Reactivation of occult hepatitis B virus infection following cytotoxic lymphoma therapy in an anti-HBc negative patient.

Screening hepatitis B virus (HBV) surface antigen (HBsAg) and HBV core antibody (anti-HBc) is recommended prior to cytotoxic or immunosuppressive therapy. This case describes an anti-HBc negative, DNA positive occult HBV infection in a 71-year-old Caucasian male following rituximab-based treatment for follicular lymphoma. Pre-screening serology indicated negative HBsAg and anti-HBc. However, following sequential treatment cycles the patient developed weak HBsAg with a low HBV DNA load (<1,000 IU/ml), but remained anti-HBc negative. The DNA load peaked 5 months later (>1 × 10(6) IU/ml) and he was subsequently treated with Tenofovir. Currently the patient remains anti-HBc negative, and is anti-HBe negative, anti-HBs negative, HBeAg positive. No clinical or biochemical evidence of hepatitis has occurred. Sequencing and phylogenetic analysis identified the HBV genosubtype as D4, most probably acquired some years ago during a stay in Papua New Guinea, in spite of prior hepatitis B vaccination. Four amino acid substitutions were detected within the HBsAg loop yet none in the core protein. This case questions the dependability of anti-HBc testing and highlights the role of HBV DNA testing prior to and throughout cytotoxic or immunosuppressive regimes. As this case exemplifies, vaccination protects against clinical infection but may not exclude seronegative occult infection with the possibility of reactivation.

Development and assay of RNA transcripts of enterovirus species A to D, rhinovirus species a to C, and human parechovirus: assessment of assay sensitivity and specificity of real-time screening and typing methods.

Nucleic acid amplification methods such as the PCR have had a major impact on the diagnosis of viral infections, often achieving greater sensitivities and shorter turnaround times than conventional assays and an ability to detect viruses refractory to conventional isolation methods. Their effectiveness is, however, significantly influenced by assay target sequence variability due to natural diversity and rapid sequence changes in viruses that prevent effective binding of primers and probes. This was investigated for a diverse range of enteroviruses (EVs; species A to D), human rhinoviruses (HRVs; species A to C), and human parechovirus (HPeV) in a multicenter assay evaluation using a series of full-length prequantified RNA transcripts. RNA concentrations were quantified by absorption (NanoDrop) and fluorescence methods (RiboGreen) prior to dilution in buffer supplemented with RNase inhibitors and carrier RNA. RNA transcripts were extremely stable, showing minimal degradation after prolonged storage at temperatures between ambient and -20°C and after multiple freeze-thaw cycles. Transcript dilutions distributed to six referral laboratories were screened by real-time reverse transcriptase PCR assays using different primers and probes. All of the laboratories reported high assay sensitivities for EV and HPeV transcripts approaching single copies and similar amplification kinetics for all four EV species. HRV detection sensitivities were more variable, often with substantially impaired detection of HRV species C. This could be accounted for in part by the placement of primers and probes to genetically variable target regions. Transcripts developed in this study provide reagents for the ongoing development of effective diagnostics that accommodate increasing knowledge of genetic heterogeneity of diagnostic targets.

Role of vascular endothelial growth factor and placental growth factors during retinal vascular development and hyaloid regression.

PURPOSE: Vascular endothelial growth factor (VEGF)-A and placental growth factor (PlGF) are members of a large group of homologous peptides identified as the VEGF family. Although VEGF-A is known to act as a potent angiogenic peptide in the retina, the vasoactive function of PlGF in this tissue is less well defined. This study has sought to elucidate the expression patterns and modulatory role of these growth factors during retinal vascular development and hyaloid regression in the neonatal mouse. METHODS: C57BL6J mice were killed at postnatal days (P)1, P3, P5, P7, P9, and P11. The eyes were enucleated and processed for in situ hybridization and immunocytochemistry and the retinas extracted for total protein or RNA. Separate groups of neonatal mice were also injected intraperitoneally daily from P2 through P9 with either VEGF-neutralizing antibody, PlGF-neutralizing antibody, isotype immunoglobulin (Ig)-G, or phosphate-buffered saline (PBS). The mice were then perfused with fluorescein isothiocyanate (FITC)-dextran, and the eyes were subsequently embedded in paraffin wax or flat mounted. RESULTS: Quantitative (real-time) reverse transcription-polymerase chain reaction (RT-PCR) demonstrated similar expression patterns of VEGF-A and PlGF mRNA during neonatal retinal development, although the fluctuation between time periods was greater overall for VEGF-A. The localization of VEGF-A and PlGF in the retina, as revealed by in situ hybridization and immunohistochemistry, was also similar. Neutralization of VEGF-A caused a significant reduction in the hyaloid and retinal vasculature, whereas PlGF antibody treatment caused a marked persistence of the hyaloid without significantly affecting retinal vascular development. CONCLUSIONS: Although having similar expression patterns in the retina, these growth factors appear to have distinct modulatory influences during normal retinal vascular development and hyaloid regression.

