Polymerase chain reaction for the diagnosis of hepatitis B and C viral hepatitis

Outbreak of avian mycobacteriosis in a commercial turkey breeder flock

Avian mycobacteriosis (AM) is a chronic and contagious disease of pet birds, captive exotic, wild and domestic fowl, and mammals. Mycobacterium avium subsp. avium is the most common cause of AM in poultry. For the first time, we report a chronic outbreak of AM in an Iranian breeder flock of 250 45-week-old turkeys (Meleagris gallopavo) with a morbidity and mortality rate of 91.6% and 80%, respectively. A well-defined clinical feature of the outbreak included a progressive weight loss, decreased egg production, listlessness, and lameness. Tuberculous nodules were seen on liver, spleen, ovary, and ribs. Granulomatous inflammation and acid-fast bacilli were confirmed by using Ziehl-Neelsen method on hepatic lesions. M. avium subsp. avium was identified by polymerase chain reaction techniques based on the presence of 16S ribosomal RNA gene and insertion elements IS1245 and IS901. In this report, we not only describe the epidemiological, pathological, and molecular characteristics of the outbreak in detail, but we also discuss multiple factors influencing the introduction and development of AM critically. In this case, wild feral pigeons might have been the source of infection, but further molecular-epidemiology studies are needed to understand the role of wild birds in the persistence and transmission of Mycobacterium.RESEARCH HIGHLIGHTS First report of avian mycobacteriosis in an Iranian commercial turkey flock is described in detail.Risk factors intrinsic to the bird and mycobacteria, as well as extrinsic factors influencing the introduction and development of avian mycobacteriosis in birds, are critically discussed.

Detection and quantification of hepatitis B virus DNA by SYBR green real-time polymerase chain reaction

A single-round real-time polymerase chain reaction (PCR) assay based on SYBR green dye technology for the detection and quantification of hepatitis B virus (HBV) DNA in serum was evaluated and compared with a qualitative nested PCR and the Cobas Amplicor HBV Monitor assay (Roche Molecular Diagnostics, Milan, Italy). The performance of the real-time PCR assay was evaluated in a routine clinical laboratory setting with a total of 212 clinical specimens. The sensitivity of the real-time PCR corresponded to 31 IU/ml (70 copies/ml), and comparison with the qualitative nested PCR showed significant concordance for 94% of samples. The linear curve over 7 log units, spanning 10(3)-10(9) IU/ml (2.28 x 10(3) to 2.28 x 10(9) copies/ml), was observed in the quantitative determination. The interexperimental variability coefficient of the assay ranged from 0.22 to 0.39 and the intraexperimental variability coefficient from 0.24 to 0.41. By excluding values outside of the dynamic ranges of both tests, the HBV Monitor and the real-time PCR gave an agreement within +/-1 log unit for 90% of samples, while those for the remaining 10% were found to be above 1 log unit but less than 1.5 log units. When the results inside and outside the dynamic range of the HBV Monitor were examined, 90% of the results were in agreement. In conclusion, the real-time PCR based on SYBR green technology proved suitable for routine diagnostic purposes, showing good sensitivity, high specificity, high reproducibility, and good linearity over a broad dynamic range of quantification.

Cytokine profile in Egyptian hepatitis C virus genotype-4 in relation to liver disease progression

AIM: To observe the imbalance between T helper cell Th1 and Th2 cytokines in several chronic hepatitis disease at different stages of disease progression.

METHODS: We measured the cytokine levels of Th1 (IL-2 and IL-2R), Th2 (IL-10) and the pro-inflammatory cytokines (IL-6 and IL-6R and TNF and TNF-RI and II) by the ELISA technique in the sera of 33 hepatocellular carcinoma (HCC) patients and 20 chronic liver disease (CLD) patients. In addition, 20 asymptomatic hepatitis C virus carriers and 20 healthy subjects negative for hepatitis C virus(HCV) markers served as controls.

RESULTS: Anti-HCV antibodies were found to be positive in 94% of HCC cases and 75% of CLD cases. On the other hand, HCV viremia was detected using RT-PCR in 67% of HCC cases and 65% of CLD cases. HBsAg was positive in 9% of HCC cases and 30% of CLD cases. Also bilharzial-Ab was positive in 55% of HCC cases, 65% of CLD cases and in 70% of asymptomatic carriers (ASC). HCC patients had significantly higher values of IL-2R, TNF-RII (P<0.001), and TNF-RI (P>0.05), but lower TNFα (P<0.001) and IL-6 (P = 0.032) in comparison to ASC. But, in comparison to non-cancer controls, HCC patients had higher values of IL-2R, IL-6R, TNF-RI and TNF-RII, but lower TNF-α (P<0.001). CLD patients had higher IL-2R, TNF-RI, and TNF-RII (P<0.001) than ASC. But, in comparison to non-cancer controls, CLD patients had higher values of IL-2R, TNF-RI and TNF-RII, but lower TNF-α (P<0.001). IL-10 was higher (though not significantly) in HCC and CLD patients than in symptomatic carriers and non-cancer controls.

