Sequence Analysis of Egyptian Foot-and-Mouth Disease Virus Field and Vaccine Strains: Intertypic Recombination and Evidence for Accidental Release of Virulent Virus

Abstract

In spite of annual mass vaccination programs with polyvalent inactivated vaccines, the incidence and economic impact of foot-and-mouth disease (FMD) in Egypt is high. Viruses of the A, O and SAT 2 serotypes are endemic and repeated incursions of new lineages from other countries lead to an unstable situation that makes the selection of appropriate vaccine antigens very difficult. In this study, whole genome sequencing of a 2016 serotype A isolate from Egypt revealed a recombination event with an African serotype O virus. Based on available vaccine matching data, none of the vaccines currently used in Egypt are expected to sufficiently protect against this virus or other viruses of this lineage (A/AFRICA/G-IV) circulating there since 2012. In addition to the risk of vaccine failure caused by strain mismatch, the production of inactivated FMD vaccines is dangerous if adequate biosafety cannot be maintained. Using a high-throughput sequencing protocol optimized for short nucleic acid fragments, the composition of a local inactivated vaccine was analyzed in depth. The serotype O strain identified in the vaccine was genetically identical to viruses found in recent FMD outbreaks in Egypt.

Comments on Sequence Analysis of Egyptian Foot-and-Mouth Disease Virus Field and Vaccine Strains: Intertypic Recombination and Evidence for Accidental Release.

“…Strain (O/EGY/10/2011) is commonly included in the current local vaccines. Sobhi et al [9] observed two different strains of serotype O, one related to PanAsia-2 in Upper Egypt and the Delta (i.e., most of Egypt) and the other, was probably less immunodominant and related to the East African strains in Sharkia province This is not in line with the conclusions of Abdel Rahman et al [1], who reported that the vaccinal strain of serotype O has shown variable sequence alignment and phylogenecity profiles, being generally comparable to other O/ME-SA strains, while the leader protein-coding zone (five prime untranslated region) was more or less similar to those of some historical EURO-SA vaccine strains, including O1/Campos/BRA/58 and O1/BFS1860/UKG/67. The authors also report that the virus in the inactivated vaccine (of lineage O/ME-SA, box A) was very distant from the lineage O/EA-3 strains (box B).…”

“…The article by Abdel Rahman et al [1] reported that 62 clinical samples (blood, serum, white blood cells and swabs from the nose, mouth and saliva) were collected from two cattle and 2 buffaloes in 2016. Only saliva samples from the 4 animals were positive for FMDV serotype A by PCR, but the virus was detected in cell cultures from 3 samples.…”

“…Further, the authors did not provide the vaccination history of the animals, although this may have been the case, with no sloughed tongue epithelium and negative PCR results from the blood and serum (Stenfeld et al) [5]. The speculation that current vaccines in Egypt are not expected to necessarily protect from lineage A/AFRICA/G-IV is controversial, since cross protection by A-Iran 05 has been demonstrated before [6] and the authors themselves [1] have paradoxically reported that highly efficacious vaccines against FMDV serotype A could produce protection against heterologous strains, regardless of low matching results in vitro. However, the epidemiological situations during the 3 years interval between the field and vaccine analyses may not necessarily be the same, which explains the absence of A/AFRICA from the current local vaccines [3].…”

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Egyptian Journal of Veterinary Sciences https://ejvs.journals.ekb.eg/ 27 M OLECULAR epidemiology research on foot-and-mouth disease (FMD) viruses typically requires information on the study population and a sufficient number of samples for accurate detection and trending of serotypes and lineages in a region or country. Based on the study of Abdel Rahman et al [1], this commentary is to draw the attention to insufficient sample size and limited geographical locations that represent the circulating field strains of foot-and-mouth disease (FMD) virus in Egypt during 2016. Sequence analysis of one FMD vaccine sample produced locally in 2019 was compared to circulating strains in 2016, irrespective of time difference.

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Field Observations and Genetic Characterization of Sheep-Associated Malignant Catarrhal Fever in Egypt, 2018

“…Nucleic acids were extracted from 100 µL of each sample with the NucleoMag VET kit (Macherey-Nagel, Düren, Germany) on a KingFisher Flex Magnetic Particle Processor (Thermo Fisher Scientific, Waltham, MA, USA) following the manufacturers’ instructions. The extracted nucleic acids were tested for AlHV-1 [ 19 ] and OvHV-2 [ 20 ] DNA by real-time PCR using the PerfeCTa qPCR ToughMix (Quantabio, Beverly, MA, USA) in a CFX96 thermocycler (Bio-Rad, Hercules, CA, USA) as well as for FMD virus [ 21 ], BVDV [ 22 ], and BoHV-1 [ 23 ] as previously described. A lymphoid tissue preparation from an Italian case of sheep-associated bovine MCF from 2007 (record no.…”