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 8C, 14 8C,
12 8C and 10 8C 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.