CONCLUSION: Liver disease progression from CLD to HCC due to HCV genotype-4 infection is associated with an imbalance between Th1 and Th2 cytokines. IL-2R, TNF-RI, and TNF-RII could be used as potential markers.

Real-time PCR for detection and quantitation of hepatitis B virus DNA

A sensitive and reproducible real-time PCR assay based on TaqMan technology was developed for the detection and quantitation of hepatitis B virus (HBV) DNA in serum, and compared with an "in-house" qualitative PCR assay. HBV DNA was measured in 125 serum samples from 76 hepatitis B patients, consisting of 22 patients with an acute infection, 20 patients with a previous history of hepatitis B infection, and 34 patients with a chronic hepatitis B. Four patients with a chronic infection were treated with either an IFN-alpha monotherapy or a combination of IFN-alpha and lamivudine. Twenty-nine sera from healthy individuals and non-hepatitis B patients served as negative controls. The assay was validated by using a 10-fold dilution series of the World Virological Quality Control (VQC) sample containing 3.73 x 10(7) genome equivalents per ml. The detection limit for the real-time PCR was 3.73 x 10(2) genome equivalents per ml (geq/ml), while it was 3.73 x 10(3) geq/ml for the in-house PCR. The real-time PCR assay had an 8-logarithm dynamic range spanning from 10(2) to 10(10) geq/ml. In clinical serum samples, the real-time PCR and the in-house PCR detected HBV DNA in 81% (101/125) and 66% (83/125) of samples, respectively. HBV DNA was not detected among the negative controls by either of these assays. In conclusion, real-time PCR is a sensitive, specific, and a reproducible approach for the detection and quantitation of HBV DNA in clinical serum samples, useful also for monitoring the efficacy of antiviral treatment.

Hepatitis C

In the latter half of the 20th century, HCV emerged as the most common cause of chronic liver disease, and will likely remain so. Since its initial discovery in 1989, rapid progress has been made in our understanding of the virology, epidemiology, natural history, diagnosis, and treatment of HCV. Over the next few decades, as further advancements are made, superior treatment options will become available.

Leishmania braziliensis: characterisation of a complex specific subtelomeric repeat sequence and its use in the detection of parasites

A 1.6-kb tandem repeat sequence had previously been identified in the subtelomeric region of mini- and megabase chromosomes from Leishmania braziliensis. Southern hybridisation was used to demonstrate that the repeat is complex specific. The sequence was characterised in strains representing four species of the L. braziliensis complex. This data allowed an assessment of the evolutionary relationship of the four species. PCR primers targeted to the repeat amplify only DNA from species of the L. braziliensis complex. Titration assays indicate that a minimum of 50 fg of parasite DNA can be detected by PCR alone. Southern hybridisation increases the limit of detection to 5 fg. Interspecies variation in the repeat sequence enabled restriction enzyme digestion of PCR products to distinguish individual species within the L. braziliensis complex.

Trypanosoma cruzi: specific detection of parasites by PCR in infected humans and vectors using a set of primers (BP1/BP2) targeted to a nuclear DNA sequence

In the present work we evaluate Trypanosoma cruzi DNA detection by PCR using the nuclear oligonucleotides BP1/BP2 as primers. These primers are targeted to the 5' and 3' ends of the coding region for the flagellar protein F29. An amplification product of BP1/BP2 is a DNA band 692 bp long. Titration assays were performed to evaluate the minimum amount of parasite DNA that can be detected by this assay, resulting in 10 fg (equivalent to about 1/20 of the genome). The assay was also performed using T. cruzi DNA from different strains, clones, and human-derived isolates obtaining, in all cases, amplification products. No DNA amplification was observed when the PCR was performed using DNA from Leishmania braziliensis, but when T. rangeli DNA was used, a 615-bp-long fragment was amplified. Under appropriate gel conditions T. cruzi and T. rangeli DNA amplicons could be differentiated. When both conventional xenodiagnosis and PCR detection of parasite DNA in the feces of insect vectors fed with blood from infected patients were compared, 10 of 20 samples were positive by both techniques. However, 2 other samples with positive serology were also positive by PCR. When PCR was performed on blood samples from infected and uninfected individuals, 62 of 65 serologically positive human samples amplified the BP1/BP2 692-bp T. cruzi DNA fragment (sensitivity >95%). The 3 negative samples were positive when Southern blot hybridization was performed using the radiolabeled PCR amplification product as probe (sensitivity 100%).

