Natural Infection of Swinglea glutinosa by the Citrus leprosis virus Cytoplasmic Type (CiLV-C) in Colombia.

Swinglea glutinosa (Blanco) Merr., a perennial plant in the family Rutaceae, is originally from southeast Asia but which is now grown worldwide. In Colombia, it is used as an ornamental and principally as a living fence around rural properties and farms in several regions of the country. Citrus leprosis virus cytoplasmic type (CiLV-C) was recently detected in orange groves of the Colombian Piedmont eastern plains, an area known as the Llanos Orientales (2). Because of the potential for country-wide infection of citrus, some measures are being taken to avoid CiLV-C spread to other regions of Colombia. Further surveys made from June to December 2005 to evaluate the extent of the spread of CiLV-C in the Llanos Orientales revealed some plants in S. glutinosa hedges surrounding citrus orchards exhibiting chlorotic spots and ringspots of varied size on the leaves, similar to those caused by CiLV-C on sweet oranges leaves. These plants were found near citrus orchards in the municipalities of Guamal and in some urban areas of Villavicencio City in the Meta Department. The possibility that these symptoms were caused by CiLV-C was investigated soon after sample collection by the same procedures as described previously for sweet orange (2). In the leaf lesions of S. glutinosa, typical bacilliform particles and dense cytoplasmic viroplasm were found with electron microscopy. Total RNA extracted from symptomatic leaves was subjected to reverse transcription-PCR (RT) using primers (Fwd. 5'GATACGGGACGCATAACA-3'/Rev. 5'-TTCTGGCTCAACATCTGG-3') that specifically amplify a region within the CiLV-C putative methyltransferase gene and this yielded a single fragment of the expected 402 bp (3). Analysis of the consensus sequence derived from 20 RT-PCR products (GenBank Accession No. EU689106) showed 96% nucleotide and 92% amino acid sequence identity to the sequence of a Brazilian CiLV-C isolate (GenBank Accession Nos. DQ352194.1 and YP_654565.1), respectively. Recently, published work described mite transmission of CiLV-C to some nonrutaceous plants (1), but to our knowledge, this is the first report of a nonCitrus rutaceous plant naturally infected by CiLV-C. Mites found in citrus orchards and previously identified as Brevipalpus phoenicis (Geijskes) (2), which are likely the most important vector of CiLV-C in citrus in Colombia, were observed feeding on healthy and symptomatic S. glutinosa, indicating that S. glutinosa is a host for B. phoenicis. Because the use of S. glutinosa as a living fence or hedge is a common practice in Colombia, CiLV-C-infected S. glutinosa plants may play a role in the epidemiology of leprosis in commercial citrus by serving as an inoculum source for this lethal virus. References: (1) M. Bastianel et al. Summa Phytopathol. 32:211, 2006. (2) G. A. León et al. Plant Dis. 90:682, 2006. (3) E. C. Locali et al. Plant Dis. 87:1317, 2003.

Molecular genetics of palmitoyl-protein thioesterase deficiency in the U.S.

Mutations in a newly described lysosomal enzyme, palmitoyl-protein thioesterase (PPT), were recently shown to be responsible for an autosomal recessive neurological disorder prevalent in Finland, infantile neuronal ceroid lipofuscinosis. The disease results in blindness, motor and cognitive deterioration, and seizures. Characteristic inclusion bodies (granular osmiophilic deposits [GROD]) are found in the brain and other tissues. The vast majority of Finnish cases are homozygous for a missense mutation (R122W) that severely affects PPT enzyme activity, and the clinical course in Finnish children is uniformly rapidly progressive and fatal. To define the clinical, biochemical, and molecular genetic characteristics of subjects with PPT deficiency in a broader population, we collected blood samples from U.S. and Canadian subjects representing 32 unrelated families with neuronal ceroid lipofuscinosis who had GROD documented morphologically. We measured PPT activity and screened the coding region of the PPT gene for mutations. In 29 of the families, PPT deficiency was found to be responsible for the neurodegenerative disorder, and mutations were identified in 57 out of 58 PPT alleles. One nonsense mutation (R151X) accounted for 40% of the alleles and was associated with severe disease in the homozygous state. A second mutation (T75P) accounted for 13% of the alleles and was associated with a late onset and protracted clinical course. A total of 19 different mutations were found, resulting in a broader spectrum of clinical presentations than previously seen in the Finnish population. Symptoms first appeared at ages ranging from 3 mo to 9 yr, and about half of the subjects have survived into the second or even third decades of life.

Mutations in the palmitoyl-protein thioesterase gene (PPT; CLN1) causing juvenile neuronal ceroid lipofuscinosis with granular osmiophilic deposits.

A subtype of neuronal ceroid lipofuscinosis (NCL) is well recognized which has a clinical course consistent with juvenile NCL (JNCL) but the ultrastructural characteristics of infantile NCL (INCL): granular osmiophilic deposits (GROD). Evidence supporting linkage of this phenotype, designated vJNCL/GROD, to the INCL region of chromosome 1p32 was demonstrated (pairwise lod score with D1S211 , Z max = 2.63, straight theta = 0.00). The INCL gene, palmitoyl-protein thioesterase (PPT ; CLN1), was therefore screened for mutations in 11 vJNCL/GROD families. Five mutations in the PPT gene were identified: three missense mutations, Thr75Pro, Asp79Gly, Leu219Gln, and two nonsense mutations, Leu10STOP and Arg151STOP. The missense mutation Thr75Pro accounted for nine of the 22 disease chromosomes analysed and the nonsense mutation Arg151STOP for seven. Nine out of 11 patients were shown to combine a missense mutation on one disease chromosome with a nonsense mutation on the other. Mutations previously identified in INCL were not observed in vJNCL/GROD families. Thioesterase activity in peripheral blood lymphoblast cells was found to be markedly reduced in vJNCL/GROD patients compared with controls. These results demonstrate that this subtype of JNCL is allelic to INCL and further emphasize the correlation which exists between genetic basis and ultrastructural changes in the NCLs.