Circulating human papillomavirus DNA detection in Barrett's dysplasia and esophageal adenocarcinoma.

There is evidence to suggest that human papillomaviruses (HPV) are associated with Barrett's dysplasia and esophageal adenocarcinoma. In other HPV-linked cancers such as cervical and oropharyngeal cancer, circulating HPV DNA is a potential biomarker to assist in tumor diagnosis and management. This study aimed to determine whether circulating HPV DNA was detectable in patients with Barrett's dysplasia and esophageal adenocarcinoma, and if so, whether there is any correlation with esophageal tissue HPV status. Plasma from 138 patients representing esophageal adenocarcinoma (N = 41), Barrett's dysplasia (N = 48) and hospital controls (N = 49) were analyzed for the presence of circulating HPV DNA using droplet-digital PCR targeting the E7 gene of HPV types 16 and 18. Circulating HPV DNA was detected in 11/138 (8.0%) study subjects including 1/49 (2.0%) hospital controls, 4/48 (8.3%) Barrett's dysplasia patients, and 6/41 (14.6%) esophageal adenocarcinoma patients. Detection of circulating HPV DNA was higher in patients with HPV-positive esophageal tissue (6/35, 17.1%) compared to those with HPV-negative specimens (5/103; 4.9%) (OR = 4.06; 95% CI 1.15-14.25; P = 0.020). The highest rates of detection occurred in esophageal adenocarcinoma patients, particularly those with invasive tumors that had breached the esophageal submucosa, had regional lymph node involvement or metastatic disease. Circulating HPV DNA was detectable in a subset of Barrett's dysplasia and esophageal adenocarcinoma patients. Detection was associated with tissue HPV positivity and possibly disease severity.

Clinical aspects of cytomegalovirus antiviral resistance in solid organ transplant recipients.

Despite advances in the prophylaxis and acute treatment of cytomegalovirus (CMV), it remains an important pathogen affecting the short- and long-term clinical outcome of solid organ transplant. The emergence of CMV resistance in a patient reduces the clinical efficacy of antiviral therapy, complicates therapeutic and clinical management decisions, and in some cases results in loss of the allograft and/or death of the patient. There is increasing use of antiviral prophylaxis after transplant with little expansion in the range of antiviral agents effective in treatment of CMV. Further understanding is needed of the risk factors for development of CMV antiviral resistance and of therapeutic strategies for treating patients infected with resistant viruses. We review the current status of CMV resistance in solid organ transplant recipients, and provide diagnostic and therapeutic suggestions for the clinician in managing antiviral resistance.

Organ donor screening using parallel nucleic acid testing allows assessment of transmission risk and assay results in real time.

Expansion of the donor pool may lead to utilization of donors with risk factors for viral infections. Donor laboratory screening relies on serological and nucleic acid testing (NAT). The increased sensitivity of NAT in low prevalence populations may result in false-positive results (FPR) and may cause unnecessary discard of organs.We developed a screening algorithm to deal, in real time, with potential FPR. Three NAT assays: COBAS AmpliScreen assay (CAS), AmpliPrep Total Nucleic Acid Isolation/CAS, and AmpliPrep/TaqMan assays, were validated and used in parallel for prospective screening of increased-risk donors (IRD), and the probability of FPR was calculated. The lower limit of detection of this algorithm was 9.79, 21.02, and 4.31 IU/mL for human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus, respectively, with an average turn-around-time of 7.67 h from sample receipt to result reporting. The probability that a donor is potentially infectious with two NAT concordant results was >90%. NAT screening of 35 IRD within 18 months resulted in transplantation of 102 additional organs that without screening would either not be used or used with restrictions in Australia. Using a parallel testing algorithm, real-time confirmation of seropositive donors allows use of organs from IRD and safer expansion of the donor pool.

Early IL-10 predominant responses are associated with progression to chronic hepatitis C virus infection in injecting drug users.

