Virological analysis of inherited chromosomally integrated human herpesvirus-6 in three hematopoietic stem cell transplant patients.

We analyzed 3 hematopoietic stem cell transplant (HSCT) recipients with inherited chromosomally integrated human herpesvirus-6 (inherited CIHHV-6). Cases 1 (inherited CIHHV-6A) and 2 (inherited CIHHV-6B) were inherited CIHHV-6 recipients. Case 3 received bone marrow from a donor with inherited CIHHV-6B. Following HSCT, HHV-6B was isolated from Case 1. HHV-6A and -6B messenger RNAs were detected in Cases 1 and 3.

Analysis of rotavirus antigenemia in hematopoietic stem cell transplant recipients.

Systemic rotavirus infection, such as rotavirus antigenemia, has been found in immunocompetent rotavirus gastroenteritis patients. However, the pathogenesis of rotavirus infection in immunocompromised transplant recipients remains unclear. Enzyme-linked immunosorbent assay was used to measure rotavirus antigen levels in serially collected serum samples obtained from 62 pediatric patients receiving allogeneic hematopoietic stem cell transplants (HSCT). Rotavirus antigen was detected in 43 (6.8%) of 633 serum samples (8 of 62 patients). The duration of rotavirus antigenemia ranged between 1 and 10 weeks, and diarrhea was concurrent with rotavirus antigenemia in Cases 3, 6, 7, and 8. The level of viral antigen in the transplant recipients (0.19 ± 0.20) was significantly lower than that observed in serum samples collected from immunocompetent patients on either day 1 (0.49 ± 0.18, P = 0.0011) or day 3 (0.63 ± 0.09, P = 0.0005). A patient who received a graft from a human leukocyte antigen (HLA)-mismatched donor was at significant risk for rotavirus antigenemia (P = 0.024; odds ratio = 9.44) in comparison to patients who received grafts from HLA-matched donors. Although the duration of antigenemia was clearly longer in HSCT patients than in immunocompetent rotavirus gastroenteritis patients, the levels of viral antigen were not as high. Therefore, mismatched HLA may be a risk factor for rotavirus antigenemia after HSCT.

Nosocomial infection with rotavirus vaccine strain in paediatric patients with immunodeficiency.

In infants with immunodeficiency, rotavirus (RV) vaccines can be continuously excreted in stool. We analysed nosocomial infection with RV vaccine strain in immunodeficient paediatric patients. RV1 RNAs were detected in stool and serum samples from case A, who was vaccinated with RV1, and case B, who was not. PAGE analysis of serial stool samples of case A revealed several rearrangements of the RV genome. In case B, the only band pattern detected was the same as a rearrangement detected in case A at the same time. In summary, RV vaccination of infants with immunodeficiency poses a risk of nosocomial infections.

Four cases of human herpesvirus 6 variant B infection after pediatric liver transplantation.

BACKGROUND: Little is known about human herpesvirus (HHV)-6 infection after liver transplantation. We present our experiences with four cases of HHV-6 infection after liver transplantation from living related donors. METHODS: Peripheral blood was collected from four donor and recipient pairs at the time of transplantation and biweekly from the recipients after transplantation. We attempted to isolate HHV-6 and measure antibody titers to HHV-6 and HHV-7. RESULTS: HHV-6 was isolated from four recipients approximately 2 weeks after transplantation. A significant rise in HHV-6 antibody titers was observed in four recipients at some point in their course, whereas HHV-7 antibody titers were increased in one recipient. Four isolates were variant B. When HHV-6 was isolated, all recipients had an unexplained fever. CONCLUSIONS: HHV-6 variant B infection after pediatric liver transplantation was confirmed. HHV-6 infection occurred approximately 2 weeks after transplantation. Moreover, there appears to be an association between HHV-6 infection and unexplained fever.

Transfer of human herpesvirus 6 and 7 antibodies from mothers to their offspring.

Placental transfer of maternal human herpesvirus (HHV) 6 and HHV 7 antibodies to infants was examined simultaneously in 69 paired plasma samples by an indirect immunofluorescence assay. All the mothers had antibodies to both viruses. The mean HHV 6 and HHV 7 antibody titers of infants were significantly higher than those of the mothers. The mean ratio of cord blood antibody titer to the maternal titer for both viruses was 1.89, suggesting active transport by placenta.

Correlation between HHV-6 infection and skin rash after allogeneic bone marrow transplantation.