Hepatitis C virus seroconversion by a third generation ELISA screening test in blood donors

The significance of seroconversion as detected by an ELISA screening test for hepatitis C virus (HCV) antibody with a negative supplemental/confirmatory recombinant immunoblot assay (RIBA) result was investigated. Of 118,220 established West Midlands blood donors with at least one negative HCV antibody screen, 43 had seroconverted in 1994 according to the ELISA but had negative RIBA-3 results. The paired archive serum samples of the pre- and postseroconversion donations of 29 seroconverting donors were tested by nested polymerase chain reaction (PCR) for the detection of HCV RNA. All 58 samples were negative by PCR. The absence of detectable viraemia in all tested seroconverting donors suggests that HCV infection was not responsible for seroconversion by ELISA.

Microbiological and serological investigations of oral lesions in Papillon-Lefèvre syndrome

Microbiological and serological (enzyme linked immunosorbent assay) investigations were carried out, including karyotyping, on two Asian children with Papillon-Lefèvre syndrome. In case 1, a girl aged four years, the most prevalent putative periodontopathogens were Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia (deciduous dentition) and Bacteroides gracilis, E corrodens and F nucleatum (permanent dentition). In case 2, a boy aged nine years, they were F nucleatum, P intermedia and P loeschii and E corrodens. Serum from case 2 showed a raised specific IgG antibody response to Actinomyces actino-mycetemcomitans serotype b. Thus, a wider range of species than hitherto reported may be associated with Papillon-Lefèvre syndrome, including A actino-mycetemcomitans and F nucleatum.

Clinical evaluation of a single reaction, diagnostic polymerase chain reaction assay for the detection of hepatitis C virus RNA

BACKGROUND/AIMS

In the past few years the detection of HCV-RNA by polymerase chain reaction has become a well-established diagnostic tool for patients with chronic hepatitis C. However, the lack of reproducible results between laboratories and the relatively high proportion of false-positive results, has indicated the need for a standardized and reliable polymerase chain reaction assay. In the present study we have analyzed the performance of a commercial, HCV-RNA polymerase chain reaction assay based on a single, combined reverse transcription and amplification reaction and on the use of Uracil-N-glycosilase to prevent carry-over contamination (Amplicor HCV, Roche Molecular Systems).

METHODS

In this assay the amplification products are detected in microwell plates using biotinylated primer and the HRP avidin colorimetric system. Serum samples collected from 446 patients, including 181 with chronic active hepatitis C, 50 with autoimmune chronic hepatitis, 117 in hemodialysis, 30 asymptomatic carriers of anti-HCV and 68 with indeterminate serology (RIBA indeterminate results), as well as from 121 controls were tested with the commercial, single-step assay and with nested polymerase chain reaction. Both techniques use primers located within the 5' non-coding region of the HCV genome.

RESULTS

In all cases a good concordance was observed between the commercial, single-step assay and nested polymerase chain reaction which, for patients with chronic active hepatitis, showed a sensitivity and specificity of 100% and 99.3% for the former and of 98.8% and 100% for the latter, when compared to clinical diagnosis taken as the gold standard. Most of the 11 discordant samples were seen in the group of RIBA-indeterminate cases and in patients with chronic active hepatitis C. Further analysis of these cases, based on repeat testing and clinical data showed that 64% and 36% of the discrepancies were due, respectively, to nested polymerase chain reaction and Amplicor inconsistent reactions. In hemodialyzed patients, patients with autoimmune hepatitis and asymptomatic carriers of anti-HCV, both assays produced results which were consistent with the clinical diagnosis. In the former group, polymerase chain reaction was able to identify the presence of active viral replication in some antibody negative samples.

CONCLUSIONS

Taken together, these results indicate that the commercial, single-step polymerase chain reaction assay has the same clinical sensitivity and specificity as nested polymerase chain reaction and that, because of its simplified procedures and fast turn-around time, it may be a valuable test for routine diagnostic applications.