The critical events in clearance or persistence of hepatitis C virus (HCV) infection are unknown but likely to be determined early in acute infection. Type 1 and type 2 cytokine production was assessed by HCV peptide ELISpot and multiplex in vitro cytokine production assays in longitudinally collected samples from 20 untreated participants enrolled in the Australian Trial in Acute Hepatitis C (ATAHC); a prospective cohort of acute HCV infection (77% injecting drug users, IDU). Significantly higher interleukin-10 (IL-10) production (P = 0.048), in the relative absence of interferon-gamma (IFN-γ) and IL-2 production, was present early in HCV infection in those who progressed to chronic infection. In contrast, viral clearance was associated with a greater magnitude and broader specificity of IFN-γ (magnitude P < 0.001, breadth P = 0.004) and IL-2 responses, in the relative absence of IL-10. Early IL-10 production was correlated with higher HCV RNA level at baseline (P = 0.046) and week 12 (P = 0.018), while IFN-γ and IL-2 production was inversely correlated with HCV RNA level at baseline (IFN-γ P = 0.020, IL-2 P = 0.050) and week 48 (IFN-γ P = 0.045, IL-2 P = 0.026). Intracellular staining (ICS) indicated the HCV-specific IFN-γ response was primarily from CD8(+) T cells and NK cells, whereas IL-10 production was predominantly from monocytes, with a subset of IL-10 producing CD8(+) T cells present only in those who progressed to chronic infection. IL-10, an immunoregulatory cytokine, appears to play a key role in progression to chronic HCV infection.

Mycoplasma genitalium is associated with cervicitis and HIV infection in an urban Australian STI clinic population.

OBJECTIVES: To investigate the prevalence of the genital mollicutes, Mycoplasma genitalium (MG), Mycoplasma hominis (MH), Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP), and their associations with cervicitis in a sexually transmitted infection (STI) clinic population. Clinical correlates of MG infection were also assessed. METHODS: 527 women were enrolled in a cross-sectional study at two STI clinics in Sydney between June 2006 and January 2010. Genital mollicutes were detected by multiplex PCR testing of cervical swabs, and associations with cervicitis were analysed. Cervicitis was defined as >30 polymorphonuclear cells per high-power field in at least three non-adjacent fields of cervical mucus on Gram stain. RESULTS: MG was found in 4.0% of women, MH in 17.1%, UU in 14.1%, and UP in 51.8%. MG was the only mollicute associated with cervicitis (unadjusted prevalence ratio (PR) 1.85, 95% CI 1.52 to 2.26, p<0.0001), and this association remained after adjustment for Chlamydia trachomatis (CT) infection (adjusted PR 1.24 (95% CI 1.04 to 1.48), p=0.02). MG was significantly associated with women being HIV positive (p=0.03), but not with age, vaginal discharge, commercial sex work, being of culturally and linguistically diverse background, or concurrent CT infection. Two of the 21 women with MG had ectopic pregnancies. CONCLUSIONS: The authors recommend wider application of PCR testing for MG in STI services, particularly in high-risk women and those with cervicitis or HIV infection.

Diversity of antiviral-resistant human cytomegalovirus in heart and lung transplant recipients.

Immunocompromised transplant recipients are at high risk for human cytomegalovirus (CMV)-related infection and disease. Antiviral prophylaxis and treatment have reduced CMV morbidity and mortality, but at times promote development of antiviral-resistant CMV strains that can significantly contribute to adverse clinical outcomes in transplant recipients. We have investigated CMV genotypes in transplant recipients (bone marrow, stem cell, kidney, heart, lung, and liver) receiving antiviral prophylaxis or preemptive therapy or treatment, to determine the viral characteristics and clinical impact of antiviral-resistant CMV in these different groups. Antiviral-resistant CMV strains were detected by polymerase chain reaction sequencing of the CMV protein kinase (UL97) and viral DNA polymerase (UL54) genes from clinical specimens. A trend toward more frequent detection of multidrug resistance and co-circulation of multiple resistant strains was seen in heart and lung transplant recipients compared with other transplantation types. A greater diversity and number of UL97 and UL54 mutations were observed in heart and lung transplant recipients; whereas antiviral-resistant CMV infections in other transplant recipients were predominantly the result of a single mutant genotype. Furthermore, 43% (6/14) of CMV-positive heart and lung transplant recipients were infected with CMV strains containing UL54 mutations conferring multidrug resistance compared with only 6% (1/18) of CMV-positive recipients of other transplanted organs or stem cells. Emergence of CMV strains containing previously unrecognized UL54 mutations (F412S and D485N) also occurred in 1 lung and 1 heart transplant recipient. The development of these mutations under antiviral selective pressure, and clinical outcome of infection suggests these mutations are likely to confer antiviral resistance. Emergence of CMV antiviral resistance remains a significant issue in immunocompromised patients treated with antiviral agents, and emphasizes the relevance of regular antiviral resistance testing when designing optimal patient-management strategies.

