Albert Heim

Evidence of Molecular Evolution Driven by Recombination Events Influencing Tropism in a Novel Human Adenovirus that Causes Epidemic Keratoconjunctivitis

In 2005, a human adenovirus strain (formerly known as HAdV-D22/H8 but renamed here HAdV-D53) was isolated from an outbreak of epidemic keratoconjunctititis (EKC), a disease that is usually caused by HAdV-D8, -D19, or -D37, not HAdV-D22. To date, a complete change of tropism compared to the prototype has never been observed, although apparent recombinant strains of other viruses from species Human adenovirus D (HAdV-D) have been described. The complete genome of HAdV-D53 was sequenced to elucidate recombination events that lead to the emergence of a viable and highly virulent virus with a modified tropism. Bioinformatic and phylogenetic analyses of this genome demonstrate that this adenovirus is a recombinant of HAdV-D8 (including the fiber gene encoding the primary cellular receptor binding site), HAdV-D22, (the ε determinant of the hexon gene), HAdV-D37 (including the penton base gene encoding the secondary cellular receptor binding site), and at least one unknown or unsequenced HAdV-D strain. Bootscanning analysis of the complete genomic sequence of this novel adenovirus, which we have re-named HAdV-D53, indicated at least five recombination events between the aforementioned adenoviruses. Intrahexon recombination sites perfectly framed the ε neutralization determinant that was almost identical to the HAdV-D22 prototype. Additional bootscan analysis of all HAdV-D hexon genes revealed recombinations in identical locations in several other adenoviruses. In addition, HAdV-D53 but not HAdV-D22 induced corneal inflammation in a mouse model. Serological analysis confirmed previous results and demonstrated that HAdV-D53 has a neutralization profile representative of the ε determinant of its hexon (HAdV-D22) and the fiber (HAdV-D8) proteins. Our recombinant hexon sequence is almost identical to the hexon sequences of the HAdV-D strain causing EKC outbreaks in Japan, suggesting that HAdV-D53 is pandemic as an emerging EKC agent. This documents the first genomic, bioinformatic, and biological descriptions of the molecular evolution events engendering an emerging pathogenic adenovirus.

Hepatitis E virus infection as a cause of graft hepatitis in liver transplant recipients

Hepatitis E virus (HEV) infection induces self‐limiting liver disease in immunocompetent individuals. Cases of chronic hepatitis E have recently been identified in organ transplant recipients. We questioned if chronic hepatitis E plays a role in graft hepatitis after liver transplantation in a low endemic area. Two hundred twenty‐six liver transplant recipients, 129 nontransplanted patients with chronic liver disease, and 108 healthy controls were tested for HEV antibodies. HEV RNA was investigated in all sera from transplanted patients. HEV antibodies were detected in 1 healthy control (1%), 4 patients with chronic liver disease (3%), and 10 liver transplant recipients (4%). Three liver transplant patients also tested positive for HEV RNA. Two of them developed persistent viremia with HEV genotype 3. The patients were anti‐HEV immunoglobulin G–negative and HEV RNA–negative before transplantation and had an episode of acute hepatitis 5 or 7 months after transplantation, which led to advanced liver fibrosis after 22 months in 1 patient. Seroconversion to anti‐HEV occurred not before 4 months after the first detection of HEV RNA. The possibility of reverse zoonotic transmission was experimentally confirmed by the infection of 5 pigs with a patients serum. The pigs showed histological inflammation in the liver, and HEV RNA was detectable in different organs, including muscle. In conclusion, the prevalence of HEV infection in Central European liver transplant recipients is low; however, chronic hepatitis E may occur and needs to be considered in the differential diagnosis of graft hepatitis. The diagnosis of HEV infection should be based on HEV RNA determination in immunosuppressed patients. We suggest that immunocompromised individuals should avoid eating uncooked meat and contact with possibly HEV‐infected animals. Liver Transpl 16:74–82, 2010.

