Methods: DNA was extracted from peripheral blood mononuclear cells from transplant patients (with and without biopsy-proven PTLD) and persons with infectious mononucleosis (IM). Following amplification of the BZLF1 gene, dideoxy DNA sequencing was done on all 3 exons of the gene. Nucleotide sequences were aligned and compared with the EBV reference strain, B95.8. Data were descriptively summarized and medians and proportions compared using a non-parametric procedure and Fisher’s exact test, respectively. For this report, we examined the presence of mutations that resulted in a specific protein change (non-synonymous mutations).
Results: Sequences from 22 patients were studied; 6 sequences from patients with PTLD, 7 from transplant patients without PTLD and 9 from patients with IM. Most variations were in exon 1, where the median numbers of non-synonymous single nucleotide variations (SNVs) were: IM 0 (range 0-6), transplant without PTLD 0 (range 0-6) and PTLD patients 5 (range 0-8). Among transplant patients, 4 of 6 PTLD patients (66.7%) had at least 1 mutation compared with 1/7 non-PTLD patients (14.3%) (P=.1). Furthermore, PTLD patients were more likely to have SNVs compared with transplant patients without PTLD (23/78 vs 6/91, P = .0001), where the denominator is the nucleotide count within the exon. A pattern of 5 SNVs within each sample was seen in 22% of IM patents, 0% of transplant patients without PTLD and 50% of PTLD patients.
Conclusion: We have documented differences in the EBV BZLF1 variants among the study groups. A polymorphism pattern was identified among the disease states. Differences were observed between transplant patients with and without PTLD; thus providing the impetus for further research to define cause and effect relationships and whether the presence of BZLF1 variants might indicate an increased likelihood of PTLD.
N. Khodai-Booran, None
T. Paton, None
A. Dipchand, None
D. Hebert, None
V. Ng, None
M. Solomon, None