Viruses and other infections in stillbirth: what is the evidence and what should we be doing?

In Australia, as in other developed countries, approximately 40-50% of stillbirths are of unknown aetiology. Emerging evidence suggests stillbirths are often multifactorial. The absence of a known cause leads to uncertainty regarding the risk of recurrence, which can cause extreme anguish for parents that may manifest as guilt, anger or bewilderment. Further, clinical endeavours to prevent recurrences in future pregnancies are impaired by lack of a defined aetiology. Therefore, efforts to provide an aetiological diagnosis of stillbirth impact upon all aspects of care of the mother, and inform many parts of clinical decision making. Despite the magnitude of the problem, that is 7 stillbirths per 1000 births in Australia, diagnostic efforts to discover viral aetiologies are often minimal. Viruses and other difficult to culture organisms have been postulated as the aetiology of a number of obstetric and paediatric conditions of unknown cause, including stillbirth. Reasons forwarded for testing stillbirth cases for infectious agents are non-medical factors, including addressing all parents' need for diagnostic closure, identifying infectious agents as a sporadic cause of stillbirth to reassure parents and clinicians regarding risk for future pregnancies, and to reduce unnecessary testing. It is clear that viral agents including rubella, human cytomegalovirus (CMV), parvovirus B19, herpes simplex virus (HSV), lymphocytic choriomeningitis virus (LCMV), and varicella zoster virus (VZV) may cause intrauterine deaths. Evidence for many other agents is that minimal or asymptomatic infections also occur, so improved markers of adverse outcomes are needed. The role of other viruses and difficult-to-culture organisms in stillbirth is uncertain, and needs more research. However, testing stillborn babies for some viral agents remains a useful adjunct to histopathological and other examinations at autopsy. Modern molecular techniques such as multiplex PCR, allow searches for multiple agents. Now that such testing is available, it is important to assess the clinical usefulness of such testing.

Presence of mouse mammary tumour-like virus gene sequences may be associated with morphology of specific human breast cancer.

BACKGROUND: Mouse mammary tumour virus (MMTV) has a proven role in breast carcinogenesis in wild mice and genetically susceptible in-bred mice. MMTV-like env gene sequences, which indicate the presence of a replication-competent MMTV-like virus, have been identified in some human breast cancers, but rarely in normal breast tissues. However, no evidence for a causal role of an MMTV-like virus in human breast cancer has emerged, although there are precedents for associations between specific histological characteristics of human cancers and the presence of oncogenic viruses. AIM: To investigate the possibility of an association between breast cancer and MMTV-like viruses. METHODS: Histological characteristics of invasive ductal human breast cancer specimens were compared with archival MMTV-associated mammary tumours from C3H experimental mice. The presence of MMTV-like env DNA sequences in the human breast cancer specimens was determined by polymerase chain reaction and confirmed by Southern hybridisation. RESULTS: MMTV-like env gene sequences were identified in 22 of 59 (37.3%) human breast cancer specimens. Seventeen of 43 (39.5%) invasive ductal carcinoma breast cancer specimens and 4 of 16 (25%) ductal carcinoma in situ specimens had some histological characteristics, which were similar to MMTV-associated mouse mammary tumours. However, these similarities were not associated with the presence or absence of MMTV-like gene sequences in the human breast tumour specimens. A significant (p = 0.05) correlation was found between the grade of the human breast cancer and similarity to the mouse mammary tumours. The lower the grade, the greater the similarity. CONCLUSION: Some human breast cancer specimens, in which MMTV-like env DNA sequences have been identified, were shown to have histological characteristics (morphology) similar to MMTV-associated mouse mammary tumours. These observations are compatible with, but not conclusive of, an association between the presence of MMTV-like env DNA sequences and some human breast cancers.

Mapping dispersed repetitive loci using semi-specific PCR cloning and somatic cell hybrid mapping.

A simple and effective method based upon semi-specific PCR followed by cloning has been developed. Chromosomal mapping of the generated fragment on a somatic cell hybrid panel identifies the chromosomal position, and yields a unique sequence tag for the site. Using this method, the chromosomal location of one porcine endogenous retrovirus (PERV) was determined. The porcine genomic sequences were first amplified by PCR using a PERV-specific primer and a porcine short interspersed nuclear element (SINE)-specific primer. PCR products were cloned, and those sequences that contained PERV plus flanking regions were selected using a second round of PCR and cloning. Sequences flanking the PERV were determined and a PERV-B was physically mapped on porcine chromosome 17 using a somatic hybrid panel. The general utility of the method was subsequently demonstrated by locating PERVs in the genome of PERV infected human 293 cells. This method obviates the need for individual library construction or linker/adaptor ligation, and can be used to quickly locate individual sites of moderately repeated, dispersed DNA sequences in any genome.

