Infection expérimentale de porcs exempts d'organismes pathogènes spécifiques avec une souche du virus de la grippe porcine (HSW₁N₁) et étude de la durée d'excrétion virale

摘要

A swine influenza virus (HSW1N1) isolated from an outbreak with respiratory disorders was experimentally inoculated to two groups of specific pathogen free pigs to study the pathogenicity of this strain and the period of shedding of the virus by the infected pigs. After the infection of the 12 oldest pigs (130 days old) no clinical sign was observed. Pneumonia was observed in three pigs of the 12 infected pigs slaughtered early after inoculation. The lung lesions were moderate and small. After the infection of the 22 seven week old pigs, hyperthermia appeared in 14 pigs and lasted approximately 48 hours. Lesions of pneumonia were seen on the lung of only one pig slaughtered eight days after the infection. The virus had been recovered from nasal swabs, on one pig, 29 days after the experimental infection, but all the contact trials with noninfected specific pathogen free pigs, 30-45 and 60 days after the experimental infection, failed. So, after experimental inoculation, the swine influenza virus weakly multiplied in pigs and its pathogenicity was moderate. In our experimental conditions, the shedding period of the virus was relatively short, less than four weeks. The possible reasons for the clinical reaction variation to the natural or experimental infection are discussed.