Reduction of foot-and-mouth disease virus transmission in cattle vaccinated one or two weeks before challenge using a commercial polyvalent vaccine

Sergio Duffy,Norberto Fondevila,Sabrina Galdo Novo,María Aznar,Carlos Garro,Eliana Smitsaart,Gustavo Monti

doi:10.1016/j.jvacx.2020.100063

Abstract

Immediate vaccination of the most susceptible and epidemiological relevant animals is a crucial part of control measures that facilitate virus elimination in case of entry of foot-and-mouth disease (FMD). The objective of this study was to evaluate the effect of cattle vaccination 7 and 14 days prior challenge using a vaccine commonly applied in systematic vaccination campaigns against transmission of FMD virus (FMDV). Transmission of FMDV was investigated in three groups of ten cattle each: one non-vaccinated group and two groups that were either vaccinated 7 days (−7/vaccinated group) or 14 days (−14/vaccinated group) before intranasal (IN) inoculation. Five cattle heads from each group were inoculated using the IN-route with the A/Argentina/2001 FMDV strain, while the remaining five cattle heads of each group were contact-exposed to inoculated cattle. Clinical signs were recorded; virus isolation and genome detection by RT-PCR were carried out on oesophageal–pharyngeal fluid (OPF) and blood. Neutralizing antibody titers and antibodies against non-structural proteins (NSP) of FMDV were also determined. Results suggest that the experimental design, virus challenge dose, and virus infectivity were appropriate and that the virus had been transmitted to naïve calves. Under the outlined experimental conditions, vaccination 7 and 14 days prior to challenge induced full clinical protection against virus inoculation. Moreover, −7/ or −14/vaccinated calves that had been contact-exposed to −7/ or −14/vaccinated IN-challenged calves, did not become infected. Consequently, no virus transmission occurred from vaccinated and subsequently infected calves to cohabitating vaccinated calves (R = 0). According to our results, early vaccination during an outbreak is effective as virus transmission can be significantly reduced using a vaccine commercially available, routinely applied in systematic vaccination campaigns.

Highlights

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals and considered the socioeconomic most important disease of livestock
The objective of this study was to evaluate the effect of cattle vaccination 7 and 14 days prior challenge using a commercial vaccine on the transmission of FMD virus (FMDV)
In agreement with the results presented in this controlled study, field evidence on the effects of vaccination reducing within herd transmission was reported by Brito et al [30] in which the protective effect of the vaccine was evidenced by the association between vaccination and low rate of within herd transmission

Summary

Introduction

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals and considered the socioeconomic most important disease of livestock. Introduction of FMDV into several FMD-free countries where vaccination is not practised caused severe epidemics FMD-free countries where vaccination is practised, such as Argentina (2006), Brazil (2005), Paraguay (2011), Colombia (2009–2017–2018), Republic of Korea (2010, 2014) and others, have experienced the introduction of FMDV [1]. Measures to avoid introduction of FMDV and exposure of susceptible animals as well as establishment of early detection systems and contingency plans are needed to control and prevent outbreak of FMD. The last FMD outbreak in Argentina was recorded in 2006 [1] and currently the whole country holds the FMD-free status. Argentina and other South American countries achieved FMD eradication through control strategies essentially based on systematic and mandatory vaccination of cattle.

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