Virological diagnosis of Ebolavirus infection.

Ebolaviruses, and the other viral causes of haemorrhagic fevers (VHF) have always posed special problems for diagnostic laboratories. These arise from the rarity of human infections, minimal documented experience with test delivery and interpretation, the paucity of established commercial or in-house assays, the lack of clinical material for test development and validation, the high level containment required for handling live virus, the ongoing evolution of the viruses, and the high personal and public health requirements for accurate diagnosis. This article addresses the current situation and the ongoing challenges associated with delivering timely, high quality and safe testing within Australia for people exposed as part of the current major outbreak of Ebolavirus disease (EVD) in Western Africa. The members of the Public Health Laboratory Network have developed deliverable and reliable nucleic acid detection tests, and also have the laboratory capacity to handle the live viruses if necessary. However delivering and maintaining these services necessitates high levels of experience in developing and applying tests for exotic and emerging infections, strong national and international links and collaborations, ongoing monitoring and reassessment of test design and performance, innovative approaches to generation of positive control material, and a regular quality assurance program.

Ex vivo model of congenital cytomegalovirus infection and new combination therapies.

INTRODUCTION: Congenital human cytomegalovirus (HCMV) infection is a major public health problem due to severe sequelae in the fetus and newborns. Currently, due to their toxicity anti-CMV treatments cannot be administered to pregnant women. We thus developed an ex vivo model of 1(st) trimester placental CMV infection to observe the route of infection across the placenta and to test the efficacy of various new drugs targeting different stages of viral cycle. METHODS: After validation of the viability of floating villi explants by ELISA ß-HCG, the kinetics of placental infection were determined by immunochemistry and qPCR in this ex vivo model. Antiviral susceptibility was determined in vitro using focus reduction assay and by qPCR in the ex vivo model. RESULTS: The ex vivo model showed viral infection in trophoblasts and mesenchymal space of floating villi. In vitro, antiviral combinations of maribavir with baïcalein or artesunate inhibited viral infection by more than 90%. On the other hand, in ex vivo model, infection was reduced by 40% in presence of maribavir and artesunate. The synergistic effect observed in vitro was not observed ex vivo. DISCUSSION: This model allowed us to understand the CMV spread in 1(st) trimester floating villi better and to analyze the anti-CMV efficacy and toxicity of new drugs that could be administered to pregnant women, either alone or in combination. CONCLUSIONS: Such an ex vivo model could be applied to other viruses such as rubella or parvovirus B19 and in new drug development.

Transmission of porcine endogenous retroviruses in severe combined immunodeficient mice xenotransplanted with fetal porcine pancreatic cells.

BACKGROUND: Xenotransplantation using pig organs or tissues may alleviate the human donor organ shortage. However, one concern is the potential transmission of pig pathogens to humans, especially pig endogenous retroviruses (PERV), which infect human cell lines in vitro. In this report, the cross-species in vivo transmission of PERV by xenotransplantation was studied using a severe combined immunodeficient (SCID) mouse model. METHODS: Twenty-one SCID mice were transplanted with fetal pig pancreatic cells and left for periods from three to 41 weeks before being killed. DNA and RNA were extracted from liver, spleen, and brain of these mice, and examined for PERV using nested polymerase chain reaction (PCR) and reverse transcriptase-PCR. The pig mitochondrial cytochrome oxidase II subunit gene (COII) was also amplified to monitor the presence of pig cell microchimerism in xenotransplanted tissues, and a housekeeping gene was included to monitor the DNA quality and quantity. RESULTS: Examination of 39 DNA samples from tissues of the 21 xenografted mice identified two mouse tissues (M4-liver and M19-spleen) that were positive for PERV but negative for COII. A total of 23 (59%) of the mouse tissues were positive for both PERV and COII, 6 (16%) were negative for both, and 8 (20%) were positive for COII only. PCR and direct sequencing of the PCR products identified three PERV variants, which were different from the PERV sequence detected by PCR direct sequencing from the pig donor cells. CONCLUSIONS: The PERV+/COII- results from M4-liver and M19-spleen indicated the presence of PERV transmission from pig to mouse tissue. The PERV variants detected in the mouse tissues indicated that different PERVs were transmissible from the pig to mouse tissue during xenotransplantation. The negative reverse transcriptase-PCR results for PERV from three mouse samples including M4-liver and M19-spleen suggest there was no active PERV transcription in the mouse tissues, although this would need to be studied further.