Phylogenetic Analysis of the Main Neutralization and Hemagglutination Determinants of All Human Adenovirus Prototypes as a Basis for Molecular Classification and Taxonomy

ABSTRACT Human adenoviruses (HAdV) are responsible for a wide spectrum of diseases. The neutralization ε determinant (loops 1 and 2) and the hemagglutination γ determinant are relevant for the taxonomy of HAdV. Precise type identification of HAdV prototypes is crucial for detection of infection chains and epidemiology. ε and γ determinant sequences of all 51 HAdV were generated to propose molecular classification criteria. Phylogenetic analysis of ε determinant sequences demonstrated sufficient genetic divergence for molecular classification, with the exception of HAdV-15 and HAdV-29, which also cannot be differentiated by classical cross-neutralization. Precise sequence divergence criteria for typing (<2.5% from loop 2 prototype sequence and <2.4% from loop 1 sequence) were deduced from phylogenetic analysis. These criteria may also facilitate identification of new HAdV prototypes. Fiber knob (γ determinant) phylogeny indicated a two-step model of species evolution and multiple intraspecies recombination events in the origin of HAdV prototypes. HAdV-29 was identified as a recombination variant of HAdV-15 (ε determinant) and a speculative, not-yet-isolated HAdV prototype (γ determinant). Subanalysis of molecular evolution in hypervariable regions 1 to 6 of the ε determinant indicated different selective pressures in subclusters of species HAdV-D. Additionally, γ determinant phylogenetic analysis demonstrated that HAdV-8 did not cluster with -19 and -37 in spite of their having the same tissue tropism. The phylogeny of HAdV-E4 suggested origination by interspecies recombination between HAdV-B (hexon) and HAdV-C (fiber), as in simian adenovirus 25, indicating additional zoonotic transfer. In conclusion, molecular classification by systematic sequence analysis of immunogenic determinants yields new insights into HAdV phylogeny and evolution.

Basal Core Promoter and Precore Mutations in the Hepatitis B Virus Genome Enhance Replication Efficacy of Lamivudine-Resistant Mutants

ABSTRACT During chronic hepatitis B virus (HBV) infection, mutations in the precore (PC) or basal core promoter (BCP) region affecting HBV e antigen (HBeAg) expression occur commonly and represent the predominant virus species in patients with HBeAg-negative chronic hepatitis B. The PC mutation (G1896A+C1858T) creates a translational stop codon resulting in absent HBeAg expression, whereas BCP mutations (A1762T/G1764A) reduce HBeAg expression by transcriptional mechanisms. Treatment of chronic HBV infection with lamivudine (LMV) often selects drug-resistant strains with single (rtM204I) or double (rtL180M+rtM204V) point mutations in the YMDD motif of HBV reverse transcriptase. We cloned replication-competent HBV vectors (genotype A, adw2) combining mutations in the core (wild type [wt], PC, and BCP) and polymerase gene (wt, rtM204I, and rtL180M/M204V) and analyzed virus replication and drug sensitivity in vitro. Resistance to LMV (rtM204I/rtL180M+rtM204V) was accompanied by a reduced replication efficacy as evidenced by reduced pregenomic RNA, encapsidated progeny DNA, polymerase activity, and virion release. PC mutations alone did not alter virus replication but restored replication efficacy of the LMV-resistant mutants without affecting drug resistance. BCP mutants had higher replication capacities than did the wt, also in combination with LMV resistance mutations. All nine HBV constructs showed similar sensitivities to adefovir. In conclusion, BCP-PC mutations directly impact the replication capacity of LMV-resistant mutants. PC mutations compensated for replication inefficiency of LMV-resistant mutants, whereas BCP mutations increased viral replication levels to above the wt baseline values, even in LMV-resistant mutants, without affecting drug sensitivity in vitro. Adefovir may be an effective treatment when combinations of core and polymerase mutations occur.