We investigated whether a causal relationship exists between human herpesvirus 6 (HHV-6) and skin rash resembling acute graft-versus-host disease (GVHD) following bone marrow transplantation (BMT). Isolation of HHV-6 was used to monitor active HHV-6 infection in this study. We analyzed 25 episodes of skin rash in 22 recipients. All recipients were seropositive for HHV-6 before BMT. The onset of skin rash started prior to 30 days post transplantation (group A) in 15 of 25 cases, but after that (group B) in the remaining 10 cases. Twenty-five skin tissue samples were obtained from 22 recipients. The HHV-6 genome was detected in four of 15 skin samples from group A, but not detected in those from group B. HHV-6 was isolated from 11 of 22 recipients around 2 to 3 weeks after BMT (range 14 to 28 days after BMT). HHV-6 was isolated at a time between 10 days before and after the onset of skin rash (skin rash-related viremia) in nine cases in group A. Meanwhile, no skin rash-related viremia was observed in group B. Of the four recipients with positive detection of HHV-6 genome in their skin tissue (group A), two had HHV-6 viremia at the same time. The association between the timing of HHV-6 infection and the onset of skin rash was analyzed statistically. HHV-6 viremia (skin rash-related viremia) was found in nine of 15 (60%) cases in group A, compared with none of 10 (0%) cases in group B. This difference was statistically significant (P = 0.008). Moreover, HHV-6 infection (skin rash-related viremia and/or positive detection of HHV-6 DNA in skin tissue) was demonstrated in 11 of 15 (73.3%) cases in group A, compared with none of 10 (0%) cases in group B (P = 0.001). Thus, this study suggests that HHV-6 may be involved in the development of skin rash in the first month after allogeneic BMT.

Human herpesvirus 6 latently infects mononuclear cells but not liver tissue.

AIM: To investigate whether human herpesvirus 6 (HHV-6) can cause latent infection of liver tissue. METHODS: Peripheral blood and liver tissue were collected from 25 living related liver transplant recipients at the time of transplantation. An avidin-biotin complex peroxidase method was used to identify HHV-6 antigen in the liver tissue. A nested polymerase chain reaction (PCR) was used to detect HHV-6 DNA in the liver tissue and mononuclear cells. Variant of HHV-6 was determined by the presence of the Hind III site in a second PCR product. RESULTS: Immunohistochemical analysis for HHV-6 antigen was negative in all the liver specimens. HHV-6 DNA was not detected in liver tissue. Virus DNA was detected in peripheral blood mononuclear cells in nine of 25 recipients. All nine HHV-6 identified in the mononuclear cells were variant B. CONCLUSIONS: HHV-6 variant B latently infects mononuclear cells but not liver tissue.

Fatal acute myocarditis in an infant with human herpesvirus 6 infection.

A 5 month old girl had typical clinical features of acute myocarditis just after the febrile period of exanthem subitum and died immediately. She had been healthy, with normal development, and there was no family history of particular note. Myocardial postmortem findings were compatible with acute myocarditis. Although the isolation of human herpesvirus 6 (HHV-6) was not attempted, positive IgM antibody to HHV-6 was detected in the patient's serum. Moreover, HHV-6 variant B DNA was detected in several tissues, including myocardium, by the polymerase chain reaction (PCR). In contrast, antibody responses to human herpesvirus 7, another causal agent of exanthem subitum, were not found, and enteroviral RNA was not detected in myocardial tissues by reverse transcription PCR. Apoptotic changes were seen in infiltrating cells within the myocardial tissues by means of the TUNEL method. HHV-6 antigen was not detected in several tissues (including myocardium) by immunohistochemical analysis. In conclusion, HHV-6 may have been the causative agent of fatal acute myocarditis in this infant.

[Clinical features of primary HHV-6 and HHV-7 infections].

Human herpesvirus-6 (HHV-6), a T-lymphotropic herpesvirus, belongs to one of two variants, A or B (HHV-6A and HHV-6B). HHV-6B is the cause of exanthem subitum (ES) which had a wide spectrum of related illnesses in the central nervous system, gastrointestinal tract, respiratory tract, and blood cells including fatal outcome, however, a clear etiologic role has not been identified for HHV-6A. HHV-6 is ubiquitous and primary infection with the virus almost always occurs before the age of 2 years. On the other hand, human herpesvirus-7 (HHV-7), isolated from CD4+ T lymphocytes from the peripheral blood of a healthy individual has been recognized as a new lymphotropic herpesvirus. The virus was distinct from the six previously identified human herpesviruses and had limited homology to human cytomegalovirus and HHV-6 by both molecular and immunological analyses. Healthy adults frequently shed the virus into saliva, and children are infected at a young age but somewhat later than HHV-6B. The primary infection with HHV-7 is linked to febrile illness with or without rash that resembles ES. A consensus is needed on whether the term should be used only for clinical features by primary infection with HHV-6 or for clinical syndromes featuring febrile exanthem by various infectious agents including HHV-6, HHV-7, enteroviruses, etc.

