Detection of cytomegalovirus by dot-blot DNA hybridization using probes labelled with 32P by nick translation or random hexanucleotide priming

Comparison of primer sets for detection of fecal and ocular adenovirus infection using the polymerase chain reaction

Adenoviruses of subgenus F (types 40 and 41) cause infantile gastroenteritis and adenoviruses principally of types 1-7 are found in feces during respiratory or generalized infections. Adenoviruses (mostly types 3, 4, 8, 19, or 37) are also linked with follicular or epidemic conjunctivitis. The diagnostic efficiency of the polymerase chain reaction (PCR) for adenoviruses was assessed using genus-reactive primers H1 and H2 or JCH1 and JCH2 or subgenus F-specific primers F1a and F2a. With diarrheal stool specimens containing subgenus F adenoviruses, F1a/F2a PCR achieved at least as high a positivity rate (75/76 [99%]) as electron microscopy (72/76 [95%]) and was more sensitive than polyclonal antibody-based immune electron microscopy (IEM) for subgenus identification (75/76 [99%] vs. 66/76 [87%], P = 0.008). Twenty-three subgenus F strains untypeable by monoclonal antibody-based IEM were typed as 40 (n = 4) or 41 (n = 19) by Hha I digestion of the PCR product. The genus-reactive primer pairs provided DNA amplification assays of generally equal efficiency on conjunctival swab specimens though possible nucleic acid degradation in DNA extracts during storage could have meant that JCH1/JCH2 PCR was truly the more sensitive. The use of either genus-reactive primer set on fecal specimens cannot be recommended because, although the positivity rates with subgenus F PCR positive specimens were high (70/75 [93%] for H1 and H2, 14/15 [93%] for JCH1 and JCH2), the detection rates were disappointing with similar specimens yielding nonsubgenus F adenoviruses.

Polymerase chain reaction for rapid detection of ocular adenovirus infection

Adenoviruses are associated with endemic and epidemic acute conjunctivitis, large nosocomial outbreaks reflecting virus transmission on unwashed hands or inadequately sterilised ophthalmic instruments. The polymerase chain reaction (PCR) proved more sensitive than antigen detection by immune dot-blot test for the rapid diagnosis of ocular adenovirus infection (sensitivities in a retrospective study 112/123 (91%) versus 72/123 (59%), P < 0.001). Indeed, in a prospective comparison, DNA amplification and virus isolation generated similar numbers of positive results (34 versus 32), though five PCR positive results were possibly false positives. The sensitivity of the PCR was largely independent of adenovirus subgenus or serotype, though reduced sensitivity with subgenus B strains could not be excluded. Specimen preparation for DNA amplification using a simple lysis buffer proved more effective than phenol-chloroform extraction. The immune dot-blot test gave unavoidable false positive results, but with the PCR this problem could be minimized by technical modifications. The PCR could replace antigen detection and virus isolation as the initial test for adenoviruses in conjunctival swabs, with cell culture only being retained for adenovirus serotyping in PCR positive specimens and for other viruses such as herpes simplex.

Sensitive non-isotopic DNA hybridisation assay or immediate-early antigen detection for rapid identification of human cytomegalovirus in urine

A sensitive non-radioactive DNA hybridisation assay employing digoxigenin-labelled probes was compared with immediate-early antigen detection and conventional virus isolation for the identification of human cytomegalovirus (HCMV) in 249 urine samples. Of 44 specimens yielding HCMV by virus isolation, more were positive by DNA hybridisation (32; 73%) than by immediate-early antigen detection (25; 52%) (P = 0.05). The specificity of the hybridisation assay in 45 apparently falsely positive specimens was supported by detection of HCMV DNA in 40 of these specimens using the polymerase chain reaction. Many urine specimens may thus contain large amounts of non-viable virus or free viral DNA. Evaluation of various protocols for the extraction and denaturation of virus DNA prior to hybridisation showed that proteinase K digestion with phenol/chloroform extraction was the most sensitive and reliable procedure. We conclude that the non-radioactive DNA hybridisation assay described is a potentially valuable routine diagnostic test.

Comparison of polyethylene glycol precipitation and ultracentrifugation for recovery of cytomegalovirus from urine prior to detection of DNA by dot-blot hybridisation

Polyethylene glycol (PEG) precipitation provided a useful alternative to ultracentrifugation for recovering cytomegalovirus (CMV) from clinical specimens prior to DNA hybridisation studies. The conditions for use of PEG are described. In a study of 61 urine samples from patients suspected of CMV infection 18 yielded a positive DNA hybridisation result. Fifteen were positive after both concentration procedures, two after PEG precipitation only and one after ultracentrifugation only. The DNA hybridisation results are discussed in the light of the results of virus isolation by cell culture.

Detection of cytomegalovirus DNA using probes labelled with digoxigenin

Cloned HindIII restriction fragments of cytomegalovirus (CMV) DNA (strain AD169) were labelled with biotin, digoxigenin or 32P and used as probes to detect CMV DNA. Probes biotinylated by nick translation, random hexanucleotide priming (RHP) or "photobiotin" were able to detect 10-50 pg of homologous DNA. Probes labelled with digoxigenin or 32P by RHP detected 0.1 pg of homologous DNA, and 1-10 CMV-infected fibroblasts. Comparison of digoxigenin- and 32P-labelled probes in a DNA hybridisation assay on 186 urine specimens demonstrated that these probes were of similar sensitivity, detecting CMV DNA in 40 and 41 specimens, respectively. Positive results were obtained using this hybridisation assay with 11 of 14 specimens (79%) yielding CMV by virus isolation, and with 35 other specimens obtained from patients with laboratory evidence of CMV infection or symptoms compatible with CMV disease. Thus digoxigenin-labelled probes may provide an assay that can detect CMV DNA in specimens yielding a negative result by virus isolation.