ICAR-Indian Veterinary Research Institute, Hebbal, Bengaluru, 560024, India.
ICAR- Directorate of Foot and Mouth Disease, Mukteswar, Nainital, 263138, India.
Appl Microbiol Biotechnol. 2020 Mar;104(6):2589-2602. doi: 10.1007/s00253-020-10370-z. Epub 2020 Jan 30.
Foot-and-mouth disease (FMD) is a highly contagious, economically significant disease of cloven-hoofed animals caused by FMD virus (FMDV) of the Picornaviridae family. Vaccination of susceptible animals with inactivated virus vaccine is the standard practice for disease control. The prophylactic use of the inactivated vaccines has reduced the disease burden in many countries endemic to FMD. In the process of implementation of the mass vaccination program and disease eradication, it is essential to differentiate infected from vaccinated animals (DIVA) where a large proportion of the animal population is vaccinated, and disease-free zones are being established, to help in sero-surveillance of the disease. In such a scenario, the use of a negative marker vaccine is beneficial to rule out false-positive results in a disease-free zone. Here we report the construction and rescue of an infectious cDNA clone for FMDV serotype A Indian vaccine strain lacking 58 amino acid residues (87-144 amino acid position) in the carboxy-terminal region of the viral 3A protein. The recombinant deletion mutant virus showed similarity in the antigenic relationship with the parental strain. Immunization of guinea pigs with the inactivated vaccine formulated using the deletion mutant virus induced potent immune response with 100% protective efficacy upon challenge with homologous virus. Further, we show that sera from the guinea pigs infected with the deletion mutant virus did not show reactivity in an indirect ELISA test targeting the deleted portion of 3A protein. We conclude that the recombinant deletion mutant virus vaccine along with the newly developed companion indirect ELISA targeting portion of FMDV 3A protein could be useful in the implementation of a precise DIVA policy in our country when we reach FMD free status with vaccination.
口蹄疫（FMD）是一种由小核糖核酸病毒科口蹄疫病毒（FMDV）引起的偶蹄动物高度传染性、经济意义重大的疾病。用灭活病毒疫苗对易感动物进行接种是疾病控制的标准做法。在许多口蹄疫流行的国家，预防性使用灭活疫苗已经减少了疾病负担。在实施大规模疫苗接种计划和疾病根除的过程中，区分接种和未感染动物（DIVA）至关重要，在这种情况下，大量动物群体接种疫苗，并且正在建立无疫区，以帮助进行疾病血清学监测。在这种情况下，使用阴性标记疫苗有助于排除无疫区的假阳性结果。在这里，我们报告了构建和拯救一种缺失 58 个氨基酸残基（87-144 位氨基酸位置）的口蹄疫病毒血清型 A 印度疫苗株的传染性 cDNA 克隆，该缺失发生在病毒 3A 蛋白的羧基末端区域。重组缺失突变病毒在抗原关系上与亲本株相似。用缺失突变病毒制备的灭活疫苗免疫豚鼠，可诱导产生强烈的免疫反应，同源病毒攻毒时保护效力为 100%。此外，我们还表明，感染缺失突变病毒的豚鼠血清在针对 3A 蛋白缺失部分的间接 ELISA 试验中没有反应性。我们得出结论，重组缺失突变病毒疫苗以及新开发的针对 FMDV 3A 蛋白部分的伴随间接 ELISA 可以在我们国家达到 FMD 无疫区状态并通过接种疫苗实现精确 DIVA 政策时发挥作用。