Simian T cell leukemia virus type I from naturally infected feral monkeys from central and west Africa encodes a 91-amino acid p12 (ORF-I) protein as opposed to a 99-amino acid protein encoded by HTLV type I from humans.

A single protein of 12 kDa, p12 is encoded by the HTLV-I genome from both the singly spliced mRNA pX-ORF-I and doubly spliced mRNA pX-rex-ORF-I. While many full-length sequences of HTLV-1 are known, data on the p12 regions of African STLV-I are unavailable. We have undertaken to sequence the p12 gene in STLV-I from Central and West Africa naturally infected primates, and have compared them to known p12 sequences of HTLV-I. Our data on sequence and in vitro transcription-translation analyses indicate that p12 is a 91-amino acid (aa) protein among STLV-I strains from Central and West Africa, in contrast to the 99-aa protein found among HTLV-I strains around the globe. The p12 sequences of STLV-I exhibit a marked genetic variability at the level of both nucleotide and peptide sequences. Hydropathic and helical wheel analyses reveal that 60% of residues in HTLV-I p12 are hydrophobic, in contrast to 55% in STLV-I from Africa. Although HTLV-I and STLV-I show a similar putative antigenic site, a second potential site was located exclusively in STLV-I from Africa. There are differences in the predicted transmembrane domains in p12 between STLV-I and HTLV-I. Furthermore, the secondary structure data according to the Chou and Fasman algorithm predict an alpha-helical domain at the carboxy terminus in HTLV-I, and this domain may be truncated in STLV-I p12. The amino acid sequence of p12 shows two leucine zipper motifs (LZMs) at the amino terminus and in the middle region, respectively. This is the first report describing the size differences in p12 protein between HTLV-I and STLV-I, which may provide insights into pathogenic mechanisms used by HTLV-I and STLV-I.

Characterisation of two new gene cassettes, aadA5 and dfrA17.

Escherichia coli INS33 was isolated from the urinary tract of an infected patient. It was resistant to ampicillin, chloramphenicol, spectinomycin, streptomycin, sulfafurazole, tetracycline and trimethoprim. PCR screening revealed the presence of a class 1 integron that harboured two new gene cassettes, designated dfrA17 and aadA5. The new dfrA17 cassette was 91% identical to the known dfrA7 cassette. The aadA5 cassette was 95% identical over the first 830 bp to aadA4, but lacked the IS26 element found at the 3' end of this truncated cassette. Cloning and expression of the cassette region demonstrated that dfrA17 conferred high level resistance to trimethoprim but aadA5 conferred resistance to spectinomycin but not to streptomycin.

Sequence diversity in the 5'-UTR region of GB virus C/hepatitis G virus assessed using sequencing, heteroduplex mobility analysis and single-strand conformation polymorphism.

GB virus C/hepatitis G virus (GBV-C/HGV) is a positive-sense RNA virus belonging to the Flaviviridae family identified recently. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect GBV-C/HGV RNA using nested primers designed to amplify 245 bp of the 5'-untranslated region (UTR). GBV-C/HGV RNA was detected in 20.7% of 101 HCV-RNA positive and 6.8% of 44 HCV-RNA negative specimens. Sequencing of the PCR products demonstrated they had between 84.3 and 100% nucleotide identity. Most of the diversity corresponded to two variable regions identified within the 5'-UTR. Phylogenetic analysis indicated that GBV-C/HGV subtypes present in Australia belonged to group 2 and were closest in evolutionary terms to isolates from the USA and Europe. All isolates were analysed using single-strand conformation polymorphism (SSCP) and heteroduplex mobility analysis (HMA) on 8% non-denaturing polyacrylamide gels. SSCP of the isolates identified a number of distinct conformation polymorphisms that corresponded with sequence-determined genetic diversity. HMA was developed to assess the amount of genetic diversity between isolates without the need for sequencing. The average difference between the predicted divergence of two isolates calculated from the mobility of the heteroduplex and the actual value (based on nucleotide sequence) was 2.3% in this sample of isolates, where the mean sequence divergence was 8.52%.

