Evolution of porcine reproductive and respiratory syndrome (PRRS) virus during sequential pig passages

Porcine reproductive and respiratory syndrome (PRRS) viruses are recognized as possessing a high degree of genetic and antigenic variability. Virus diversity has led to questions regarding the association of virus mutation and persistent infection in the host and raised concerns vis-a-vis protective immunity, the ability of diagnostic assays to detect novel variants, and the emergence of virulent strains. The purpose of this study was to assess on-going changes in PRRS virus during replication in pigs under experimental conditions.;Animals were inoculated with a plaque-cloned virus derived from VR-2332, the North American PRRS virus prototype, and 3 independent lines of in vivo replication were maintained for 367 days by pig-to-pig passage of virus at 60 day intervals. A total of 315 plaque-cloned viruses were recovered from pigs over the 367 day observation period and compared to the original plaque-cloned virus by sequencing of open reading frames (ORFs) 1b (replicase), 5 (major envelope protein), and 7 (nucleocapsid) of the genome. In addition, a one-way virus neutralization assay was performed to detect escape mutant variants and a panel of monoclonal antibodies, including five monoclonal antibodies against the nucleocapsid protein and two against the envelope protein, were used to screen for viral epitopic changes.;Virus variants were detectable by day 7 post inoculation and multiple variants were present concurrently in every pig sampled over the observation period. Over the course of 367 days of virus evolution, the mean mutation rate in ORFs 1 b, 5, and 7 was estimated at 6.7, 7.0, and 1.3 changes per 1000 nucleotides, or 0.2, 12.4, and 1.1 per 1000 amino acids. Thus, sequence analysis showed ORFs 1 b and 7 to be highly conserved at the amino acid level relative to ORF 5. Among the 315 virus clones, a total of 48 nucleotide and 22 amino acid ORF 5 variants were detected, with most of the mutations occurring as substitutions. Although the virus neutralization assay and monoclonal antibody analysis detected no escape mutant viruses or epitopic changes, PRRS virus was shown to evolve continuously during replication in infected pigs, with different genes of the viral genome facing differing degrees of positive and/or negative selection

The Development of a Computer Auditing System Sufficient for Sarbanes-Oxley Section 404 - A Study on the Purchasing and Expenditure Cycle of the ERP System

After Section 404 of the Sarbanes-Oxley Act was released, developing an effective computer auditing system became critical for management and auditors. In this study, the researchers used Gowin\u27s Vee, raised as a research strategy by Novak and Gorwin (1984). On the theoretical side, the researchers arranged documents and employed an expert questionnaire to identify 8 operational procedure elements and 34 critical factors for the purchasing and expenditure cycle. The application side was built upon the model. The researchers then developed the computer auditing system based on the developments of this study. To test the suitability of the system, the researchers conducted a case study whose results showed that this system can provide the company owners and their accountants with a simple, continuous, timely, and analytical method which may help them detect promptly any irregular internal control issues, thus identifying measures to improve the condition