We report here the complete genome sequence of “Candidatus Liberibacter africanus” strain PTSAPSY. The 1,192,232-bp genome with 34.5% G+C content comprises 1,017 open reading frames, 44 tRNAs, and three complete rRNAs in a circular chromosome.

Citrus tristeza virus (CTV) causes severe losses in grapefruit production in South Africa and requires mild strain cross-protection to maintain production. Unfortunately cross-protection breakdown of the preimmunizing CTV grapefruit mild source GFMS12 is prevalent in grapefruit in South Africa. The CTV genotype composition of the GFMS12 population inoculated onto different hosts was determined by sequencing part of ORF1a and the p23 gene of multiple clones from each plant. Analysis of the GFMS12 population in Mexican lime, Marsh and Star Ruby grapefruit varieties, revealed that at least four genotypes occur in the GFMS12 population, and that genotype compositions differed amongst the populations in different host plants.Single aphid transmitted sub-isolates derived from the GFMS12 mother population on Mexican lime appeared to contain three populations of a mixture of VT-like and recombinant B165/VT-like genotypes; a mixture of recombinant RB/VT-and B165/VT-like genotypes; and a single recombinant B165/VT-like genotype. This study underlines the importance of determining the genotype composition of a potential CTV pre-immunizing source on a range of inoculated host species before utilization.

Antibody-directed enzyme prodrug therapy (ADEPT) targets an enzyme selectively to a tumor where it converts a relatively non-toxic prodrug to a potent cytotoxic drug. Previous clinical work using antibody-enzyme chemical conjugates has been limited by the moderate efficiency of tumor targeting of these molecules. To address this a recombinant fusion protein composed of MFE-23, an anti-carcinoembryonic antigen (CEA) single chain Fv (scFv) antibody, fused to the amino-terminus of the enzyme carboxypeptidase G2 (CPG2) has been constructed to achieve ADEPT in CEAproducing tumors. MFE-23::CPG2 fusion protein was overexpressed in Escherichia coli and purified using CEA affinity chromatography. Efficacy of MFE-23::CPG2 delivery to tumors in vivo was assessed by measuring catalytic activity after intravenous injection of purified MFE-23::CPG2 into nude mice bearing CEA-positive LS174T human colon adenocarcinoma xenografts. Recombinant MFE-23::CPG2 cleared rapidly from circulation and catalytic activity in extracted tissues showed tumor to plasma ratios of 1.5:1 (6 hr), 10:1 (24 hr), 19:1 (48 hr) and 12:1 (72 hr).125 I-MFE-23::CPG2 was retained in kidney, liver and spleen but MFE-23::CPG2 catalytic activity was not, resulting in excellent tumor to normal tissue enzyme ratios 48 hr after injection. These were 371:1 (tumor to liver), 450:1 (tumor to lung), 562:1 (tumor to kidney), 1,477:1 (tumor to colon) and 1,618:1 (tumor to spleen). Favorable tumor : normal tissue ratios occurred at early time points when there was still 21% (24 hr) and 9.5% (48 hr) of the injected activity present per gram of tumor tissue. The high tumor concentrations and selective tumor retention of active enzyme delivered by MFE-23::CPG2 establish that this recombinant fusion protein has potential to give improved clinical efficiency for ADEPT.Int.

Grapefruit cultivars are highly sensitive to CTV infections and in order to increase their productive lifespan, the Southern African citrus industry makes use cross-protection.However, CTV symptoms in the form of stem grooving is commonly observed in commercial grapefruit plantings pre-immunised with CTV GFMS 12, the initial CTV source used. Samples (n = 192) of Citrus x paradisi (Macfad.) cv. Star Ruby, preimmunised with GFMS 12 were collected from six grapefruit production areas of South Africa and Swaziland. Six samples from non-pre-immunised plants were also collected. The p33 gene was amplified and direct Sanger sequencing performed on the resulting amplicons. A sample subset was randomly selected, including three nonpre-immunised samples and subjected to Illumina MiSeq amplicon sequencing. High levels of CTV diversity were observed within trees, orchards and between orchards.Most populations were made up of a dominant component with several minor sequence types. Resistance Breaking (RB) sequences were most numerous, especially in recently planted orchards and were present within all populations. The Kpg3/SP/T3 group was the second most prevalent, with increased prevalence in older 1 D.A. Read -Plant Disease orchards. Sequences mapping to the HA 16-5, VT, AT-1, T36, Taiwan-Pum/M/T5 and T30 references, were represented sporadically within numerous collection sites.