Factors affecting the infectivity of tissues from pigs with classical swine fever: Thermal inactivation rates and oral infectious dose

Abstract

Outbreaks of classical swine fever are often associated with ingestion of pig meat or products derived from infected pigs. Assessment of the disease risks associated with material of porcine origin requires knowledge on the likely amount of virus in the original material, how long the virus may remain viable within the resulting product and how much of that product would need to be ingested to result in infection. Using material from pigs infected with CSFV, we determined the viable virus concentrations in tissues that comprise the majority of pork products. Decimal reduction values (D values), the time required to reduce the viable virus load by 90% (or 1 log10), were determined at temperatures of relevance for chilling, cooking, composting and ambient storage. The rate of CSFV inactivation varied in different tissues. At lower temperatures, virus remained viable for substantially longer in muscle and serum compared to lymphoid and fat tissues. To enable estimation of the temperature dependence of inactivation, the temperature change required to change the D values by 90% (Z values) were determined as 13 °C, 14 °C, 12 °C and 10 °C for lymph node, fat, muscle and serum, respectively. The amount of virus required to infect 50% of pigs by ingestion was determined by feeding groups of animals with moderately and highly virulent CSFV. Interestingly, the virulent virus did not initiate infection at a lower dose than the moderately virulent strain. Although higher than for intranasal inoculation, the amount of virus required for infection via ingestion is present in only a few grams of tissue from infected animals.

Analysis of antibiotics resistant genes in different strains of Staphylococcus aureus

“…S. aureus is a part of the most clinically important pathogens causing severe economic losses worldwide [ 24 ]. The fast evolution of S. aureus resistant strains has rendered most current antibiotics ineffective, hence raised a global concern [ 24 ].…”

“…S. aureus is a part of the most clinically important pathogens causing severe economic losses worldwide [ 24 ]. The fast evolution of S. aureus resistant strains has rendered most current antibiotics ineffective, hence raised a global concern [ 24 ]. There is an urgent need for rapid detection of unique ARGs, which could aid in improvements in global surveillance [ 25 , 26 ].…”

Inactivation of Classical Swine Fever Virus in Porcine Serum Samples Intended for Antibody Detection

“…The significance of the CSFV inactivation is underlined by the fact that this topic had been already targeted before. However, former studies exclusively addressed virus inactivation in tissues or other matrices that are not relevant for serological analysis upon shipping [5,12,13]. The focus of the present study was to define a pragmatic procedure for inactivation of CSFV in serum without impairing the serological properties for subsequent antibody detection by ELISA and cell culture-based VNTs.…”

“…In this context, it has been reported that, even though CSFV can be considered as a moderately fragile virus, prolonged survival is possible under favorable conditions such as a protein-rich milieu [13]. Different results have been published with regard to the influence of the properties of the viral strain on virus stability [5,12,14]. In the present study, no differences regarding virus inactivation were detected between the highly virulent strains CSF0947 and CSF0634 and the two moderately virulent strains CSF0902 and CSF0104.…”

“…Usually, complement inactivation (incubation at 56 • C for 30 min) of serum samples is performed prior to diagnostic analysis. However, this treatment results in a reduced viral titer of only about one log 10 and is consequently insufficient to inactivate CSFV in serum samples because of virus protecting abilities of porcine serum at 56 • C and ambient temperatures [5]. For virus inactivation by heating, higher temperatures would be required.…”