A follow-up study of children with neonatal herpes simplex virus infections with particular regard to late nervous disturbances

Beyond TORCH: A narrative review of the impact of antenatal and perinatal infections on the risk of disability

Infections and inflammation during pregnancy or early life can alter child neurodevelopment and increase the risk for structural brain abnormalities and mental health disorders. There is strong evidence that TORCH infections (i.e., Treponema pallidum, Toxoplasma gondii, rubella virus, cytomegalovirus, herpes virus) alter fetal neurodevelopment across multiple developmental domains and contribute to motor and cognitive disabilities. However, the impact of a broader range of viral and bacterial infections on fetal development and disability is less well understood. We performed a literature review of human studies to identify gaps in the link between maternal infections, inflammation, and several neurodevelopmental domains. We found strong and moderate evidence respectively for a higher risk of motor and cognitive delays and disabilities in offspring exposed to a range of non-TORCH pathogens during fetal life. In contrast, there is little evidence for an increased risk of language and sensory disabilities. While guidelines for TORCH infection prevention during pregnancy are common, further consideration for prevention of non-TORCH infections during pregnancy for fetal neuroprotection may be warranted.

Early Discontinuation of Phenobarbital After Acute Symptomatic Neonatal Seizures in the Term Newborn

Acute symptomatic seizures in the term newborn are often seen after perinatal brain injury. Common etiologies include hypoxic-ischemic encephalopathy, ischemic stroke, intracranial hemorrhage, metabolic derangements, and intracranial infections. Neonatal seizures are often treated with phenobarbital, which may cause sedation and may have significant long-term effects on brain development. Recent literature has suggested that phenobarbital may be safely discontinued in some patients before discharge from the neonatal intensive care unit. Optimizing a strategy for selective early phenobarbital discontinuation would be of great value. In this study, we present a unified framework for phenobarbital discontinuation after resolution of acute symptomatic seizures in the setting of brain injury of the newborn.

No footprint too small: case of intrauterine herpes simplex virus infection

Objectives

To describe the case of a preterm infant with intrauterine HSV infection. To discuss the epidemiology, features and complications associated with intrauterine HSV infection by conducting a review of medical literature.

Case presentation

A preterm male infant was born with diffuse skin erosions in various stages of healing suggestive of denuded bullae. Prenatal ultrasound showed evolving fetal cerebral ventriculomegaly, suspected Dandy-Walker malformation, and oligohydramnios. Neonatal skin swabs were positive for herpes simplex virus type 2 by polymerase chain reaction and the patient was treated with intravenous acyclovir from birth. Cranial ultrasound and magnetic resonance imaging findings showed severe progressive ex-vacuo ventricular dilatation consistent with intrauterine herpes simplex infection. Due to those findings and progressive multi-organ dysfunction, care was redirected to a palliative path and the child expired at 21 days of age. In retrospect, the mother had a few atypical vesicles on the left hand 4–5 weeks prior to delivery with a presumptive diagnosis of pompholyx.

Conclusions

Although confirmed intrauterine herpes simplex virus (HSV) infections are very rare, the potentially devastating prognosis and complications as evidenced by our case show that awareness of intrauterine HSV is critical for pediatricians as well as physicians involved in antenatal care. In order to adequately assess, treat and counsel pregnant women, more work is required to detect HSV infection, evaluate possible congenital infection and improve outcomes with fetal and neonatal treatment.

Vaccines for Perinatal and Congenital Infections-How Close Are We?

Congenital and perinatal infections are transmitted from mother to infant during pregnancy across the placenta or during delivery. These infections not only cause pregnancy complications and still birth, but also result in an array of pediatric morbidities caused by physical deformities, neurodevelopmental delays, and impaired vision, mobility and hearing. Due to the burden of these conditions, congenital and perinatal infections may result in lifelong disability and profoundly impact an individual's ability to live to their fullest capacity. While there are vaccines to prevent congenital and perinatal rubella, varicella, and hepatitis B infections, many more are currently in development at various stages of progress. The spectrum of our efforts to understand and address these infections includes observational studies of natural history of disease, epidemiological evaluation of risk factors, immunogen design, preclinical research of protective immunity in animal models, and evaluation of promising candidates in vaccine trials. In this review we summarize this progress in vaccine development research for Cytomegalovirus, Group B Streptococcus, Herpes simplex virus, Human Immunodeficiency Virus, Toxoplasma, Syphilis, and Zika virus congenital and perinatal infections. We then synthesize this evidence to examine how close we are to developing a vaccine for these infections, and highlight areas where research is still needed.