Chronic Hepatitis E in Heart Transplant Recipients

Chronic courses of hepatitis E virus (HEV) infections have been described in immunosuppressed patients. We aimed to study the role of HEV infections in heart transplant recipients (HTR). 274 HTR were prospectively screened for HEV infection using an anti‐HEV‐IgG ELISA and HEV‐PCR. In addition, 137 patients undergoing cardiac surgery (non‐HTR) and 537 healthy subjects were studied cross‐sectionally. The anti‐HEV‐IgG seroprevalence was 11% in HTR, 7% in non‐HTR and 2% in healthy controls (HTR vs. healthy controls p<0.0001; non‐HTR vs. healthy controls p<0.01). Anti‐HEV tested positive in 4.0% in control cohorts of other immunocompromised patients (n = 474). Four HTR (1.5%) were chronically infected with HEV as shown by HEV‐PCR and all four patients had liver transaminases of >200 IU/L and histological or clinical evidence of advanced liver disease. In three patients ribavirin treatment was successful with a sustained biochemical and virological response while treatment failed in one cirrhotic patient after ribavirin dose reduction. Heart transplant recipients and patients undergoing cardiac surgery have an increased risk for HEV infections. Chronic hepatitis E may explain elevated liver enzymes in heart transplant recipients. Treatment of HEV infection with ribavirin is effective but the optimal dose and duration of ribavirin therapy remains to be determined.

Prevalence, quantification and typing of adenoviruses detected in river and treated drinking water in South Africa

Aims:  Human adenoviruses (HAds), of which there are 51 serotypes, are associated with gastrointestinal, respiratory, urinary tract and eye infections. The importance of water in the transmission of HAds and the potential health risks constituted by HAds in these environments are widely recognized. Adenoviruses have not previously been quantified in river and treated drinking water samples. In this study, HAds in river water and treated drinking water sources in South Africa were detected, quantified and typed.

Monitoring of Adenovirus Infection in Pediatric Transplant Recipients by Quantitative PCR: Report of Six Cases and Review of the Literature

Adenoviral (AdV) infections after transplantation remain a challenge in pediatric patients. Qualitative and quantitative PCR offer new approaches to early diagnosis and monitoring. However, their role in the management of AdV infections in pediatric transplant recipients remains to be determined.

Rapid routine detection of enterovirus RNA in cerebrospinal fluid by a one-step real-time RT-PCR assay

BACKGROUND AND OBJECTIVES This study provides a one-step transcription/real-time (TaqMan probe) PCR assay (TM-PCR) with new consensus primer and probe sequences for generic detection of human pathogenic enteroviruses including difficult to detect ones like for instance Echovirus 30. The amplicon included parts of domain IV and V of the highly conserved internal ribosomal entry site. Generic detection was confirmed by testing a panel of 41 prototypes representing all five human enterovirus/poliovirus species. STUDY DESIGN AND RESULTS The 95% detection limit was found to be 100 copies per run using in vitro transcribed coxsackievirus B3 RNA. TM-PCR was compared to an in house nested-PCR assay implemented in detecting enterovirus RNA from CSF samples of patients suffering from meningitis and encephalitis. Concordant results were obtained in all samples (11 positive, 101 negative). Specificity was confirmed with laboratory strains of other neurotropic viruses, and by testing 76 CSF samples of patients with encephalomyelitis disseminata, which all gave negative results. CONCLUSIONS The new TM-PCR is a convincing alternative to conventional PCR protocols for the diagnosis of enterovirus meningitis. The one-step strategy limits hands on time and cross contamination risk combined with accelerated assay procedure of only 100 min.

Rapid quantitative PCR assays for the simultaneous detection of herpes simplex virus, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, and human herpesvirus 6 DNA in blood and other clinical specimens

Rapid diagnosis of human herpesvirus primary infections or reactivations is facilitated by quantitative PCRs. Quantitative PCR assays with a standard thermal cycling profile permitting simultaneous detection of herpes simplex virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein‐Barr virus (EBV), and human herpesvirus 6 (HHV6) DNA were developed and validated for diagnostic use. High specificity and sensitivity were achieved and the new PCR assays correlated well with commercial PCR assays. Twenty two thousand eight hundred sixty eight PCR tests were undertaken on specimens obtained from immunosuppressed patients. DNAemia was frequent with EBV (43.5%), HHV6 (32.4%), CMV (12.8%), and VZV (12.9%). As already described for EBV and CMV, high virus loads of HHV6 and VZV were associated with clinical symptoms and poor clinical outcome, for example, three of four patients with VZV virus loads >105 copies/ml died. A high proportion of lower respiratory specimens was positive for EBV‐ (38.8%), HHV6‐ (29.4%), and CMV‐DNA (18.2%). For CMV, infection was confirmed in 66.7% of patients by virus isolation or positive pp65 antigenaemia. Differentiation of HHV6A, ‐B and HSV‐1, ‐2 by melting curve analysis revealed that HHV6A and HSV‐2 represented only 1.8% and 3.3% of all positive specimens, respectively. In conclusion, these results indicate significant improvements for the early diagnosis of primary infections or reactivations of five human herpesviruses especially in immunosuppressed patients. Detection of coinfections with multiple herpesviruses is facilitated. Quantitative results enable monitoring of virus load during antiviral therapy. A standard thermal cycling profile permits time and cost effective use in a routine diagnostic setting. J. Med. Virol. 80:467–477, 2008.

