Porcine circovirus‐2 in Africa: Identification of continent‐specific clusters and evidence of independent viral introductions from Europe, North America and Asia

Abstract

Porcine circovirus‐2 (PCV‐2) is associated with several disease syndromes in domestic pigs that have a significant impact on global pig production and health. Currently, little is known about the status of PCV‐2 in Africa. In this study, a total of 408 archived DNA samples collected from pigs in Burkina Faso, Cameroon, Cape Verde, Ethiopia, the Democratic Republic of the Congo, Mozambique, Nigeria, Senegal, Tanzania and Zambia between 2000 and 2018 were screened by PCR for the presence of PCV‐2. Positive amplicons of the gene encoding the viral capsid protein (ORF2) were sequenced to determine the genotypes circulating in each country. Four of the nine currently known genotypes of PCV‐2 were identified (i.e. PCV‐2a, PCV‐2b, PCV‐2d and PCV‐2 g) with more than one genotype being identified in Burkina Faso, Ethiopia, Nigeria, Mozambique, Senegal and Zambia. Additionally, a phylogeographic analysis which included 38 additional ORF2 gene sequences of PCV‐2s previously identified in Mozambique, Namibia and South Africa from 2014 to 2016 and 2019 to 2020 and available in public databases, demonstrated the existence of several African‐specific clusters and estimated the approximate time of introduction of PCV‐2s into Africa from other continents. This is the first in‐depth study of PCV‐2 in Africa and it has important implications for pig production at both the small‐holder and commercial farm level on the continent.

A Phylogeographic Analysis of Porcine Parvovirus 1 in Africa

“…Similarly, Asia and China in particular, have played an increasing role in African countries’ economies [ 34 ], including the agricultural sector, thus increasing the risk of direct or indirect contact between animals and their by-products. Similar connections have been reported for several infections affecting both companion animals and livestock [ 35 , 36 ]. The high environmental resistance of PPV1 could also point to more obscure, indirect, and long-distance transmission pathways.…”

Molecular Epidemiology and Genetic Characterization of PCV2 Circulating in Wild Boars in Southwestern Ethiopia

“…a lower virulence, were also involved remains to be established. A previous study reported the detection of PCV2a and PCV2b genotypes in Ethiopia [ 10 ]; unfortunately, the low viral titer hindered the sequencing of all positive samples. In one of the sequenced samples, the presence of PCV2b was confirmed, while the other 4 sequences were classified as PCV2d, further demonstrating the breadth of genetic heterogeneity featuring Ethiopian molecular epidemiology.…”

“…However, a previous study estimated a likely PCV2b introduction in Ethiopia from Asia [ 10 ]. Therefore, a similar importation pathway could be expected.…”

“…In fact, despite PCV2 being identi ed as a swine pathogen in the late 90s, retrospective studies and analysis based on the molecular clock revealed a much more ancient origin and undetected circulation [6]. Similarly, di erent studies have revealed PCV2 infection in wild boars and other wild animals, although negligible evidence of clinical signs has been provided in these species [7][8][9][10][11][12][13]. Also, extensively raised pigs appeared less a ected.…”

“…The detection of PCV2c, previously considered extinct, in feral pigs in the Brazilian region of Pantanal and in Namibian warthogs is probably the most obvious example [ 17 , 18 ]. Also, PCV2g has been reported in African pigs [ 10 ]. Therefore, the capability of these often-neglected species and countries to host minor or even currently undetected genotypes and genetic variants appears clear, and they could affect and contribute to PCV2 evolution.…”