Emergency vaccination of cattle against lumpy skin disease: Evaluation of safety, efficacy, and potency of MEVAC® LSD vaccine containing Neethling strain.

Lumpy skin disease (LSD) is an emerging disease of cattle causing significantly high economic losses. Control of LSD depends on the use of homologous attenuated LSD virus strains isolated originally from South Africa (the Neethling strain). The virus belongs to the genus Capripoxvirus, which includes sheep pox virus and goat pox virus. The present study was conducted to evaluate the safety and efficacy of a new live attenuated LSD vaccine produced by Middle East for Vaccines (MEVAC®) based on the Neethling strain. Tests were performed both in Egypt and Vietnam. Safety was evaluated by inoculation of five cattle with 10 times the recommended dose and observation of the animals for 14 days. Immunogenicity was tested at different periods post-vaccination (PV) in animals receiving the recommended doses of the vaccine using ELISA and virus neutralization test. Five cows were used to determine the protection index (PI) and non-vaccinated control cattle were included. Three calves were challenged by intradermal inoculation of the wild virus (5 × 105 TCID50) 28 days PV. Field or mass vaccination experiments were conducted in Vietnam during national campaigns in the summer of 2021 with 4301 vaccinated animals closely monitored after vaccination. In the field, around 2% (80/4301) of the animals showed hyper-reactivity, and 0.6% (24/4301) showed small skin swellings that disappeared within few hours PV. Abortion was recorded in three animals (0.3% 3/867). Challenged animals were resistant to clinical disease and PI value was 3.5 log10. Meanwhile, antibody levels determined by the ELISA were inconsistent among animals and laboratories during the study period. Overall, the findings point to a new safe and effective LSD vaccine.

Studies on infectious myonecrosis virus (IMNV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) in cultured penaeid shrimp in Egypt.

The present study aimed to diagnose infectious myonecrosis virus (IMNV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) among cultured penaeid shrimp (Penaeus semisulcatus, n = 120) collected from private farms in 2 Egyptian provinces (Damietta and North Sinai) along the Mediterranean coast. The collected shrimp were subjected to clinical examination, histopathology, molecular characterization, and phylogenetic analysis. Most of the shrimp infected with IMNV showed a distinctive appearance resembling cooked shrimp and white necrosis on distal abdominal segments and tail fans. Simultaneously, IHHNV-infected cases displayed opaque abdominal muscles, white milky to buff mottling on the shell, and a pathognomonic runt-deformity syndrome. Histopathological examination of infected specimens revealed muscular edema, hemocyte infiltration, deformities, Zenker's necrosis, and eosinophilic intra-nuclear inclusion bodies (Cowdry type A). PCR results gave predictable amplicon sizes of 139 and 81 bp and confirmed the presence of IMNV and IHHNV with a total prevalence of 37.5 and 25%, respectively. A homology search by BLAST analysis showed that the retrieved isolates putatively belonged to IMNV and IHHNV based on 96.3 to 97% nucleotide identity to the corresponding open reading frame gene of each virus. The phylogenetic analysis clearly showed genetic similarity and cross-lineage between our isolates and other isolates from Egypt, the USA, Brazil, Indonesia, China, Korea, Taiwan, and Ecuador. In conclusion, gross inspection and histopathology may aid in the diagnosis of viral diseases; however, molecular tools are indispensable for confirming a possible infection. The current study recommends strict regulations during live shrimp transportation and implementing health control certificates over all imports and exports, especially in developing countries, including Egypt.