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Pigs with 8 wPeks of age were vaccinated with live vaccine of LPC-China strain intramuscularly (IM) or intranasally (IN). All pigs vaccinated IN were sick and dead, and all pigs vaccinaged IM survived when they were challenged with a virulent strain 10 days after vaccination. Results implied that LPC-China strain could not replicate so well at lower temperature condition.
rimary and established cell lines originated from pig kidney and testicle were used for serial passage of LPC-China strain virus. Results showed that a titer of 106.5 TCID50 /ml and 107-5 Rm50/ml could be reached when the tirus was prop-agated in PK-CL cell line. The virus, however, replicated poorly in primary swine kidney, testicle cell cultures and in ESK, ST-CL established cell lines. The virus replicated better at 37°C.
Doses of 1/100, 1 / 1,000 and I/ 5,000 of the virus which has been serial passaged 6 times in PK-CL cell line, was inoculated IM in 8-week old pigs with low neutralizing antbody. All vaccinated pigs survived with a febrile reaction (over 41 °c) when they were chaJlenged 1 0 days after vaccination; on the other hand, all unvaccinated control pigs were killed afgter challenge.
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