For example, following the introduction of ASF to Spain and Libraries Portugal in 1960, field isolate viruses were serially passed through primary bone marrow or blood macrophage cell cultures and then used to vaccinate pigs in Spain and Portugal. A substantial proportion of the half million pigs vaccinated in Portugal developed unacceptable post-vaccination reactions, including death [13]. In addition, a large number of carrier animals were generated, hindering subsequent attempts to eradicate the disease [14]. In the absence of a vaccine, control measures are currently limited to slaughter and the application of strict animal movement restriction policies. Despite this early

experience in Portugal and Spain, see more the prospect of developing successful attenuated vaccines have improved as substantial progress has been made in identifying ASFV genes involved in virulence and immune evasion and the complete coding sequences of a number of ASFV isolates are now available [15], [16] and [17]. This information provides a route to the rational construction of attenuated ASFV vaccines. Currently knowledge of the antigens involved in protective immunity and the ability of isolates to confer cross-protection is limited. In this study we extended our previous work with an

experimental ASFV vaccination strategy based on the non-virulent genotype I OURT88/3 isolate from Portugal. We confirmed that immunisation with this isolate followed by the virulent OURT88/1 isolate confers protection against challenge with two virulent isolates from Africa, selleckchem one, Benin 97/1, from the same genotype I and the other, virulent Uganda 1965, from genotype X. We also show that the ability of different ASFV isolates to stimulate IFN-γ production from the immune pig lymphocytes correlates with the ability to induce cross-protection against different isolates. Thus this assay is useful to predict cross-protection and vaccine efficacy. These results suggest that ASFV vaccines which

cross-protect more broadly could be produced, extending the possible use of a vaccination strategy. ASFV isolates used in this study have been described previously and included Portuguese isolates of ASFV, OURT88/3 (non-virulent, non-haemadsorbing, genotype I) and OURT88/1 oxyclozanide (virulent, haemadsorbing, genotype I) [2], virulent Portuguese pig isolate Lisbon 57 (genotype I; [18]), moderately virulent Malta isolate Malta/78 (genotype I; [19]), virulent West African isolate Benin 97/1 (genotype I; [15]) virulent African isolates Uganda 1965 (genotype X; [20]) and Malawi Lil 20/1 (genotype VIII; [21]). Viruses were grown in primary porcine macrophage cultures and used after limited passage. Pigs used in the first experiment (experiment 1) at IAH Pirbright Laboratory UK were cross-bred pigs, Large White and Landrace, of average weight 20 kg at the first immunisation.