Detection of rotavirus antigen from calves in rural areas of the North-West Province, South Africa
Diarrhoea remains a major problem in animals worldwide with rotavirus being one of the most common pathogens associated with its pathology. The clinical signs and outcomes of the diseases are not different in most species and severity may range from an asymptomatic or sub-clinical condition to severe enteritis. Meanwhile in domestic animals and humans, rotavirus diarrhoea is a major cause of death to millions of infants in developing countries and severe losses to livestock. Substantial economic loss occurs due to increased mortality, treatment costs and reduced growth rates of animals as a result of rotavirus infection. The purpose of the present study was to detect the presence of rotavirus in diarrhoeal stools collected from calves below the age of 3 months in the rural areas of the North-West Province of South Africa. In this study 200 diarrhoeal samples were randomly collected from calves below the age of 3 months from the rural areas of Mafikeng, between 2015 and 2017. Collection was done in different seasons i.e. winter and summer. Out of the 200 diarrhoeal samples collected, 108 (54%) samples were from male calves and the remaining 92 (46%) were from female calves. The screening methods used included the Vikia Rota-Adena test kit, enzyme immunoassay (EIA), electron microscopy and the polyacrylamide gel electrophoreses (PAGE). Polymerase Chain Reaction (PCR) and the Sequencing (Sanger) methods were applied for confirmation purposes. The Vikia Rota-Adena kit was able to detect 36/200 ( 18%) positive samples, indicating rotavirus exposure. EIA was applied only on 50 samples (36 from Vikia positive and 14 equivocal samples) and none were positive. From the 50 samples only 2/50 (4%) were confirmed positive by RT-PCR i.e. samples C6 and 101 , and showed the presence of the 11 segmented genome (characteristics of rotavirus) when tested by PAGE. Morphological studies conducted using Transmission Electron Microscopy yielded rotaviral-like particles. The 2 samples confirmed positive by RT-PCR, were genotyped using multiplex RT-PCR and sample C6 was identified as genotype G10P11 while sample101 could not be typed. Samples C6 and 101 were also taken for sequencing and only sample 101 was successfully sequenced and confirmed to be G12P8 genotype. These results show the importance of using more than one method for genotyping lest you miss some types. From the 200 samples that were subjected to lab techniques, we report an overall presence of 1 % (2/200). The conclusion from this study might be two fold, viz., a larger sample size might have yielded a different result or that the current prevalence status of rotavirus amongst calves in the rural areas around Mafikeng is low and might not be a cause for concern when compared with various studies conducted globally, especially considering the fact that rotavirus is also self-limiting.