Invasion by human herpesvirus 6 and human herpesvirus 7 of the central nervous system in patients with neurological signs and symptoms.

METHODS: A total of 43 children with neurological signs and symptoms were enrolled in the study. All children were suspected of having meningitis, and lumbar punctures were performed. Human herpesvirus 6 (HHV-6) and HHV-7 DNA was detected in cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMC) by nested polymerase chain reaction. RESULTS: Most patients had detectable serum antibody to both HHV6 and 7. HHV6 DNA was detected in PBMC of 15 patients and in CSF cell pellet of seven. Corresponding figures for HHV7 were 28 and 6.2/7, and 5/6 with CSF viral DNA also had it in PBMC, respectively. No viral DNA was detected in CSF supernatants. The seven HHV6 CSF viruses were all variant B. CONCLUSION: These data suggest that HHV-7 may invade the CNS.

Spread of varicella-zoster virus DNA to family members and environments from siblings with varicella in a household.

OBJECTIVE: To elucidate virus spread from siblings with varicella to other family members and environmental objects in a family setting before and after onset of the disease. MATERIALS AND METHODS: Among a family consisting of five members, a boy developed varicella and the remaining two siblings developed the disease 17 and 18 days after onset of the index case. Swab samples from throats and hands of parents and three siblings and samples from several sources in the environment of the house were collected frequently before and/or after onset of the disease. Varicella-zoster virus (VZV) DNA in the samples was examined by a sensitive polymerase chain reaction amplification assay. RESULTS: In total, 108 samples from the throats and hands of the three children with varicella, 72 such samples from parents, and 72 samples from the surfaces of several sources in the house were collected. Eight days after onset of the index case (the older boy), VZV DNA was detected in both samples from the index case and on the surfaces of four sources (air conditioner filter, table, television channel push-buttons, and door handle), but not from the two other siblings or parents. Then, it was detected once on the mother's hand and the air conditioner filter and three times on the television channel push-buttons by January 30, 1998, when the girl developed varicella, 17 days after onset of the index case. The younger brother developed the disease on January 31. Viral DNA could not be detected in any samples obtained on January 30; however, it was detected on the hands of the older boy and the father and in samples from the hand and throat of the girl on January 31. Thereafter, virus DNA was detected three times intermittently by February 13 on the hand and three times persistently in the throat of the girl. The virus DNA was detected three times between February 1 and 3 on the hand and three times between February 1 and 4 in the throat of the younger boy. It was detected occasionally on the hands of the older boy and the parents, and occasionally or intermittently on surfaces of four environmental sources between February 2 and 13. CONCLUSIONS: The present study showed the rapid and broad contamination of the environment with the VZV DNA when the varicella patient appeared in a family, although it does not directly mean infectivity.

Rapid contamination of the environments with varicella-zoster virus DNA from a patient with herpes zoster.

Patients with zoster are considered to be less contagious than varicella patients because their infection is localised. It is not known, however, when and for how long a spread of varicella-zoster virus (VZV) from a zoster patient begins and continues and the extent of virus spread from the patient. The polymerase chain reaction (PCR) was used to detect VZV DNA in samples obtained from the hands and throat of a patient with zoster and from her room environments including surfaces of the back of a chair, the door handle, the table and the air conditioner filter. VZV DNA was detected on the surfaces of the back of the seat and the table and in peripheral blood mononuclear cells (PBMCs) and serum on Day 4 of the illness. VZV DNAemia persisted for 4 days until Day 7 of the illness. It was also detected in samples collected from throat and the air conditioner filter on Days 6 and 7 of the illness respectively. All of the surfaces, that were examined in her home environment, were contaminated with VZV DNA by Day 7 of the illness. The present study showed rapid and wide spread of VZV DNA in the environment even from a patient with zoster.

Human herpesvirus 6 infection after living related liver transplantation.