The use of flow cytometry to detect antiviral resistance in human cytomegalovirus.

A method for detecting the antiviral susceptibility of human cytomegalovirus (HCMV) isolates to antiviral agents using flow cytometry was developed. This method has been used to detect the resistance phenotype of HCMV isolates to ganciclovir (GCV). The procedure involves infecting MRC-5 cells with 10(4) pfu HCMV for 120 h, then fixing and permeabilising the cells to allow intracellular labelling of the HCMV early and late antigens. The percentage reduction in the fluorescence positive population of HCMV-infected MRC-5 cells treated with GCV at concentrations of 20 or 50 microM compared with control cultures without GCV was determined. The IC50 defined as a < 50% reduction in the fluorescence positive population in cells infected in the presence of 20 microM GCV or an IC90 defined as a < 90% reduction in the fluorescence-positive population in cells infected in the presence of 50 microM GCV, correlated with resistance determined by a plaque reduction assay. The FACS assay is a rapid and reproducible method for detecting antiviral resistance of HCMV.

Removal of inhibitors of CSF-PCR to improve diagnosis of herpesviral encephalitis.

CSF-PCR is currently the most sensitive test to diagnose encephalitis due to cytomegalovirus or herpes simplex virus. However, false negative results sometimes arise due to inhibitors in CSF. We have shown that the inhibitory effects may be due to increased levels of proteins and increased cell numbers, but are not due to cellular DNA. Simple techniques were used to remove the inhibitors and successfully apply these methods to CSF specimens that gave equivocal results when tested untreated.

Rapid diagnosis of varicella-zoster virus infection with a monoclonal antibody based direct immunofluorescence technique.

Diagnosis of varicella-zoster virus (VZV) infection in immunocompromised patients is difficult because of the frequent atypical appearance. Accurate and early diagnosis is important to allow rapid commencement of antiviral chemotherapy, with consequent improvement in antiviral efficacy. A monoclonal based direct immunofluorescence antibody technique (VZV IFA) was assessed in parallel with viral culture in 56 patients with suspected VZV infection. A subgroup of 17 patients from this group with classical dermatomal herpes zoster all had positive VZV IFA tests. Only 6 patients (35%) were positive on viral culture. None of the 15 patients with proven herpes simplex virus infection had a positive VZV IFA, nor did any patient with positive VZV viral culture have a negative VZV IFA. The VZV IFA test is a rapid and sensitive technique for detecting infection with VZV.

Detection of astrovirus gastroenteritis in children.

A commercial enzyme immunoassay (EIA) for the detection of astrovirus antigen was used to detect the virus during a 12-month survey of enteric pathogens in children in outpatient (n = 238) and hospital (n = 176) settings. It was found to have a 100% sensitivity and 98.6% specificity. Nineteen astrovirus isolates were detected and confirmed by northern hybridization, cell culture, and RT-PCR. The virus was detected mainly amongst outpatients although a comparison of the detection rate with that in hospitalised children did not demonstrate a statistically significant difference (p = 0.1347). In contrast, there was a strong association between hospitalization and rotavirus infection (p = 0.0371), and a strong association between infection detected in outpatients and adenovirus infection (p = 0.0193). Strains of astrovirus were sequenced, genotyped and shown to be: type 1 (n = 11), type 3 (n = 1), and type 4 (n = 7). Maximum genetic variation in type 1 isolates was 8.6% and type 4 was 7.8%. Changes did not result in amino acid substitutions.

Cross-reactivity of Mycobacterium leprae and M. tuberculosis and the implications for assessment of in vitro T cell function in leprosy patients.

The cross-reactivity in vitro between Mycobacterium leprae and M. tuberculosis was studied in 41 Aboriginal Australians with leprosy, 78 uninfected contacts of leprosy patients and 38 control individuals. A vigorous T cell response to epitopes cross-reactive between these two mycobacteria was found for healthy uninfected contacts or non-contacts (controls) of leprosy patients, but not for the patients themselves. The data suggest that a vaccine based on antigen shared between M. leprae and other mycobacteria is unlikely to be useful in preventing leprosy. Further studies of responses in vitro to purified T cell-reactive antigens would be useful in designing newer vaccines for more widespread field studies of leprosy prevention.