Varicella vaccination in a child with acute lymphoblastic leukaemia

In July, 2003, during reinduction treatment 5 months after diagnosis of acute lymphoblastic leukaemia (ALL), a 4-yearold girl presented with generalised tonic-clonic seizures. She had been treated according to protocol ALL-BFM 2000. Cranial CT and analysis of cerebrospinal fl uid showed no signs of cerebral haemorrhage. Ultra sonography showed an enlarged liver and no signs of ascites or veno-occlusive disease. Her skin appeared normal, with no vesicular rashes. Blood tests showed only raised concentrations of aminotransferases. During the next few hours, she developed respiratory insuffi ciency, petechiae, haematomas, and vesicular lesions of the oral and vagi nal mucosal. On the assumption of an underlying infec tious cause, intravenous treatment with piperacillin, sulbactam, tobramycin, IgG, and aciclovir was initiated. 48 h after the fi rst seizure, her laboratory test results deteriorated, with aspartate and alanine aminotransferase concentrations increasing to 20 864 U/L and 16 029 U/L, respectively, and the full blood cell count indicated pancytopenia. Within 12 h, she developed multi-organ failure (liver, renal, and circulatory failure, and acute respiratory distress syndrome [ARDS]), necessitating artifi cial ventilation. Serostatus for varicella-zoster virus (VZV) was negative, but PCR for VZV was positive in peripheral blood samples (7×106 genome copies per mL). VZV was also isolated from a nasopharyngeal swab but not from cerebrospinal fl uid. PCR analysis of peripheral blood was negative for hepatitis B and C viruses, herpes simplex virus 1 and 2, Epstein-Barr virus, cytomegalovirus, adenovirus, enterovirus, human herpes virus 6, and parvovirus B19. High doses of VZVIgG were added to the treatment. Despite haemo dialysis and ventilation, the child died of progressive ARDS and multi-organ failure 10 days after admission. On receiving the positive VZV-PCR results, the mother recalled that her daughter had received live attenuated VZV vaccine (Varilrix) at another hospital 32 days before the onset of symptoms. Partial sequencing of VZV genes 38 and 54 isolated from the patient excluded a wild-type VZV infection and showed that viraemia was caused by the VZV vaccine strain OKA (fi gure). Vaccination was done 5 months after complete remission had been achieved; at that time lymphocyte count was more than 1·5×109/L, and chemotherapy was interrupted for 1 week before and after vaccination. Deaths after vaccinations with numerous attenuated viruses are well established. Fatal wild-type VZV infections have been reported in ALL patients during chemotherapy and after bone-marrow cell transplantation. Therefore, VZV vaccination is a useful, and generally accepted, therapeutic measure for patients with ALL in remission. Studies of VZV vaccination 3–4 months after autologous stem-cell transplantation, and in early ALL maintenance therapy, did not show fatal side-eff ects. However, any interruption of maintenance therapy in ALL can adversely aff ect outcome for the patient. In our patient, liver failure developed 5 weeks after VZV vaccination, which indicates longstanding replication of OKA strain in the liver. This suggestion accords with observations of late onset of complications (fever, vesicles, and severe hepatitis) in immunocompromised patients after VZV vaccination. Therefore, although we cannot fully exclude that intensifi cation of chemotherapy could have aggravated her symptoms, we suggest that VZV vaccination in seronegative children with leukaemia, who are in complete remission for at least 12 months, should not be undertaken until at least 9 months after the end of immunosuppressive treatment (including maintenance therapy) and not before a lymphocyte count of at least 1·5×109/L has been ascertained. In addition, high-risk patients should remain under close surveillance in the critical phase (6 weeks after vaccination) so that immediate antiviral treatment with aciclovir can be initiated in symptomatic children.