Bluetongue virus infection in naïve cattle: Identification of circulating serotypes and associated Culicoides biting midge species in Trinidad

Abstract

HighlightsHigh prevalence of bluetongue virus in Trinidad.Identification of six bluetongue virus serotypes in Trinidad.First isolation of BTV-2 and BTV-5 in Trinidad.Risk of emergence of reassortant viruses.

Identification and characterization of epizootic hemorrhagic disease virus serotype 6 in cattle co-infected with bluetongue virus in Trinidad, West Indies

“…After initial infection, Ct levels slowly increased over the six-month study period (corresponding to decreasing EHDV-RNA levels), indicating that a single EHDV serotype was likely to be circulating in Trinidad, as was confirmed by the sole identification of EHDV-6 in the cattle. This was in contrast to the kinetics of infection observed for BTV in the same cohort of cattle over the same time period, where multiple serotypes of BTV were circulating in the cattle (Brown-Joseph et al, 2017). Epizootic haemorrhagic disease virus antibodies appeared in the cattle over a longer time period, with BTV antibodies being first-detected in 100% of the cattle by month three, as opposed to by month six for EHDV.…”

“…No new seroconversions occurred in month one, one cow seroconverted in month two, eleven cattle seroconverted in month three, a further six cattle seroconverted in month four, nine cattle seroconverted in month five and the remaining three cattle seroconverted in month six. The time period to seroconversion for EHDV was longer than for BTV (data taken from Brown-Joseph et al, 2017) in the same cohort of cattle (Fig. 1).…”

“…1 A: Percentage of cattle positive for antibodies (Ab) and RNA for both EHDV and BTV time of arrival in Trinidad (month 0) to the last month of blood collection (month 6). (BTV Ct values from their were taken from Brown-Joseph et al, 2017). B: Ct values measured by EHDV group-specific rRT-PCRs on blood samples taken from the first month of virus detection to the last month of blood collection (month 6).…”

“…In June 2013 the government of TTO imported 60 dairy cattle from the USA to improve genetic livestock. This provided an opportunity to investigate the endemicity of Culicoides -borne Orbiviruses in Trinidad, particularly those that affect livestock trade, such as BTV and EHDV (Brown-Joseph et al, 2017; Verdezoto et al, 2017). Although EHDV infections in cattle are typically asymptomatic, certain EHDV serotypes (2, 6 and 7) have caused serious clinical disease in domestic cattle (Cêtre-Sossah et al, 2014; Allison et al, 2010; Temizel et al, 2009; Anthony et al, 2009; Yadin et al, 2008; Gaydos et al, 2004; Bréard et al, 2004), which can impact beef and milk production (CFSPH, 2016; Kedmi et al, 2010).…”

Simultaneous Detection of Bluetongue Virus Serotypes Using xMAP Technology

“…Typically, serotype-specific RT-qPCR is performed to determine the dominant serotype (to infer clinical significance) rather than screen samples for all possible serotypes. Although infections with multiple serotypes have been identified in field samples [ 39 , 40 , 41 ], these may be underreported when using singleplex RT-qPCR detection strategies where samples may only be tested for a limited number of serotypes. Infection of ruminants with multiple BTV serotypes can lead to the emergence of novel, possibly more virulent, BTV strains [ 42 ].…”