The aim of the study was to investigate human herpesvirus-6 (HHV-6) infection after liver transplantation from living related donors, and to evaluate the reliability of the presence of HHV-6 DNA in plasma by the polymerase chain reaction (PCR) for monitoring active HHV-6 infection. EDTA peripheral blood was collected from 47 donor and recipient (16 males and 31 females, age 1-320 months) pairs at the time of transplantation and biweekly from these recipients after transplantation until 2 months after operation. Isolation of HHV-6 and serological assays were carried out to evaluate active HHV-6 infection in this study. The presence of the viral DNA in plasma was tested by nested PCR. Four clinical events, such as unexplained fever, thrombocytopenia, rejection, and central nervous system (CNS) involvement, were evaluated for clinical features of the virus infection. Risk factors for the virus activity after liver transplantation were also examined. HHV-6 activity was detected in 23 (49%) of the 47 recipients approximately 2-4 weeks after transplantation. All 9 isolates were HHV-6 variant B. The presence of the viral DNA in plasma correlated well with virus isolation and serology (P < 0.01). Only unexplained fever was associated statistically with HHV-6 activity after liver transplantation (P < 0. 01). If the recipient was seronegative to HHV-6 before transplantation, the recipient was more likely to develop the active virus infection after liver transplantation (P = 0.11). HHV-6 activity occurred in one-half of the recipients approximately 2-4 weeks after liver transplantation, and there was a close association between HHV-6 activity and unexplained fever following transplantation. Detection of the viral DNA in plasma by PCR is useful for monitoring active HHV-6 infection in these patients. Seronegative recipients were more likely to have evidence of active HHV-6 infection after liver transplantation.

Clinical characteristics of febrile convulsions during primary HHV-6 infection.

OBJECTIVE: To clarify clinical characteristics of children with febrile convulsions during primary human herpesvirus 6 (HHV-6) infection. SUBJECTS AND METHODS: The clinical characteristics of first febrile convulsion were compared between those with and without primary HHV-6 infection in 105 children. HHV-6 infection was verified by culture or acute/convalescent anti-HHV-6 antibody titres. RESULTS: Primary infection with HHV-6 was seen in 21 of 105 patients with febrile convulsions (3 upper respiratory infection, 1 lower respiratory infection, and 17 exanthem subitum). 13 of 23 patients < 1 year, 19 of 79 patients with first febrile convulsion, and 2 of 15 with second convulsion were infected with HHV-6. The median age of patients with first febrile convulsion and HHV-6 was significantly lower than those without infection. The frequency of clustering seizures, long lasting seizures, partial seizures, and postictal paralysis was significantly higher among those with primary HHV-6 infection than among those without. The frequency of atypical seizures in 19 patients with first febrile convulsion associated with primary infection was significantly higher than in 60 patients without primary infection. The frequency in infants younger than 1 year of age was also significantly higher than that in 10 age matched infants without primary infection. CONCLUSIONS: These findings suggest that primary infection with HHV-6 is frequently associated with febrile convulsions in infants and young children and that it often results in the development of a more severe form of convulsions, such as partial seizures, prolonged seizures, and repeated seizures, and might be a risk factor for subsequent development of epilepsy.

Correlation between human herpesvirus 6 and 7 infections after living related liver transplantation.

Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) are closely related to each other. Interaction between the two viruses at the time of primary HHV-7 infection is suggested by in vivo and in vitro studies. However, interaction between the two viruses in organ transplant recipients has not been analyzed. We analyzed serially collected plasma samples obtained from 40 living related liver transplant recipients by serological assay (indirect immunofluorescence assay, IFA) and polymerase chain reaction (PCR). Significant increase or seroconversion of HHV-6 IgG and HHV-7 IgG antibody titers were observed in 45% and 58% of recipients respectively. Positive rate of IgM HHV-6 antibody increased up to 35% at 4 weeks after transplantation. However, no remarkable peak in the positive rate of HHV-7 IgM antibody was demonstrated. HHV-6 and HHV-7 DNA were detected in plasma in 15 (38%) and 16 (40%) of the 40 recipients respectively. HHV-6 DNA was detected in 10 (26%) of the 38 recipients at 2 weeks after transplantation. The positive rate of the virus genome in plasma gradually decreased after that time. HHV-7 DNA was detected in 5 (14%) of the 37 recipients at 2 weeks after transplantation; no obvious peak in the positive rate of HHV-7 DNA was demonstrated. Antibody responses involving both HHV-6 and HHV-7, including either a significant increase in IgG antibody titers or positive identification of IgM antibody were observed in 17 (43%) of the 40 recipients. Thirteen out of the 17 recipients demonstrated concurrent antibody response against both viruses. HHV-7 antibody response preceded the HHV-6 antibody response in 2 of the remaining 4 recipients, whereas the opposite was true in the other 2 recipients. Both HHV-6 and HHV-7 DNA were detected in 7 (18%) of the 40 recipients. In 4 of those 7 recipients, DNA from both viruses was concurrently detected, 3 of whom had HHV-7 DNA repeatedly detected after first detection of the virus DNA. The detection of HHV-7 DNA preceded the detection of HHV-6 DNA in 2 recipients, whereas HHV-6 DNA appeared first in 1 recipient.