PCR analysis of hepatitis B virus DNA in paraffin-embedded liver tissue from patients with chronic liver disease

We described a nested polymerase chain reaction protocol to detect hepatitis B viral DNA in paraffin-embedded liver tissue and tried to determine whether this virus was associated with non-B chronic liver disease. Fifty-five samples were obtained from 28 patients with B, and 27 patients with non-B chronic liver disease (35 cirrhosis, 4 hepatocellular carcinoma and 16 chronic hepatitis). The two sets of primers amplify a sequence located in a conserved polymerase/surface region of the viral genome. Reaction products were analysed using a nonisotopic hybridization method. None of the 27 (0%) seronegative samples and 20 of the 28 (71%) seropositive specimens were positive for hepatitis B virus DNA. There were 4 false negatives in which beta-globin PCR was positive. Although its sensitivity is reduced in formalin-fixed paraffin-embedded tissue, nested PCR allows rapid detection of HBV DNA sequences and can be a useful tool if no frozen tissue is available.

Hepatitis C virus seroconversion rate in established blood donors

The results of hepatitis C virus (HCV) antibody test of 237,813 blood donations collected from 143,815 donors by the West Midlands Blood Transfusion Centre in 1993 were analyzed retrospectively in order to determine the seroconversion rate among established previously anti-HCV negative donors. Three hundred sixteen (0.22%; 1 in 455) donors were positive by the enzyme linked immunosorbent assay (ELISA) screening test and 34 (0.024%; 1 in 4,230) donors were positive by ELISA and the Recombinant Immuno Blot Assay (RIBA). Three donors previously negative for HCV antibody reacted positively by both tests. The annual seroconversion rate was calculated as one in 35,937 donors. This figure argues against limitation of HCV antibody screening to new blood donors. A further 45 donors negative on previous screening reacted positively by ELISA and were indeterminate by RIBA. Unexpectedly, lapsed blood donors first tested for HCV antibody in 1993 had high positive reaction rates by ELISA and RIBA, which was significantly (P < 0.001) higher than those of new donors. RIBA-positive reaction rate among ELISA-positive donors was significantly higher amongst males than females (P < 0.001).

High rate of mixed genotypes of hepatitis C virus in patients of an epidemic area in Japan

The subjects of this study were 151 patients (69 males and 82 females) who underwent examination and liver biopsy owing to liver dysfunction in an epidemic area with hepatitis C. Second generation hepatitis C virus antibody (HCV Ab) was positive in 116 (76.8%) of 151 cases. HCV-RNA was detected in 120 (79.5%) by polymerase chain reaction (PCR). In 7 (4.6%) cases, HCV Ab could not be found, but HCV-RNA was detected. Three (2.0%) cases were positive for HCV Ab but negative for HCV-RNA. On the basis of variation in nucleotide sequence within a restricted region in the putative core gene of HCV, HCV genotypes were classed into four types of I, II, III and IV by PCR. The genotypes were identified in 120 cases. Ninety-eight (81.7%) cases carried one of the four types. Type II was found in 76 (63.3%) cases and type III in 22 (18.3%). The other 22 (18.3%) carried simultaneously two different genotypes (mixed type): 21 (17.5%) cases with type II + III and one (0.8%) case with type II + IV. In comparison with the incidence of HCV mixed types in cases with hepatitis C in a non-epidemic area, carriers of mixed types were found at a significantly higher rate in the epidemic area. Liver biopsy of 120 cases with identified HCV genotypes in the epidemic area showed 93 cases of chronic active hepatitis, nine of chronic lobular hepatitis, 10 of chronic persistent hepatitis and eight of liver cirrhosis. No significant correlation could be detected between liver histology and HCV genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitation of HCV-replication using one-step competitive reverse transcription-polymerase chain reaction and a solid phase, colorimetric detection method

A solid phase assay for the colorimetric detection of competitively amplified HCV-cDNA has been established and used to investigate clinical samples from patients with chronic hepatitis. The assay is based on the reduction in the amplification of an hepatitis C virus-related competitor molecule by wild-type hepatitis C virus during polymerase chain reaction. The internal standard contains a lac operator sequence, allowing the amount of amplified competitor to be determined using a lac I-repressor/beta-galactosidase fusion protein. The reduction in the amplification of competitor is dependent upon the concentration of HCV-RNA in the original sample. External hepatitis C virus wild-type standards are used to calibrate each concurrently tested set of patients. We present and discuss the potential benefit, but also the limitations of this new approach for quantifying hepatitis C virus viremia. In 47 serum samples from 28 patients with chronic hepatitis C virus infection, including five repeatedly tested alpha HCV positive patients under interferon therapy, viral titer was determined. Sera from nine healthy blood donors served as controls. The sensitivity and specificity of this procedure are identical to those of conventional nested polymerase chain reaction. As both internal and external standards are used in every assay and final detection of amplicons can be carried out in microtiter plates, this reliable and time-saving test system may be routinely applied for monitoring antiviral treatment or for studying the relation of plus- and minus-stranded HCV-RNA in infected tissues.