Management and results of epilepsy surgery associated with acyclovir prophylaxis in four pediatric patients with drug-resistant epilepsy due to herpetic encephalitis and review of the literature

PURPOSE

Herpes simplex virus encephalitis (HSE) is the most common cause of sporadic viral encephalitis in children and is responsible for epilepsy in approximately half of patients. In addition to medical treatment, epilepsy surgery may be offered to drug-resistant patients but carries a high risk of relapse of herpetic encephalitis. We are reporting our series of patients operated on between 2000 and 2019 with the systematic administration of acyclovir (ACV).

RESULTS

Four pediatric patients aged 4.5-12.8 years with drug-resistant epilepsy post-HSE underwent a tailored focal resection following invasive recordings (three patients) and a complete callosotomy (one patient). The total number of the surgical procedures for the four patients was eight, and a systematic administration of ACV as a prophylactic treatment of herpetic encephalitis relapse was done at each step. No patients had a relapse and the ACV was well-tolerated in all the cases. Following surgery two patients are seizure free, the patient who underwent callosotomy is Engel 3 and the fourth patient, in whom a large epileptic zone has contraindicated a second surgery, is Engel 4.

CONCLUSIONS

Our series demonstrated the dramatic efficacy of systematic ACV prophylaxis during all cranial surgeries. Moreover, our results on epilepsy, together with those of the literature, encourage more consideration regarding epilepsy surgery in this specific etiology. All types of surgical procedures (curative or palliative) can be offered to the patients, but in the case of focal surgery, due to the poor anatomical limits, invasive recordings are highly recommended.

Maternal immunization confers protection against neonatal herpes simplex mortality and behavioral morbidity

Neonatal herpes simplex virus (nHSV) infections cause devastating morbidity and mortality in infants. Most nHSV cases are associated with primary maternal infection, consistent with the hypothesis that maternal immunity is protective. In humans, we found HSV-specific neutralizing antibodies in newborns of immune mothers, indicating that placentally transferred HSV-specific antibody is protective. Using a murine model, we showed that passive administration of HSV-specific antibody to dams prevented disseminated infection and mortality in pups. Maternal immunization with an HSV-2 replication-defective vaccine candidate, dl5-29, led to transfer of HSV-specific antibodies into neonatal circulation that protected against nHSV neurological disease and death. Furthermore, we observed considerable anxiety-like behavior in adult mice that had been infected with low doses of HSV as neonates, despite a notable lack of signs of infection. This phenotype suggests that nHSV infection can have an unsuspected and permanent impact on behavior. These behavioral sequelae of nHSV were prevented by maternal immunization with dl5-29, demonstrating an unexpected benefit of immunization. These findings also support the general concept that maternal immunization can prevent neurotropic neonatal infections and associated morbidity and mortality.

Outcomes beyond hospital discharge in infants and children with viral meningitis: A systematic review

Viruses are the commonest cause of childhood meningitis, but outcomes beyond hospital discharge are poorly described. We undertook a systematic literature review of long-term outcomes following paediatric viral meningitis. A search was carried out using MEDLINE, Embase, and Cochrane Review for studies from 1 January 1990 to 31 December 2018. Studies were included where specific outcome measures were available beyond hospital discharge for children <16 years old with viral meningitis. In total, 3588 papers were identified of which 14 were eligible for inclusion. Four studies reported outcomes in children with nonenterovirus 71 meningitis. A US study of 16 cases demonstrated subtle language difficulties at 3-year follow-up in infants in contrast to an Australian study, which revealed no impairment in language. A Fijian study showed that two out of eight cases had sensorineural hearing loss compared with none in a UK cohort of 668 infants. Three studies evaluated outcomes of enterovirus 71 meningitis in China and Taiwan, two showed cases recovered without sequelae, while one demonstrated an increased risk of attention deficit hyperactivity disorder. Two studies including 141 cases of human parechovirus revealed no evidence of neurodevelopmental sequelae. Conversely, an Australian study demonstrated neurodevelopmental sequelae in 11 out of 77 infants with parechovirus meningitis. Most studies identified in this review demonstrated a high proportion of good clinical outcomes following viral meningitis. However, the data are limited, so robustly conducted neurodevelopmental studies are warranted to inform the evidence-based management of viral meningitis beyond hospital discharge.

