First report of Banana bunchy top virus in banana and plantain (Musa spp.) in Angola

In April 2008 in the northern Provinces of Angola, banana (AAA genome) and plantain (AAB genome) plants (Musa spp.) with severe stunting and moderate to severe leaf symptoms typical of banana bunchy top disease were observed to be widespread in farmers’ fields in Kirimadhola village in the Ndalatando region in Cuanza Norte Province, and Tokosiala, Buku li Tsiela and Conde villages in the Landana region of Cabinda Province. Leaf extracts from symptomatic plants were positive in an ELISA assay (OD405nm of infected ≥2 x healthy controls) using a polyclonal antiserum (NCBR, India) raised against Banana bunchy top virus (BBTV; genus Babuvirus, family Nanoviridae).

BBTV was further confirmed by PCR using total DNA extracted from symptomatic plant samples and oligonucleotide primers specific for a ca 250 bp conserved domain of BBTV DNA-R, according to published PCR protocols (Mansoor et al., 2005). An amplicon of the expected size (256 bp) was cloned into pGEM-T Easy Vector (Promega, UK) and two independent clones were sequenced in both directions (GenBank Acc. No. EU851977).

Comparisons of this sequence using a BLAST search showed the greatest nucleotide identity (97%) with a BBTV isolate from Hawaii (U18077) and 96 to 97% similarity with BBTV isolates of a ‘South Pacific Group’. By contrast, there was less similarity (85 to 90%) with isolates of the ‘Asian Group’, indicating that the virus isolate from Angola falls within the South Pacific Group (Figure 2). This is the first report of BBTV occurrence in Angola. Together with previous reports of BBTV in southern and central African countries (CABI, 2005; Kenyon et al., 1998), this report provides evidence for the widespread occurrence of BBTV in the region. The presence of both the virus and its aphid vector, Pentalonia nigronervosa, in Africa has the potential to cause widespread damage to banana, especially on the highly susceptible Cavendish types. This highlights the urgent need for intensive surveys to assess the extent of the geographic spread and severity of BBTV in Africa and the implementation of phytosanitary measures to eradicate infected plants.