Primary human herpesvirus 6 infection in liver transplant recipients.

We detected primary human herpesvirus 6 (HHV-6) infection in 5 infants who received living related liver transplantation from their HHV-6 seropositive mothers. Primary HHV-6 infection was confirmed by demonstrating the seroconversion of HHV-6 antibodies with an immunofluorescence assay, by the isolation of the virus, or both. Seroconversion of HHV-6 immunoglobulin G antibody was demonstrated in all 5 recipients. HHV-6 was isolated from 3 of the 5 recipients between 2 and 3 weeks after transplantation. Moreover, the virus genome was detected in plasma by polymerase chain reaction in 4 of the 5 recipients during the same period. Although the 5 recipients had pyrexia at the time of primary HHV-6 infection, none of the recipients had a skin rash after defervescence. Clinical symptoms disappeared without specific antiviral treatment in all but 1 of the recipients.

Quantitation of human herpesvirus 6 DNA in infant with exanthem subitum by microplate PCR-hybridization assay.

BACKGROUND: Quantitative analysis of human herpesvirus 6 (HHV-6) genome is important for monitoring active virus infection. The purpose of our study is to evaluate the reliability of a hybridization-based microtiter plate assay (polymerase chain reaction enzyme-linked immunosorbent assay (PCR ELISA)) for quantifying the virus genome. METHODS: Semiquantitative analysis of the virus genome was carried out in 31 (18 male and 13 female) infants with primary HHV-6 infection. If the HHV-6 virus could be isolated from the peripheral blood mononuclear cells (PBMC), the infants were defined as being infected with HHV-6. The PCR ELISA method was used to determine the virus load. A titration of the virus was also carried out in the samples obtained during the acute phase of exanthem subitum. RESULTS: Specificity of the method was demonstrated by a lack of amplification of human herpesvirus 7 and cytomegalovirus DNA. The upper and lower detection limits of the method were 58 and 5800 copies of the virus genome, respectively. The quantity of HHV-6 DNA in the PBMC during the acute phase (879 +/- 975 copies/10(4) PBMC) was significantly higher than during the convalescent phase (54 +/- 76 copies/10(4) PBMC). Furthermore, the virus load in acute phase plasma (53 +/- 75 copies/microL) was also significantly higher than in the convalescent phase samples (2 +/- 9 copies/microL). Virus load in both PBMC and plasma gradually increased after the onset of exanthem subitum until about day 3 to 4 of the illness, but then decreased quickly. However, there was no significant association between virus load and the numbers of infected cells. CONCLUSION: Virus load in both PBMC and plasma gradually increased after the onset of exanthem subitum until about day 3 and day 4 of the illness, respectively, then it decreased quickly. These results indicate that our PCR ELISA system is reliable for monitoring active HHV-6 infection in vivo.

Comparison of specific serological assays for diagnosing human herpesvirus 6 infection after liver transplantation.

Cross-reactivity between human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) antibodies and the reliability of specific serological assays were analyzed for 12 patients with concurrent HHV-6 and HHV-7 antibody responses after transplantation with a liver from a living relative by using an immunofluorescence assay (IFA). A neutralizing antibody titer assay (NT) and an immunoblot assay (IB) designed to detect immunoglobulin M (IgM) antibody to the HHV-6 immunodominant 101-kDa protein were compared in the diagnosis of an active HHV-6 infection. A total of 9 of 12 patients demonstrated concurrent HHV-6 and HHV-7 antibody responses, including increased IgG titers and/or the presence of IgM by IFA, and were thus analyzed for cross-reactive antibody to heterologous virus. The average percentages of residual antibody to HHV-6 and HHV-7 after absorption with HHV-6 antigen were 32.6% (range, 6 to 50%) and 55.6% (range, 35 to 100%), respectively. All 12 patients were subsequently analyzed for HHV-6 antibody by using IB and NT. IB detected IgM antibody to the 101-kDa protein in 75% (9 of 12) of the recipients. A significant rise in the NT antibody titer was detected in the same nine samples. However, HHV-6 DNA was detected by PCR in only five of nine plasma samples collected from recipients with a specific serologic response against HHV-6.