Research Recruitment of Adult Survivors of Neonatal Infections: Is There a Role for Parental Consent?

Research on competent adult subjects does not require the consent of anyone beyond that of the adult subject. This case is complicated, however, because the targeted subjects were initially enrolled by their parents in a neonatal study and because the focus of the study, genital herpes simplex virus (HSV), carries significant stigma in the community. In considering the ethical issue of directly approaching the young adults for participation in this research, there are three key themes that need to be evaluated and considered: 1) the importance of the research for anticipatory guidance about the long-term impact of neonatal HSV; 2) the concerns of parents in disclosing the diagnosis; and 3) the interests of affected teens/young adults and their future partners.

Diagnostics for Herpes Simplex Virus

Herpes simplex virus (HSV) is one of the most common, yet frequently overlooked, sexually transmitted infections. Since the type of HSV infection affects prognosis and subsequent counseling, type-specific testing to distinguish HSV-1 from HSV-2 is recommended. Although PCR has been the diagnostic standard for HSV infections of the central nervous system, until now viral culture has been the test of choice for HSV genital infection. However, HSV PCR, with its consistently and substantially higher rate of HSV detection, will likely replace viral culture as the gold standard for the diagnosis of genital herpes in people with active mucocutaneous lesions, regardless of anatomic location or viral type. Alternatively, type-specific serologic tests based on glycoprotein G should be the test of choice to establish the diagnosis of HSV infection when no active lesion is present. Given the difficulty in making the clinical diagnosis of HSV, the growing worldwide prevalence of genital herpes and the availability of effective antiviral therapy, there is an increased demand for rapid, accurate laboratory diagnosis of patients with HSV.

Neonatal herpes simplex virus infection

Herpes simplex virus (HSV) infection in the neonate is a rare event with severe consequences for the child even if adequately treated with antiviral drugs. Mothers with primary genital herpes infections late in pregnancy or at delivery have a high risk of transferring the infection to the child, while the risk of transfer in mothers with recurrent genital infections is only a few percent. Neonatal herpes localized in skin-eye-mouth has no mortality and morbidity after antiviral treatment. In neonatal disseminated and central nervous system disease, early treatment is a predictor for better outcome. The morbidity in survivors is high; after herpes encephalitis, only one-third of children have normal development. While awaiting vaccines or reliable predictors for prevention of neonatal herpes, clinical awareness of primary maternal herpes during pregnancy and recommendations for prophylactic treatment are important tools. For pediatricians the differential diagnosis of a child aged two to four weeks with seizures, neonatal herpes encephalitis must be considered and either excluded or treated. Neurological follow-up and training programs to minimize the consequences of a disability are important clinical aspects.

Neuropsychologic outcomes in children with neonatal herpes encephalitis

Neonatal herpes simplex virus infection with involvement of the central nervous system is a serious disease with high morbidity, even with acyclovir therapy. The disability includes cerebral palsy and different aspects of cognitive dysfunction which are of utmost importance for the child's future habilitation. We conducted a descriptive cohort study to define neuropsychologic outcomes and determine the relationship between neonatal neuroimaging and neuropsychologic outcomes. Among 267,690 children born in the Stockholm area over 12 years (1989-2000), 14 were diagnosed with neonatal herpes including central nervous system involvement. Nine children were neuropsychologically evaluated. Neonatal herpes virus infection had an even greater impact on cognitive function, speech ability, and attention deficit than anticipated. Relapse leading to deterioration was demonstrated in one child. Social skills were influenced to a lesser degree. Neurodevelopmental outcomes of the children were not well-correlated with extent of cerebral damage as visualized by computed tomography at 7-28 days after onset of signs. Neuropsychologic assessment is essential in the habilitation of the child, and a prerequisite for the evaluation of new treatments and for the assessment of deterioration of cerebral function related to relapses.

