Herpesviruses

High intrahepatic HHV-6 virus loads but neither CMV nor EBV are associated with decreased graft survival after diagnosis of graft hepatitis

BACKGROUND & AIMS

In liver transplant recipients with graft hepatitis, the relevance of herpesviruses is not well defined.

METHODS

Viral loads of CMV, EBV, and HHV-6 were determined in blood and liver biopsies of 170 liver transplant recipients with graft hepatitis by quantitative PCR.

RESULTS

HHV-6-, CMV-, and EBV-DNA were detected in 58%, 14%, and 44% of the biopsies, respectively, with coinfections in 34%. High intrahepatic HHV-6 DNA levels (>75th percentile, 11.27 copies/1000 cells) and detection of HHV-6 DNAemia were significantly associated with decreased graft survival after diagnosis of graft hepatitis (p=0.014 and p=0.003, respectively, median follow-up was 23.8 months). Multivariate analysis confirmed high intrahepatic HHV-6 loads as an independent factor associated with reduced graft survival (adjusted hazard ratio 2.61, 95%confidence interval 1.16-5.87). Low concentrations of HHV6 DNA in the liver, indicating latent infection, did not influence graft survival. Neither CMV nor EBV (qualitative detection and high virus loads) nor acute rejection (according to the BANFF score) affected graft survival. However, patients had been treated for CMV reactivations and acute rejections in this retrospective study. High age and high bilirubin levels were the other independent factors associated with reduced graft survival (adjusted hazard ratio 3.56CI 1.52-8.34 and 3.23CI 1.50-6.96, respectively).

CONCLUSIONS

High intrahepatic HHV-6-DNA levels are associated with decreased graft survival in liver transplant recipients with graft hepatitis. The significance of HHV-6 as potential etiology of graft hepatitis needs further evaluation.

Measurement of Epstein-Barr virus DNA load using a novel quantification standard containing two EBV DNA targets and SYBR Green I dye

Background

Reactivation of Epstein-Barr virus (EBV) infection may cause serious, life-threatening complications in immunocompromised individuals. EBV DNA is often detected in EBV-associated disease states, with viral load believed to be a reflection of virus activity. Two separate real-time quantitative polymerase chain reaction (QPCR) assays using SYBR Green I dye and a single quantification standard containing two EBV genes, Epstein-Barr nuclear antigen-1 (EBNA-1) and BamHI fragment H rightward open reading frame-1 (BHRF-1), were developed to detect and measure absolute EBV DNA load in patients with various EBV-associated diseases. EBV DNA loads and viral capsid antigen (VCA) IgG antibody titres were also quantified on a population sample.

Results

EBV DNA was measurable in ethylenediaminetetraacetic acid (EDTA) whole blood, peripheral blood mononuclear cells (PBMCs), plasma and cerebrospinal fluid (CSF) samples. EBV DNA loads were detectable from 8.0 × 10² to 1.3 × 10⁸ copies/ml in post-transplant lymphoproliferative disease (n = 5), 1.5 × 10³ to 2.0 × 10⁵ copies/ml in infectious mononucleosis (n = 7), 7.5 × 10⁴ to 1.1 × 10⁵ copies/ml in EBV-associated haemophagocytic syndrome (n = 1), 2.0 × 10² to 5.6 × 10³ copies/ml in HIV-infected patients (n = 12), and 2.0 × 10² to 9.1 × 10⁴ copies/ml in the population sample (n = 218). EBNA-1 and BHRF-1 DNA were detected in 11.0% and 21.6% of the population sample respectively. There was a modest correlation between VCA IgG antibody titre and BHRF-1 DNA load (rho = 0.13, p = 0.05) but not EBNA-1 DNA load (rho = 0.11, p = 0.11).

Conclusion

Two sensitive and specific real-time PCR assays using SYBR Green I dye and a single quantification standard containing two EBV DNA targets, were developed for the detection and measurement of EBV DNA load in a variety of clinical samples. These assays have application in the investigation of EBV-related illnesses in immunocompromised individuals.

Multiplex real-time PCR for the simultaneous detection of herpes simplex virus, human herpesvirus 6, and human herpesvirus 7

A simultaneous detection system to quantify HSV, HHV-6, and HHV-7 DNA via multiplex real-time PCR using different fluorochromes was developed. The minimum quantitative level established via this multiplex assay was four copies per reaction for HSV type 1, four copies for HHV-6, and three copies for HHV-7, respectively. The dynamic range encompassed at least six orders of magnitude. The system was specific and reproducible even in the presence of large amounts of other viral DNA. We then applied this multiplex real-time PCR assay to 105 CSF specimens obtained from subjects less than 15 years old in whom a diagnosis of viral encephalitis/encephalopathy was suspected on clinical grounds. The detection rate for each viral DNA was 6.7% for HSV, 9.5% for HHV-6, and 1.9% for HHV-7. These results indicate that our system is reliable and may be useful for the rapid diagnosis of viral encephalitis/encephalopathy.

