Mutation of FMDV Lpro H138 residue drives viral attenuation in cell culture and in vivo in swine

A review of foot-and-mouth disease in Ethiopia: epidemiological aspects, economic implications, and control strategies

Foot-and-mouth disease (FMD) is a contagious viral disease that affects the livelihoods and productivity of livestock farmers in endemic regions. It can infect various domestic and wild animals with cloven hooves and is caused by a virus belonging to the genus Aphthovirus and family Picornaviridae, which has seven different serotypes: A, O, C, SAT1, SAT2, SAT3, and Asia-1. This paper aims to provide a comprehensive overview of the molecular epidemiology, economic impact, diagnosis, and control measures of FMD in Ethiopia in comparison with the global situation. The genetic and antigenic diversity of FMD viruses requires a thorough understanding for developing and applying effective control strategies in endemic areas. FMD has direct and indirect economic consequences on animal production. In Ethiopia, FMD outbreaks have led to millions of USD losses due to the restriction or rejection of livestock products in the international market. Therefore, in endemic areas, disease control depends on vaccinations to prevent animals from developing clinical disease. However, in Ethiopia, due to the presence of diverse antigenic serotypes of FMD viruses, regular and extensive molecular investigation of new field isolates is necessary to perform vaccine-matching studies to evaluate the protective potential of the vaccine strain in the country.

[The role of the encephalomyocarditis virus type 1 proteins L and 2A in the inhibition of the synthesis of cellular proteins and the accumulation of viral proteins during infection]

INTRODUCTION

Infection of cells with encephalomyocarditis virus type 1 (EMCV-1, Cardiovirus A: Picornaviridae) is accompanied by suppression of cellular protein synthesis. The main role in the inhibition of cellular translation is assigned to the L and 2A «security» proteins. The mechanism of the possible influence of the L protein on cellular translation is unknown. There are hypotheses about the mechanism of influence of 2A protein on the efficiency of cap-dependent translation, which are based on interaction with translation factors and ribosome subunits. However, the available experimental data are contradictory, obtained using different approaches, and do not form a unified model of the interaction between the L and 2A proteins and the cellular translation machinery.

AIM

To study the role of L and 2A «security» proteins in the suppression of translation of cellular proteins and the efficiency of translation and processing of viral proteins in infected cells.

MATERIALS AND METHODS

Mutant variants of EMCV-1 were obtained to study the properties of L and 2A viral proteins: Zfmut, which has a defective L; Δ2A encoding a partially deleted 2A; Zfmut&Δ2A containing mutations in both proteins. Translational processes in infected cells were studied by Western-blot and the pulse method of incorporating radioactively labeled amino acids (14C) into newly synthesized proteins, followed by radioautography.

RESULTS

The functional inactivation of the 2A protein does not affect the inhibition of cellular protein synthesis. A direct correlation was found between the presence of active L protein and specific inactivation of cellular protein synthesis at an early stage of viral infection. Nonspecific suppression of the translational processes of the infected cell, accompanied by phosphorylation of eIF2α, occurs at the late stage of infection. Partial removal of the 2A protein from the EMCV-1 genome does not affect the development of this process, while inactivation of the L protein accelerates the onset of complete inhibition of protein synthesis. Partial deletion of the 2A disrupts the processing of viral capsid proteins. Suppression of L protein functions leads to a decrease in the efficiency of viral translation.

CONCLUSION

A study of the role of EMCV-1 L and 2A proteins during the translational processes of an infected cell, first performed using infectious viral pathogens lacking active L and 2A proteins in one experiment, showed that 2A protein is not implicated in the inhibition of cellular translation in HeLa cells; L protein seems to play an important role not only in the specific inhibition of cellular translation but also in maintaining the efficient synthesis of viral proteins; 2A protein is involved not only in primary but also in secondary processing of EMCV-1 capsid proteins.

Reprogramming viral immune evasion for a rational design of next-generation vaccines for RNA viruses

Type I interferons (IFNs-α/β) are antiviral cytokines that constitute the innate immunity of hosts to fight against viral infections. Recent studies, however, have revealed the pleiotropic functions of IFNs, in addition to their antiviral activities, for the priming of activation and maturation of adaptive immunity. In turn, many viruses have developed various strategies to counteract the IFN response and to evade the host immune system for their benefits. The inefficient innate immunity and delayed adaptive response fail to clear of invading viruses and negatively affect the efficacy of vaccines. A better understanding of evasion strategies will provide opportunities to revert the viral IFN antagonism. Furthermore, IFN antagonism-deficient viruses can be generated by reverse genetics technology. Such viruses can potentially serve as next-generation vaccines that can induce effective and broad-spectrum responses for both innate and adaptive immunities for various pathogens. This review describes the recent advances in developing IFN antagonism-deficient viruses, their immune evasion and attenuated phenotypes in natural host animal species, and future potential as veterinary vaccines.