Improved neurodevelopmental outcomes following long-term high-dose oral acyclovir therapy in infants with central nervous system and disseminated herpes simplex disease

OBJECTIVE

Infants with neonatal herpes, classified as central nervous system or disseminated disease, have a high incidence of moderate and severe neurologic deficits despite standard acute therapy.

STUDY DESIGN

Following completion of parenteral therapy, infants with central nervous system and/or disseminated disease received 2 years of continuous oral acyclovir therapy. Target minimum peak serum acyclovir concentrations were >2 microg/ml for the first three patients, and >3 microg/ml for the subsequent 13 patients. Safety assessments were made every 3 months. We evaluated neurodevelopmental outcomes with Bayley Scales of Infant Development.

RESULTS

A total of 16 consecutive herpes simplex virus-infected infants born during 1990 to 2003 received the treatment plan; 13/16 infants had central nervous system disease; 3 had disseminated disease without central nervous system involvement. A total of 69% (11/16) had Bayley scores in the normal range for mental development and 79% (11/14) had motor scores in the normal range. At the final assessment, five children had developmental delays. One child had severe mental delay with normal motor development. Four children had mild mental delays, with severe motor delays in three. All children were independently mobile, without seizure disorder, had normal vision, and had speech development. During the 2-year course of treatment, five children had brief recurrences of dermal lesions, and none had evidence of neurologic deterioration. There were no serious or sustained adverse drug reactions.

CONCLUSION

This pilot study reports improved outcomes in a small cohort of infants with a prolonged course of oral acyclovir. A minority of these children exhibited mild or significant developmental delays. Further investigation of this approach to treatment is warranted.

Relapse of neonatal herpes simplex virus infection

BACKGROUND

Neonatal herpes simplex virus (HSV) infection is a severe disease with high mortality and morbidity. Recurrence of skin vesicles is common.

OBJECTIVE

To determine the features of relapse and identify the factors related to relapse.

DESIGN

Thirty two surviving patients with neonatal herpes virus infections were enrolled. All patients received acyclovir treatment. Clinical and virological data were analysed and compared between relapsed and non-relapsed cases.

RESULTS

Thirteen (41%) had either local skin or central nervous system relapse between 4 and 63 days after completing the initial antiviral treatment. Nine patients exhibited local skin relapses, and four developed central nervous system relapses. In one skin and two central nervous system relapse cases, neurological impairment later developed. Type 2 virus infection was significantly related to relapse (odds ratio 10.4, 95% confidence interval 1.1 to 99.0). Patients with relapse had worse outcomes than those without relapse.

CONCLUSION

Neonates with HSV type 2 infections have a greater risk of relapse. Relapsed patients have poorer prognoses.

Detection of herpes simplex virus DNA in dried blood spots making a retrospective diagnosis possible

BACKGROUND

Herpes simplex virus (HSV) infections in neonates are associated with life-threatening disease. Early diagnosis and treatment with antiviral therapy has decreased the morbidity, mortality and long-term sequelae in surviving children. The aim of the study was to investigate if herpes simplex virus DNA detection in dried blood spots on filter papers (Guthrie cards) sampled for screening of metabolic diseases may contribute to early diagnosis of neonatal HSV infection and enable pre-emptive therapy.

METHODS

For detection of HSV-1 and -2 DNA, two different DNA extraction methods were evaluated. A minimal essential medium (MEM) extraction method was found superior and was used in combination with detection of HSV-1 and -2 DNA by PCR in dried blood spots from children with verified neonatal HSV infection. Cards from 28 children were included. The onset of illness varied from day 0 to 42 days and was the result of different types of maternal infection (27 cases) and an external source (one case).