A touchdown nucleic acid amplification protocol as an alternative to culture backup for immunofluorescence in the routine diagnosis of acute viral respiratory tract infections.

BACKGROUND: Immunofluorescence and virus culture are the main methods used to diagnose acute respiratory virus infections. Diagnosing these infections using nucleic acid amplification presents technical challenges, one of which is facilitating the different optimal annealing temperatures needed for each virus. To overcome this problem we developed a diagnostic molecular strip which combined a generic nested touchdown protocol with in-house primer master-mixes that could recognise 12 common respiratory viruses. RESULTS: Over an 18 month period a total of 222 specimens were tested by both immunofluorescence and the molecular strip. The specimens came from 103 males (median age 3.5 y), 80 females (median age 9 y) and 5 quality assurance scheme specimens. Viruses were recovered from a number of specimen types including broncho-alveolar lavage, nasopharyngeal secretions, sputa, post-mortem lung tissue and combined throat and nasal swabs. Viral detection by IF was poor in sputa and respiratory swabs. A total of 99 viruses were detected in the study from 79 patients and 4 quality control specimens: 31 by immunofluorescence and 99 using the molecular strip. The strip consistently out-performed immunofluorescence with no loss of diagnostic specificity. CONCLUSIONS: The touchdown protocol with pre-dispensed primer master-mixes was suitable for replacing virus culture for the diagnosis of respiratory viruses which were negative by immunofluorescence. Results by immunofluorescence were available after an average of 4-12 hours while molecular strip results were available within 24 hours, considerably faster than viral culture. The combined strip and touchdown protocol proved to be a convenient and reliable method of testing for multiple viruses in a routine setting.

Rising incidence of Pneumocystis jirovecii pneumonia suggests iatrogenic exposure of immune-compromised patients may be becoming a significant problem.

Against a background of point-source outbreaks of Pneumocystis pneumonia (PCP) in renal transplant units in Europe, we undertook a retrospective 3 year observational review of PCP in Northern Ireland. This showed an unexpected increase in incidence, with a mortality rate of 30 %. Fifty-one cases were confirmed compared to 10 cases confirmed in the preceding 7 years. Where undiagnosed HIV infection had previously been the main risk factor for PCP, this was now equally matched by chemotherapy for haematological and non-haematological malignancy and immune suppression for a range of autoimmune conditions. Congenital immunodeficiency and transplantation were less common predisposing factors, but renal grafts also showed a rising incidence. Asymptomatic carriage was uncommon. At presentation both upper and lower respiratory samples were of equal use in establishing the diagnosis, and treatment resulted in rapid clearance. These data suggest the need for considering PCP in at-risk patients, reviewing its mode of acquisition and whether iatrogenic colonization is a treatable pre-condition.

Association of the G4 rotavirus genotype with gastroenteritis in adults.

Rotavirus is the most common etiological cause of acute viral gastroenteritis in infants and young children worldwide, yet its role in the adult population is less well understood. We have recently identified rotavirus as the causative agent of severe diarrhea in adults, specifically in two gastroenteritis outbreaks in separate care for the elderly homes. Strain typing has shown the continued presence of P[8]G1, the emergence of P[8]G9, and the reemergence of P[8]G4. A total of 26 community cases and 6 outbreak cases of rotavirus infection, positive via a molecular screening assay, were subsequently amplified using VP4 and VP7 specific primers (Con2/Con3 and 1A/1B primer sets, respectively). The age range of patients investigated was from <1 year to 89 years. The resulting PCR products were cloned into TOPO10 PCR IV vector and sequenced to give the P- and G-type accordingly. All sequence data were subjected to BLAST analysis. Three different rotavirus types P[8]G1, P[8]G4, and P[8]G9 were identified. Types P[8]G1 and P[8]G9 were identified as circulating within the community, whereas the third type P[8]G4 was identified only in an elderly care outbreak. The identification of G9 rotaviruses supports evidence of emergence of the genotype on a global scale.