Abstract
BackgroundTo assess the effectiveness of emergency vaccination for reducing the contact-induced infection and pathological damage caused by the highly pathogenic porcine reproductive and respiratory syndrome virus (HPPRRSV), Twenty pigs were equally divided into four groups. Groups 1, 2 and 3 were housed in one unit, whereas Group 4 was separately housed. Group 1 was challenged with HPPRRSV on day 0. Group 2 and 4 did not receive treatment and were used as the contact-infected and uninfected controls, respectively. Group 3 was treated with the attenuated vaccine at 0 days post-inoculation. The rectal temperatures, clinical signs, pathologic lesions and viraemia of the piglets were detected and evaluated.ResultsThe vaccinated pigs in Group 3 showed less clinical morbidity, viraemia, temperature fluctuations and lung lesions at 14 days post-inoculation, as compared with the contact-infected (Group 2) and experimentally infected (Group 1) pigs. Higher serum IFN-γ levels were detected among the pigs that received emergency immunisation. Thus, IFN-γ may be involved in immunity against HPPRRSV infection.ConclusionsThese results indicated that emergency vaccination could effectively alleviate HPPRRSV infection during experimental contact exposure. Our findings provide a novel and useful strategy for controlling clinical HPPRRSV.
Highlights
To assess the effectiveness of emergency vaccination for reducing the contact-induced infection and pathological damage caused by the highly pathogenic porcine reproductive and respiratory syndrome virus (HPPRRSV), Twenty pigs were divided into four groups
This study aimed to replicate clinical cases under experimental conditions to confirm the effects of emergency immunisation, which may be widely used for emergency cases of HPPRRSV infection
Aside from the high fever, the appearance of typical HPPRRSV-induced characteristics was delayed for almost eight days in Group 3
Summary
To assess the effectiveness of emergency vaccination for reducing the contact-induced infection and pathological damage caused by the highly pathogenic porcine reproductive and respiratory syndrome virus (HPPRRSV), Twenty pigs were divided into four groups. Group 3 was treated with the attenuated vaccine at 0 days post-inoculation. The highly pathogenic porcine reproductive and respiratory syndrome virus (HPPRRSV) in China was first reported in 2006; the outbreak overwhelmed ten provinces (including autonomous cities or regions) with more than 2,000,000 infected pig within the first four months [1]. An HPPRRSV-derived attenuated vaccine was developed to control the disease [3]. The attenuated vaccine of a modified-live virus (MLV) derived from the American PRRSV VR-2332 has been widely used in PRRSV-prevalent countries, with its safety and effectiveness proven by previous studies [4,5].
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