Quantitative measurement of varicella-zoster virus infection by semiautomated flow cytometry

Varicella-zoster virus (VZV; human herpesvirus 3) is the etiological cause of chickenpox and, upon reactivation from latency, zoster. Currently, vaccines are available to prevent both diseases effectively. A critical requirement for the manufacturing of safe and potent vaccines is the measurement of the biological activity to ensure proper dosing and efficacy, while minimizing potentially harmful secondary effects induced by immunization. In the case of live virus-containing vaccines, such as VZV-containing vaccines, biological activity is determined using an infectivity assay in a susceptible cellular host in vitro. Infectivity measurements generally rely on the enumeration of plaques by visual inspection of an infected cell monolayer. These plaque assays are generally very tedious and labor intensive and have modest throughput and high associated variability. In this study, we have developed a flow cytometry assay to measure the infectivity of the attenuated vaccine strain (vOka/Merck) of VZV in MRC-5 cells with improved throughput. The assay is performed in 96-well tissue culture microtiter plates and is based on the detection and quantification of infected cells expressing VZV glycoproteins on their surfaces. Multiple assay parameters have been investigated, including specificity, limit of detection, limit of quantification, range of linear response, signal-to-noise ratio, and precision. This novel assay appears to be in good concordance with the classical plaque assay results and therefore provides a viable, higher-throughput alternative to the plaque assay.

Simultaneous quantification of Epstein-Barr virus, cytomegalovirus, and human herpesvirus 6 DNA in samples from transplant recipients by multiplex real-time PCR assay

We developed a multiplex real-time PCR assay using 6-carboxyfluorescein, 6-carboxy-4',5'-dichloro-2',7'-dimethoxyfluorescein, and carbocyanine 5-labeled probes to simultaneously quantify Epstein-Barr virus (EBV), cytomegalovirus (CMV), and human herpesvirus 6 (HHV-6) DNA. When previously tested and stored DNA samples were examined, results of the multiplex real-time PCR assay were as sensitive and specific as those of a single real-time PCR assay. The multiplex assay was used to quantify the EBV, CMV, and HHV-6 DNA in 46 transplant recipients. A total of 303 whole-blood and plasma specimens were collected and analyzed. According to the results of the multiplex assay, the detection rates for viral DNA in whole blood and plasma were 23.8% and 5.9% for EBV, 11.2% and 5.3% for CMV, and 12.5% and 2.0% for HHV-6, respectively. All forms of viral DNA were detected more frequently in whole blood than in plasma. During the symptomatic period, EBV DNA was detected in all whole-blood specimens but not in all plasma specimens. Furthermore, the EBV DNA load in whole blood was higher during the symptomatic period than during the asymptomatic period, whereas the EBV DNA load in plasma was similar for both periods. These results demonstrate that whole blood is more suitable for the quantification of EBV DNA in transplant patients. However, a cutoff value with clinical relevance still needs to be determined.

The prevalence of recurrent herpes labialis during an army hot weather exercise

A survey was performed on 1,062 of 2,500 (42%) Army personnel participating in a desert training exercise at Fort Irwin, California, in September 1983. The prevalence of recurrent herpes labialis (RHL) and chapped lips was observed during the third week of a four-week training period. Complexion, sex, lip protectant use, age, and time spent outdoors were obtained by observation and interview. Recurrent herpes labialis was found in 46 subjects (4%). Stratified analysis and stepwise logistic regression were used to identify risk factors associated with RHL and to determine the prevalence odds ratios (POR). Risk factors with statistically significant associations with RHL were lip protectant use (POR = 0.19), chapped lips (POR = 2.87), being female (POR = 5.00), and light complexion (POR = 2.48). These findings strongly support the use of lip protectants during prolonged exposure to hot, dry climates as a prophylaxis against recurrent herpes labialis. Additional studies should focus on excitatory factors of RHL; and clinical trials of the efficacy of the lip protectants to protect against RHL and chapped lips should be undertaken.

Herpes simplex virus infections in male and female mice following pinna inoculation: responses to primary infection and artificially induced recurrent disease

The pathogenesis of herpes simplex virus (HSV) infection is now well understood. After humans or experimental animals recover from primary infection, the virus remains latent in sensory ganglia of the peripheral nervous system. Latency, for the most part, remains unresolved, and elucidating the mechanisms involved with latency has proved difficult. The requirement for unravelling HSV latency is the availability of a reproducible animal model. Previously, the mouse ear model has been extensively characterized; however, many studies using this model have involved female mice only despite evidence that recurrent HSV infection in humans may vary by gender. We inoculated male and female mice subcutaneously in the pinna with varying amounts of one of four strains of HSV and monitored the mice for signs of primary infection. Following recovery from primary infection, mice were induced to develop recurrent disease. In addition, we attempted to isolate virus from dorsal root ganglia of mice suspected of harboring latent virus. There were no differences in the response of male and female mice to either primary infection or artificially induced recurrent disease when inoculated with the same virus. Differences were noted when female mice were inoculated with different strains of virus.

Response of early disseminated Herpes simplex to acycloguanosine: a case report

Acycloguanosine, an anti-viral agent with few side effects and good activity in vitro against Herpes simplex, has not produced a consistently high cure rate in clinical practice (1). This may in part be related to delayed initiation of therapy (2). We describe a case of disseminated Herpes simplex (DHS) in an immunocompromised child (which is normally associated with a fatal outcome) who responded rapidly and completely to treatment with acycloguanosine.