Blackburn N K, Swanepoel R
Department of Virology, University of the Witwatersrand, Republic of South Africa.
Trop Anim Health Prod. 1988 Nov;20(4):203-10. doi: 10.1007/BF02239981.
Tests for neutralising (NT) antibodies to the nine serotypes of African horse sickness (AHS) virus on the sera of three groups of horses confirmed that an increasing number of immunisations with vaccine containing attenuated strains of serotypes 1 to 6 of the virus, leads to broader response to the various serotypes and to higher individual titres. Nevertheless some horses failed to respond to one or more serotypes despite receiving numerous immunisations and it was clear that vaccine containing only serotypes 1 to 6 could not be relied upon to induce adequate cross-immunity to serotypes 7 to 9 of the virus. Highest antibody titres and broadest cross-reactivity were recorded in a fourth group of horses which had apparently suffered natural infection recently. The levels of antibody acquired from colostrum by seven foals generally correlated well with the levels of antibody in the sera of their dams and the rate of decline of passively acquired antibody was proportional to initial titre. Antibodies to individual serotypes of virus declined to undetectable levels in two to four months from birth in some instances implying that susceptibility to infection could occur well before the age of six to nine months which is commonly recommended for initial immunisation. Vaccination of eight foals at three to four months of age resulted in weak antibody response but did not adversely affect pre-existing low levels of maternal antibody so that early immunisation could be recommended as a means for attempting to control the losses of foals experienced in Zimbabwe.
对三组马匹血清中针对非洲马瘟（AHS）病毒九种血清型的中和（NT）抗体进行检测，结果证实，用含有该病毒1至6型减毒株的疫苗进行免疫接种的次数增加，会导致对各种血清型的反应范围更广，个体抗体滴度更高。然而，一些马匹尽管接受了多次免疫接种，但仍对一种或多种血清型没有反应，而且很明显，仅含1至6型血清型的疫苗不能可靠地诱导对该病毒7至9型血清型产生足够的交叉免疫。在第四组最近显然遭受自然感染的马匹中，记录到了最高的抗体滴度和最广泛的交叉反应性。七匹幼驹从初乳中获得的抗体水平通常与其母马血清中的抗体水平密切相关，被动获得的抗体的下降速率与初始滴度成正比。在某些情况下，针对病毒个别血清型的抗体在出生后两到四个月降至检测不到的水平，这意味着在通常建议首次免疫的六到九个月龄之前很久就可能发生感染易感性。对八匹三到四个月龄的幼驹进行疫苗接种，产生的抗体反应较弱，但并未对已有的低水平母源抗体产生不利影响，因此可以建议早期免疫接种，作为试图控制津巴布韦幼驹损失的一种手段。