RESULTS

HSV DNA was detected in seven of the 28 Guthrie cards, two were HSV-1 and five were HSV-2 DNA positive. Positive dried blood spot cards were sampled within the interval 5 days before, to 6 days after onset of neonatal herpes. In cases of late onset CNS disease, viremia, was not demonstrable at the age of 3-5 days, the time period when the blood spot cards are normally sampled.

CONCLUSION

Viremia, the prerequisite for demonstrating HSV DNA in dried blood spot cards preceded the onset of illness by up to 5 days and lasted at least up to 6 days thereafter. Analysis of HSV DNA in dried blood spot cards may be of value in the diagnostic arsenal for early onset of neonatal herpes and also have a role in the follow up of a child exposed at delivery. As the majority of the later onset neonatal herpes encephalitis cases are missed, a large-scale neonatal screening does not seem appropriate.

Neonatal herpes simplex virus infections: HSV DNA in cerebrospinal fluid and serum

AIM

To investigate the diagnostic potential of herpes simplex virus (HSV) DNA in cerebrospinal fluid and serum; to correlate the findings with outcome in the child and with type of maternal infection.

METHODS

Cerebrospinal fluid and serum specimens from 36 children with verified neonatal HSV infections, diagnosed between 1973 and 1996, were examined using the polymerase chain reaction technique (PCR).

RESULTS

In 21 children for whom both cerebrospinal fluid and sera were available, HSV DNA was found in one or both specimens in 19 (90%). Overall, HSV DNA was found in the cerebrospinal fluid of 74% of 27 children, and in the sera of 20 out of 30 children (67%). In two children HSV DNA was not demonstrable in either serum or cerebrospinal fluid. In sequential specimens from four children, the persistence of HSV DNA after the end of intravenous treatment was associated with a poor prognosis.

CONCLUSIONS

These findings indicate that HSV DNA detection in CSF and serum is highly sensitive for the diagnosis of neonatal HSV infections but does not replace the detection of virus in other locations using virus isolation and antigen detection.

Reactivation of herpes virus after surgery for epilepsy in a pediatric patient with mesial temporal sclerosis: case report

OBJECTIVE

This case report is presented to raise the awareness of the potential risk of reactivation of herpes simplex virus (HSV) encephalitis after intracranial surgery.

CLINICAL PRESENTATION

The case of an 8-year-old male patient who suffered a reactivation of HSV encephalitis after undergoing amygdalohippocampectomy for complex partial seizures is reported. This patient had previously contracted HSV 1 meningoencephalitis at the age of 16 months. Six years later, a left amygdalohippocampectomy was proposed after the development of intractable partial epilepsy associated with left mesial temporal lesions. During the postoperative period, the patient suffered severe clinical deterioration with partial status epilepticus, aphasia, and hyperthermia, which resolved after intensive antiepileptic treatment supported by acyclovir.

CONCLUSION

We advise prophylactic pre-, peri-, and postoperative treatment with acyclovir for patients with known histories of HSV encephalitis who undergo intracranial procedures.

HSV-1 and HSV-2 in herpes simplex encephalitis: a study of sixty-four cases in the United Kingdom

The incidence of herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) in herpes simplex encephalitis (HSE) was investigated using cerebrospinal fluid (CSF) samples from sixty-four cases of HSE. A polymerase chain reaction (PCR) employing primers flanking a region of the HSV thymidine kinase gene common to both HSV-1 and HSV-2 was used to detect HSV in the CSF. HSV-1 and HSV-2 were differentiated by digestion with restriction enzymes. Two enzymes were employed; Aval which cleaved only the HSV-2 gene product and Avall which cleaved only the HSV-1 gene product. Sixty-three cases of HSE were found to be due to HSV-1; one case due to HSV-2. These data confirm previous observations that HSV-2 is a rare cause of post-neonatal herpes encephalitis but indicates that a PCR procedure capable of detection of both viruses is essential for efficient diagnosis of HSE.

