of Animals Vaccinated against Classical Swine Fever Virus

Vaccines against classical swine fever have proven very effective in protecting pigs from this deadly disease. However, little is known about how vaccination impacts the selective pressures acting on the classical swine fever virus (CSFV). Here we use high-throughput sequencing of viral genomes to investigate evolutionary changes in virus populations following the challenge of naïve and vaccinated pigs with the highly virulent CSFV strain “Koslov”. The challenge inoculum contained an ensemble of closely related viral sequences, with three major haplotypes being present, termed A, B, and C. After the challenge, the viral haplotype A was preferentially located within the tonsils of naïve animals but was highly prevalent in the sera of all vaccinated animals. We find that the viral population structure in naïve pigs after infection is very similar to that in the original inoculum. In contrast, the viral population in vaccinated pigs, which only underwent transient low-level viremia, displayed several distinct changes including the emergence of 16 unique non-synonymous single nucleotide polymorphisms (SNPs) that were not detectable in the challenge inoculum. Further analysis showed a significant loss of heterogeneity and an increasing positive selection acting on the virus populations in the vaccinated pigs. We conclude that vaccination imposes a strong selective pressure on viruses that subsequently replicate within the vaccinated animal.

Sequencing approach to analyze the role of quasispecies for classical swine fever

Classical swine fever virus (CSFV) is a positive-sense RNA virus with a high degree of genetic variability among isolates. High diversity is also found in virulence, with strains covering the complete spectrum from avirulent to highly virulent. The underlying genetic determinants are far from being understood. Since RNA polymerases of RNA viruses lack any proof-reading activity, different genome variations called haplotypes, occur during replication. A set of haplotypes is referred to as a viral quasispecies. Genetic variability can be a fitness advantage through facilitating of a more effective escape from the host immune response. In order to investigate the correlation of quasispecies composition and virulence in vivo, we analyzed next-generation sequencing data of CSFV isolates of varying virulence. Viral samples from pigs infected with the highly virulent isolates "Koslov" and "Brescia" showed higher quasispecies diversity and more nucleotide variability, compared to samples of pigs infected with low and moderately virulent isolates.

Rheumatic manifestations of hepatitis C infection

Among chronic viral infections, hepatitis C virus (HCV) infection is uniquely associated with an array of rheumatic manifestations and autoimmune laboratory findings. These include, among others, arthralgias, arthritis, fatigue, fibromyalgia, vasculitis, and sialadenitis (Sjögren-like). The mechanisms that are involved in the pathogenesis of these diverse manifestations have not yet been clarified. Regardless of the direct or indirect pathogenetic role of HCV in these clinical entities, the concomitant presence of a chronic viral infection creates a number of diagnostic and therapeutic problems. This is particularly true when immunosuppressive therapy is needed for control of disease activity (eg, HCV-associated cryoglobulinemic vasculitis). The emerging treatment options for chronic HCV offer a major chance for viral eradication and conceivably for cure of these HCV-associated conditions. In this review, the recent advances in the epidemiology, pathogenesis, clinical findings, and treatment of HCV-associated rheumatic conditions are presented.