Published Date: 2008-09-09 15:00:32
Subject: PRO/PL> Banana bunchy top virus - Angola: 1st rep.
Archive Number: 20080909.2811
BANANA BUNCHY TOP VIRUS - ANGOLA: FIRST REPORT
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: August 2008
Source: British Society for Plant Pathology, New Disease Reports
(NDR) vol. 18 (August 2008-January 2009) [edited]
[Ref: P. Lava Kumar et al: First report of _Banana bunchy top virus_
in banana and plantain (_Musa_ spp.) in Angola. BSPP New Disease
Reports vol. 18]
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 [enzyme-linked immunosorbent assay]
assay using a polyclonal antiserum against _Banana bunchy top virus_
(BBTV; genus _Babuvirus_, family _Nanoviridae_).
BBTV was further confirmed by PCR [polymerase chain reaction] for a
ca 250 basepair conserved domain of BBTV DNA-R. An amplicon of the
expected size (256 bp) was sequenced. Comparisons of this sequence
showed the greatest nucleotide identity (97 percent) with a BBTV
isolate from Hawaii and 96 to 97 percent similarity with BBTV
isolates of a 'South Pacific Group.' By contrast, there was less
similarity (85 to 90 percent) with isolates of the 'Asian Group,'
indicating that the virus isolate from Angola falls within the South
Pacific Group (Figure 2).
This is the 1st report of BBTV occurrence in Angola. Together with
previous reports of BBTV in southern and central African countries,
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.
Figure 1: stunted plants, shorter and narrower leaves, yellowing and
curling of leaf margins of BBTV-infected banana plants in Angola.
Figure 2: most parsimonious tree of various BBTV isolates. The
position of BBTV-Angolan isolate is highlighted.
[BBTV is the only member of the genus _Babuvirus_, family
_Nanoviridae_. The name abaca bunchy top virus has been listed as a
synonym by the ICTV (International Committee on Taxonomy of Viruses)
and is often used for BBTV strains affecting _Musa textilis_ (abaca,
Manila hemp) in the Philippines. BBTV only affects _Musa_ spp.
causing chlorosis, stunting, and death of the host plant. The virus
is spreading in Africa, Australasia, and the Pacific Islands.
BBTV is transmitted by the aphid _Pentalonia nigronervosa_ (banana
aphid) in a persistent manner. The vector is itself a pest of banana
as well as many other tropical and subtropical plants and is found in
all banana growing areas. Infectious insects may be spread on plant
material. BBTV cannot be transmitted by mechanical inoculation.
Disease management includes vector control, removal of inoculum, use
of clean planting material, and frequent scouting for new outbreaks.
Planting tolerant varieties will enable some crop production in
infected areas, but these cultivars may still serve as virus
Most of today's cultivated bananas are sterile triploids related to
either _Musa acuminata_ and/or _M. balbisiana_. The specific genetic
set-up of a cultivar is indicated by the letters A and B.
Provinces of Angola:
BBTV symptoms on whole banana plants:
Symptoms on fruit:
BBTV fact sheets with pictures:
Information on BBTV:
Information on BBTV aphid vector:
History and genetics of cultivated banana:
<http://www.ncbi.nlm.nih.gov/ICTVdb/index.htm>. - Mod.DHA]