Abstract
BackgroundSimbu serogroup viruses of the Orthobunyavirus genus (Family Peribunyaviridae) include teratogenic pathogens that cause severe economic losses, abortions, stillbirths and congenital abnormalities in ruminants worldwide. Although they were initially isolated from ruminants and Culicoides biting midges about five decades ago in Nigeria, there is no current information on their prevalence and geographical distribution despite reports of abortions and congenital malformations in the country’s ruminant population. Here, apparently healthy cattle and sheep obtained from eight states in the three major vegetation zones of Nigeria were screened for the presence of specific neutralizing antibodies against Schmallenberg virus (SBV), Simbu virus (SIMV) and Shamonda virus (SHAV).ResultsUsing a cross-sectional design, 490 cattle and 165 sheep sera were collected between 2012 and 2014 and tested by a commercial SBV ELISA kit which enables the detection of antibodies against various Simbu serogroup viruses. The seropositivity rates for cattle and sheep were 91.2% and 65.4%, respectively. In cattle, there was no association between ELISA seropositivity and vegetation zone. However, the prevalence of anti-Simbu serogroup antibodies was significantly higher in Ebonyi State compared to other states in the rainforest vegetation zone. The seroprevalence was significantly higher in sheep obtained from live animal markets compared to farms (OR = 5.8). Testing of 20 selected ELISA-positive sera by serum neutralisation test showed that all were positive for one or more of SBV, SIMV and SHAV with the highest titres obtained for SHAV. Antibodies to SBV or a closely related virus were detected in the Sudan savannah and rainforest zones, anti-SIMV antibodies were detected only in the rainforest zone, while anti-SHAV antibodies were found in the three vegetation zones.ConclusionThe findings of this study reveal that following the early isolation of Simbu serogroup viruses in Nigeria in the 1960s, members of this virus group are still circulating in the country. Specifically, SBV, SIMV and SHAV or closely related viruses infect cattle and sheep across the three vegetation zones of Nigeria suggesting that insect vector activity is extensive in the country. The exact vegetation zone where the animals became exposed to the viruses could, however, not be determined in this study.
Highlights
Simbu serogroup viruses of the Orthobunyavirus genus (Family Peribunyaviridae) include teratogenic pathogens that cause severe economic losses, abortions, stillbirths and congenital abnormalities in ruminants worldwide
The Simbu serogroup comprises at least 25 viruses that are currently divided into seven species, namely: Akabane virus (AKAV), Manzanilla virus, Oropouche virus, Sathuperi virus (SATV), Shamonda virus (SHAV), Shuni virus (SHUV) and Simbu virus (SIMV) [1, 2]
Simbu serogroup enzyme-linked immunosorbent assay (ELISA) Out of 490 cattle sera tested for anti-Simbu serogroup antibodies with the ELISA, 447 (91.2%), 20 (4.1%) and 23 (4.7%) were positive, doubtful and negative, respectively, while of the 165 sheep sera tested, 108 (65.4%), 11 (6.7%) and 46 (27.9%) were positive, doubtful and negative, respectively
Summary
Simbu serogroup viruses of the Orthobunyavirus genus (Family Peribunyaviridae) include teratogenic pathogens that cause severe economic losses, abortions, stillbirths and congenital abnormalities in ruminants worldwide. They were initially isolated from ruminants and Culicoides biting midges about five decades ago in Nigeria, there is no current information on their prevalence and geographical distribution despite reports of abortions and congenital malformations in the country’s ruminant population. The Simbu serogroup comprises at least 25 viruses that are currently divided into seven species, namely: Akabane virus (AKAV), Manzanilla virus, Oropouche virus, Sathuperi virus (SATV), Shamonda virus (SHAV), Shuni virus (SHUV) and Simbu virus (SIMV) [1, 2] Several of these Simbu serogroup viruses are known to be teratogenic in ruminants [6] causing abortions, stillbirths and congenital abnormalities. Different assays including serum neutralization test (SNT), immunofluorescence (IF) assay and enzyme-linked immunosorbent assay (ELISA) have been used for the serologic detection of previous infections with these viruses [16, 20,21,22], specific detection of antibodies against them can be achieved by SNT [20]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have