viruses Brief Report Infectivity of an Infectious Clone of Banana Streak CA Virus in A-Genome Bananas (Musa acuminata ssp.) Anthony P. James 1,†,‡ , Dawit B. Kidanemariam 1,‡ , Sharon D. Hamill 2 , James L. Dale 1 and Robert M. Harding 1, *   Citation: James, A.P.; Kidanemariam, D.B.; Hamill, S.D.; Dale, J.L.; Harding, R.M. Infectivity of an Infectious Clone of Banana Streak CA Virus in A-Genome Bananas (Musa acuminata ssp.). Viruses 2021, 13, 1071. https:// doi.org/10.3390/v13061071 Academic Editor: K. Andrew White Received: 5 May 2021 Accepted: 2 June 2021 Published: 4 June 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Centre for Agriculture and the Bioeconomy (CAB), Queensland University of Technology (QUT), Brisbane, QLD 4001, Australia; ap.james@connect.qut.edu.au (A.P.J.); d.kidanemariam@qut.edu.au (D.B.K.); j.dale@qut.edu.au (J.L.D.) 2 Department of Agriculture and Fisheries (DAF), Maroochy Research Facility, Nambour, QLD 4560, Australia; Sharon.Hamill@daf.qld.gov.au * Correspondence: r.harding@qut.edu.au; Tel.: +61-7-31381379 † Current address: Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013 Crete, Greece. ‡ These authors contributed equally to this work. Abstract: We have characterized the complete genome sequence of an Australian isolate of banana streak CA virus (BSCAV). A greater-than-full-length, cloned copy of the virus genome was assembled and agroinoculated into five tissue-cultured plants of nine different Musa acuminata banana accessions. BSCAV was highly infectious in all nine accessions. All five inoculated plants from eight accessions developed symptoms by 28 weeks post-inoculation, while all five plants of M. acuminata AA subsp. zebrina remained symptomless. Symptoms were mild in six accessions but were severe in Khae Phrae (M. acuminata subsp. siamea) and the East African Highland banana accession Igisahira Gisanzwe. This is the first full-length BSCAV genome sequence reported from Australia and the first report of the infectivity of an infectious clone of banana streak virus. Keywords: badnavirus; banana; banana streak virus; Caulimoviridae; infectious clone 1. Introduction Bananas (Musa spp.) are hosts to several badnavirus species referred to collectively as banana streak viruses (BSVs), with nine species currently recognized by the International Committee on Taxonomy of Viruses (ICTV) [1]. BSVs occur in most banana-producing countries where infection typically results in narrow, discontinuous or continuous, chlorotic and necrotic streaks which run parallel to the leaf veins [2]. Symptoms can vary consid- erably, however, and can also include large chlorotic areas on the leaf lamina, stunting, pseudostem splitting, internal necrosis, cigar leaf necrosis and plant death. Symptom expression is also influenced by a range of factors, including host cultivars, virus species and climatic conditions [3]. BSVs are members of the genus Badnavirus, family Caulimoviridae which have a double- stranded, circular DNA genome of about 7–9 kbp typically containing three open reading frames (ORFs) [4]. ORF 3 encodes a large polyprotein of ~200 kDa that is processed into several mature functional proteins. The reverse transcriptase (RT)/ribonuclease H (RNase H)-coding sequence of ORF 3 is the most highly conserved region, and a nucleotide sequence difference of more than 20% in this region is used for demarcation of species in the genus [1]. Infectious clones have been reported for several badnaviruses, including the Com- melina yellow mottle virus (ComYMV), Citrus yellow mosaic virus (CYMV), Cacao swollen shoot virus (CSSV), Sugarcane bacilliform virus (ScBV) and Taro bacilliform virus [5–9]. These have been used for a variety of purposes, including the investigation of infectivity Viruses 2021, 13, 1071. https://doi.org/10.3390/v13061071 https://www.mdpi.com/journal/viruses