Hydrocephalus induction in mice infected with herpes simplex virus type 2 after antiviral treatment

By using antiviral chemotherapy to moderate the lethal effect of wild-type herpes simplex virus type 2 (HSV-2), a new mouse model for herpes simplex virus (HSV)-induced hydrocephalus was developed. Groups of BALB/c mice were infected either intracerebrally (i.c.) or intraperitoneally (i.p.) with a lethal dose of HSV-2. The antiviral agent 2'-fluoro-5-methylarabinosyluracil (FMAU) was administered i.p. 2 days after virus inoculation. By day 21, 80 and 71.4% of the mice infected i.c. or i.p., respectively, survived. The surviving animals were randomly subdivided into different groups and some were challenged i.c. or i.p. with a lethal or superlethal dose of homologous virus. The mice were sacrificed at 2 or 3 months after the initial virus infection. Neuropathological changes of the brains were assessed. Dilation of lateral and third ventricles was noted in the animals initially inoculated i.c., especially in all the animals inoculated i.c. and challenged i.c. with a superlethal virus inoculum, but not in those inoculated i.p. Microscopic examination of hydrocephalic brains revealed evidence of viral meningoencephalitis. Two different mechanisms of ventricular enlargement in this animal model are proposed. This model is relevant since HSV-induced cases of hydrocephalus have been reported to occur in humans and in particular neonates. Issues of virus persistence and expression, long-term evaluation for disease progression, and intervention strategies could be examined with this model.

Neonatal herpes simplex: clinical findings and outcome in relation to type of maternal infection

In 39 mothers of children with neonatal herpes simplex virus infection, maternal infection was serologically characterized retrospectively and was related to maternal clinical symptoms and to the clinical findings and outcome in the child. Thirteen mothers had a primary infection (six type 1, seven type 2), mostly with clinical symptoms. The mean age of onset of the disease of the infants was 7 days and a disseminated disease was most commonly found. Most of the type 1-infected children recovered completely, whereas all but one of the type 2-infected children died. Twenty mothers had a recurrent (2 type 1, 18 type 2) and 4 an intermediate infection (primary type 2, prior infection with type 1), mostly asymptomatic. Their children had a localized disease (of the skin-eye-mouth or the central nervous system) with onset at a mean age of 14 or 13 days, respectively. The frequency of neurological sequelae was high. Two mothers had no serological signs of herpes infection.

Dosing considerations for oral acyclovir following neonatal herpes disease

Herpes simplex virus lesions recur in 8-30% of infants who receive a course of parenteral antiviral therapy for an initial infection. Long-term acyclovir is used by some clinicians to prevent recurrent Herpes simplex disease. We describe nine infants who were treated with doses of oral acyclovir which were chosen to achieve 2-h post-plasma concentrations of > or = 2 micrograms/ml. Eight infants had Herpes simplex encephalitis and one had multiple recurrences of dermal and ocular disease. The target plasma concentration was chosen in order to attain acyclovir cerebrospinal fluid distribution (< or = 50% plasma) for an estimated ID30 of Herpes simplex II strains of 0.1-0.5 microgram/ml. One of nine patients failed to achieve the target plasma acyclovir concentration. One of nine patients developed symptomatic recurrence of the central nervous system disease and none of the remaining eight patients experienced recognized dermal or neurologic recurrence of Herpes simplex disease. Renal and neurologic status were routinely monitored and no signs of acyclovir toxicity were observed. Plasma concentration of acyclovir > or = 2 micrograms/ml may be achieved with average oral doses of 1340 mg/m2/dose (1000-1740 mg/m2/dose) given at 12-h intervals.

Acute retinal necrosis caused by reactivation of herpes simplex virus type 2

Acute retinal necrosis is a severe form of necrotizing retinitis. Acute retinal necrosis has been demonstrated to be caused by varicella-zoster virus and herpes simplex virus type 1. We treated three patients with acute retinal necrosis apparently caused by recrudescence of latent herpes simplex virus type 2. Primary viral infection was probably congenital, with documented perinatal herpes simplex virus type 2 infection in two patients. Bilateral chorioretinal scars were present in two patients, neither of whom had a history of ocular herpetic infection, suggesting that earlier subclinical chorioretinitis had occurred. In each case, periocular trauma preceded the development of retinitis by two to three weeks. These cases are evidently caused by trauma-induced reactivation of latent virus rather than the onset of a primary infection.

