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發表於 2011-12-28 00:20:34
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本帖最後由 蘇少儀 於 2011-12-28 09:49 編輯
Live attenuated vaccines were demonstrated to be very efficient at preventing disease.
The first immunisation experiments with live attenuated lapinised strains (attenuated after serial passages in rabbits) were performed over 60 years ago (Koprowski et al., 1946). Since then, little progress has been made in this field. CSFV attenuated vaccines are safe, induce high levels of neutralising antibodies and are capable of protecting against highly virulent strains of CSFV, even in pregnant sows as early as 5 days after vaccination.
雖然，各個兔化豬瘟減毒疫苗株（經由兔子連續繼代進行減毒）首度進行免疫試驗距今已60多年了，但是，豬瘟減毒疫苗經驗證對疾病預防上具有非常好的效果，而且即便田間使用兔化豬瘟疫苗，從那個年代起迄今其間的進展有限，然而豬瘟減毒疫毒仍是安全，誘發高度中和抗體而且能夠保護疫苗接種豬隻；即便是懷孕母豬在接種疫苗後的五天後即能夠產生對抗各個高毒力豬瘟病毒株的保護效果．
Attenuated CSFV vaccines remain the method of choice to control the disease, especially in areas in which CSF remains enzootic.
The mechanisms mediating the protection conferred by attenuated strains of CSFV are not fully understood. Vaccinated animals are protected against disease before neutralizing antibodies are detected (Suradhat et al., 2001).
After vaccination with the C strain, antibodies are detectable as early as 12 days post-immunisation, reaching a peak at 4–12 weeks (Precausta et al., 1983; Terpstra et al., 1990). Antibodies can persist for life in animals that have received a single dose of vaccine (Terpstra and Tielen, 1976).
接種減毒豬瘟疫苗仍為控制豬瘟的方法之一，尤其是仍然發生豬瘟病例的區域．接種減毒豬瘟疫苗後，豬隻在中和抗體被檢出之前即具有保護效果，雖然此一保護效果的機制仍待釐清．接種豬瘟C株疫苗（註：類似臺灣使用的LPC株）後，最早可在接種後12天測得抗體，抗體力價在第4至12週時達到高峰．曾有文獻指出，豬隻在免疫適期接種一劑兔化豬瘟減毒疫苗，抗體可持續終身．
Two vaccines licensed by the European Agency for the Evaluation of Medicinal Products (EMEA) are commercially available (Bayovac CSF, Bayer; Porcilis Pestis, Intervet). Vaccinated animals develop specific antibodies that exclusively recognize the E2 glycoprotein, whereas pigs infected with field strains of CSFV also develop antibodies against the Erns protein, which can be distinguished with a specific enzyme-linked immunosorbent assay (ELISA) (de Smit et al., 2001). Despite the advantages of using subunit vaccines, their protective efficacy is still under evaluation (Paton and Greiser-Wilke, 2003; Greiser-Wilke and Moennig, 2004).
Bayovac CSF, Bayer及Porcilis Pestis, Intervet等二種經歐盟醫療產品評估機構（EMEA）核准上市的疫苗，使用此二種疫苗接種豬隻後產生的抗體只與豬瘟病毒結構上特定的E2醣蛋白（E2 glycoprotein）結合，而豬隻感染野外病毒株後，除對E2醣蛋白產生抗體外，亦對Erns蛋白質產生抗體，因此可應用此一差異，使用檢測Erns蛋白質的酵素連結免疫吸附法（ELISA）作為區別疫苗接種或野外病毒感染之用．估不論次單位疫苗的優點，其保護效力仍在評估之中．
Compared with classical attenuated vaccines, the protection conferred with subunit vaccines is much more limited, especially among pregnant sows, and there is a higher risk of establishment of persistently infected individuals (Ahrens et al., 2000; Depner et al., 2001; de Smit et al., 2001; Paton and Greiser-Wilke, 2003; van Oirschot, 2003b; Greiser-Wilke and Moennig, 2004; Vannier, 2004).
相較於傳統的減毒疫苗，接種次單位疫苗所產生的保護效果相當有限；尤其是懷孕母豬，而且發生豬隻持續性感染方面具有比較高的風險．
Two final reasons, both related to the lack of efficient differential diagnostic methods, have contributed to the non-implementation of these vaccine strategies as an emergency measure in the field (Vannier, 2004). Firstly, specific antibodies against Erns are not developed until 3–6 weeks after natural infection with field strains of CSFV (depending on the virulence of the CSFV strain), which makes the differential diagnosis at early stages of infection difficult (de Smit et al., 2000). Secondly, the available Erns based ELISAs are still far from being as sensitive and specific as the E2 based ELISAs (Greiser-Wilke and Moennig, 2004).
最後二個與現今仍缺乏有效區別診斷方法有關，而無法使用次單位疫苗作為田間緊急接種的疫苗接種策略的理由．其一是豬隻自然感染野外病瘟病毒株時，需要3到6週（依豬瘟病毒的毒力而定）才可測得抗Erns蛋白的抗體，這造成感染早期階段，區別診斷上的困難．其次為現有檢測Erns抗體的酵素連結免疫吸附法（ELISA）試劑的敏感性及特異性距離實用階段仍有很大的改良空間．
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