Emergency Foot-and-Mouth Disease Vaccines A Malaysia 97 and A22 Iraq 64 Offer Good Protection against Heterologous Challenge with A Variant Serotype A ASIA/G-IX/SEA-97 Lineage Virus

Abstract

The continuous emergence of foot-and-mouth disease virus (FMDV) serotype A variants in South East Asia is of concern for international FMDV antigen banks, especially when in vitro tests predict a low antigenic match. A vaccination-challenge study was performed by using two emergency FMDV vaccines with A 22 Iraq 64 (A22 IRQ) and A Malaysia 97 (A MAY 97) strains, against challenge with a variant strain of FMDV A/Asia/G-IX/SEA-97 lineage at 7-and 21-day post-vaccination (dpv). At 7 dpv, three of five female calves vaccinated with A MAY 97 and four of five vaccinated with A22 IRQ did not show lesions on the feet and were considered protected, while at 21 dpv all five calves were protected with each vaccine, indicating equal efficacy of both vaccine strains. Calves were protected despite relatively low heterologous neutralizing antibody titers to the challenge virus at the time of challenge. All the calves developed antibodies to the non-structural proteins, most likely due to the direct intradermolingual (IDL) inoculation. Only one calf from the A MAY 97-7 group had infectious virus in the serum 1-3-day post-challenge (dpc), while no virus could be isolated from the serum of cattle challenged on 21 dpv. The virus could be isolated from the oral swabs of all calves, 1-7 dpc with viral RNA detected 1-10 dpc. Nasal swabs were positive for virus 1-6 dpc in a small number of calves. The time between vaccination and infection did not have an impact on the number of animals with persistent infection, with almost all the animals showing viral RNA in their oro-pharyngeal fluid (probang) samples up to 35 dpc. Despite the poor in vitro matching data and field reports of vaccine failures, this study suggests that these vaccine strains should be effective against this new A/Asia/G/SEA-97 variant, provided they are formulated with a high antigen dose.

Chimeric RHDV Virus-Like Particles Displaying Foot-and-Mouth Disease Virus Epitopes Elicit Neutralizing Antibodies and Confer Partial Protection in Pigs

“…Notably, the FMDV VNT titers elicited by VLP L-B/N-T in mice and pigs, were considerably higher than those previously reported for immunization with dendrimeric peptides affording full protection against FMDV challenge [ 33 , 34 , 35 , 37 ], as well as those elicited by current chemically inactivated whole-virus vaccines in pigs and cattle [ 55 , 56 ].…”

A Vaccine Strain of the A/ASIA/Sea-97 Lineage of Foot-and-Mouth Disease Virus with a Single Amino Acid Substitution in the P1 Region That Is Adapted to Suspension Culture Provides High Immunogenicity

“…Cross protection has been recently reported in cattle vaccinated with an emergency vaccine against serotype A FMDV [ 47 ]. Cattle vaccinated with an A/MAY/97 vaccine poorly matching with an A/ASIA/Sea-97 lineage virus were protected against the A/ASIA/Sea-97 lineage virus.…”

Emergency FMD Serotype O Vaccines Protect Cattle against Heterologous Challenge with a Variant Foot-and-Mouth Disease Virus from the O/ME-SA/Ind2001 Lineage

“…The oral fluid was collected on 0, 1-7, 11, 14, 18, 21, 25, 28 and 32 dpc with Salivette swabs, extracted using 0.5 mL of minimal essential medium supplemented with 5% fetal bovine serum and 10% antibiotic cocktail and transferred to fresh tubes. Nasal swabs were collected on the same days as the oral swabs using sterile cotton swabs and placed in 2 mL of minimal essential medium supplemented with 5% fetal bovine serum and 10% antibiotic cocktail [16][17][18][19][20]. Oro-pharyngeal fluids were collected using probang cups on 0, 11, 14, 18, 21, 25, 28 and 32 dpc and diluted 1:1 in Earle's MEM (2% fetal bovine serum and 2% antibiotic cocktail [21].…”