Autopsy findings in two cases of neonatal herpes simplex virus infection: detection of virus by immunohistochemistry, in situ hybridization and the polymerase chain reaction

We describe the pathological findings in two fatal cases of neonatal infection with herpes simplex virus. One had an encephalitis caused by herpes simplex virus type 2 (HSV-2); the other had a disseminated infection with herpes simplex virus type 1 (HSV-1). Confirmation of the diagnosis was obtained by use of the polymerase chain reaction to amplify viral DNA from paraffin sections of autopsy tissues. By using primers which amplify fragments of the HSV-1 thymidine kinase gene and HSV-2 glycoprotein gene respectively it was possible to discriminate between infection with HSV-1 and HSV-2. In contrast, immunohistochemistry and in situ hybridization using commercially available reagents did not distinguish between HSV-1 and HSV-2 infection. However, immunohistochemistry and in situ hybridization are probably more reliable than the polymerase chain reaction for assessment of the distribution of virus in different tissues.

In situ polymerase chain reaction: localization of HSV-2 DNA sequences in infections of the nervous system

To detect and localize a herpes simplex virus type 2 (HSV-2) thymidine kinase gene sequence in paraffin sections of brains and trigeminal ganglia of infected mice, an in situ polymerase chain reaction (ISPCR) protocol was developed. Using a single pair of primers, a 110 base pair DNA target sequence, and incorporation of a digoxigenin-labelled nucleotide during amplification, this procedure permitted rapid, specific, reproducible detection of infected cells. During acute brain infection, cells labelled by ISPCR were in the same infected foci that, in adjacent sections, contained viral antigen. This, together with controls, gave evidence of method specificity. In mice surviving acute infection, latently infected cells were labelled by ISPCR. In brains, focal areas contained labelled cell nuclei, and in trigeminal ganglia, neuronal nuclei were likewise labelled. Latent infection was confirmed by several methods, including identification of an HSV-specific sequence in DNA extracts of brains and ganglia, virus isolation from explanted ganglia, and HSV-2 latency-associated transcript (LAT) RNA localization in ganglionic neurons by in situ hybridization. Evidence in brains of ISPCR-labelled cells in regions where HSV-2 LAT-positive cells were not detected, and in ganglia of more ISPCR-labelled neurons than were LAT-positive, indicated that ISPCR is more sensitive in detecting latently infected cells than previous methods.

Detection of viral DNA in neonatal herpes encephalitis autopsy tissues by solution-phase PCR: comparison with pathology and immunohistochemistry

To detect DNA sequences of herpes simplex virus (HSV) in neural and non-neural tissue sections in disseminated human neonatal HSV infection, a solution polymerase chain reaction (PCR) protocol was developed which amplified HSV thymidine kinase and host genomic DNA sequences that were hybridized with sequence-specific probes in Southern blots. Serial sections of formalin-fixed, paraffin embedded autopsy tissues were tested by PCR and compared to histology and HSV antigen detection. The sensitivity, specificity and reproducibility of this PCR protocol were determined on uninfected and HSV-infected mouse tissues and on HSV DNA from infected tissue culture cells. Samples estimated to contain as few as 60 copies of preserved HSV DNA target sequence gave a positive PCR result. In nine neonates that died during acute HSV infection, all non-neural tissues and a minority of neural tissues with histological lesions had HSV antigen; when DNA could be amplified, HSV DNA sequences were detected by PCR. Together, these findings indicate a direct role for virus in the pathogenesis of these lesions. In the same cases, some or all brain samples were negative for HSV antigen, but nevertheless had HSV DNA sequences detected by PCR. The possible explanations for this finding are discussed. In one neonate dying seven weeks after birth, HSV sequences were found in brain lesions in the absence of HSV antigen; neither HSV DNA nor antigen were found in non-neural tissues, suggesting a latent HSV infection in brain. It is practical to apply PCR methods to detect minute quantities of viral DNA in formalin-fixed, paraffin embedded autopsy tissues.(ABSTRACT TRUNCATED AT 250 WORDS)