Wait times for paediatric rehabilitation

BACKGROUND

Early therapy intervention for children with disabilities may improve functional outcomes. Access to paediatric rehabilitation services can sometimes be difficult.

OBJECTIVES

To describe waiting time to receive physical therapy (PT) and occupational therapy (OT) services at rehabilitation centres for young children with physical disabilities; to examine factors associated with these waiting times.

DESIGN

Prospective cohort.

SUBJECTS

Two hundred and six children with physical disabilities, aged 6 to 72 months, referred in 2002-2004 from the Montreal Children's Hospital and Sainte-Justine Hospital to paediatric rehabilitation centres.

MEASURES

Data on date of referral, age, gender and diagnosis were obtained from the hospital databases. Data on date of first PT or OT appointments at the rehabilitation centre, family socio-demographics and disability severity (WeeFIM) were obtained during parental interviews.

RESULTS

Half of the sample waited more than 7 and 11 months for PT and OT services, respectively. Shorter waiting time was significantly associated with younger child's age and referral to one particular rehabilitation centre.

CONCLUSION

Children with physical disabilities experience long waiting times for PT and OT rehabilitation services. Strategies to improve timely service delivery are needed.

Communicating a diagnosis of cerebral palsy: caregiver satisfaction and stress

As part of the implementation of a population-based registry of children with cerebral palsy, caregiver satisfaction with the process by which diagnosis was originally communicated by a professional was assessed. Satisfaction with various aspects of the diagnosis process was assessed using a five-point Likert scale and related to child, family, and situational characteristics. Measures were then correlated with current caregiver stress as measured objectively by the Parenting Stress Inventory. During the registration process, 59 consecutive caregivers (55 mothers) were questioned. Overall, 62% (35/59) were satisfied with the disclosure process, with satisfaction ranging from 69% (41/59-hopefulness) to 92% (54/59-honesty) for professional qualities, and from 61% (36/59-sufficient information provided) to 78% (46/59-understandable) for disclosure content. Satisfaction was related to the quantity and content of information given at the disclosure session. Parenting Stress Inventory scores, both total and for parental distress, correlated significantly with both the severity of the child's cerebral palsy and caregiver satisfaction with varying elements of the disclosure process. Overall caregiver satisfaction with the process by which a diagnosis of cerebral palsy is given appears to be good. Together with the severity of a child's intrinsic cerebral palsy, it appears to relate to later parental adjustment to a setting of chronic disability, suggesting a portal through which improvements in information delivery may result in better familial adaptation to disability.

When and by Whom Is Concern First Expressed for Children With Neuromotor Problems?

OBJECTIVE

To describe when and by whom concern is first expressed for children referred to rehabilitation because of neuromotor problems.

STUDY DESIGN AND SETTING

We conducted a survey of parents of 92 children (aged 0-6 years) who were on the waiting list for physical or occupational therapy services at rehabilitation centers in Montréal, Québec. We compared age of child at initial concern with who first expressed concern for children who were considered at risk due to their perinatal history of prematurity and those who were not born prematurely but were later diagnosed as having neuromotor problems.

INTERVENTION

Parents were interviewed regarding their child's medical history and utilization of health care services.

RESULTS

Parents were concerned later than physicians were regarding their child's development (mean difference, 8.2 months; 95% confidence interval [CI], 3.7-12.6 months). There was no significant difference in time of recognition of problems between the premature (10.2 months) and full-term (11.9 months) groups. Even after controlling for risk group, parental concern occurred later than physician concern (beta coefficient, 7.3; 95% CI, 2.5-12.2). The child's age at the time of initial concern was associated with the child's age at referral to rehabilitation (beta coefficient, 0.04; 95% CI, 0.01-0.06).

CONCLUSIONS

Early recognition is important if a child is to benefit from early rehabilitation. It may be important to improve primary care screening of children for neuromotor problems and to increase parental awareness regarding normal motor development of their children. Prompt, simultaneous referral to medical evaluation and rehabilitation resources may decrease delays in rehabilitation.

The relationship between an aortic isthmus blood flow velocity index and the postnatal neurodevelopmental status of fetuses with placental circulatory insufficiency

OBJECTIVE

The purpose of this study was to evaluate the association between an abnormal aortic isthmus blood flow index and postnatal neurodevelopmental outcome in fetuses with placental circulatory insufficiency. STUDY DESIGN Forty-eight children who were born between 1991 and 1999 were included in this study on the basis of abnormal umbilical artery Doppler velocimetry. Prenatal isthmus blood flow index was obtained by dividing the sum of the systolic and diastolic Doppler blood flow velocity integrals by the systolic blood flow integrals. Neurodevelopmental outcome between 2 and 5 years was classified as optimal, when neurologic assessment and developmental quotient were within normal limits and as nonoptimal when abnormal neurologic findings and/or a nonoptimal developmental quotient was present. Neurodevelopmental outcome was analyzed in relation to isthmus flow index and pulsatility indices in the umbilical artery.

RESULTS

The mean gestational age at delivery was 33.0 +/- 2 weeks. Nonoptimal neurodevelopmental outcome was found in 60.4% of the children (29/48). An inverse correlation was found between the isthmus blood flow index and postnatal neurodevelopmental outcome. All 13 children with an isthmus blood flow index of <0.5 were in the nonoptimal group. All 19 children with an optimal outcome had an isthmus blood flow index of >0.5, but this was also the case for 16 other children with nonoptimal neurodevelopmental outcome. An isthmus blood flow index cut-off value of 0.70 was associated with the highest overall positive and negative predictive values. The pulsatility index in the umbilical artery did not provide any significant contribution in the explanation of the outcome.

CONCLUSION

The isthmic blood flow index can help to identify a subgroup of fetuses with placental circulatory insufficiency that might benefit from early delivery.

The Amiel-Tison neurological assessment at term: Conceptual and methodological continuity in the course of follow-up

The Amiel-Tison Neurological Assessment at Term (ATNAT) is part of a set of three different instruments based on a neuro-maturative framework. By sharing a same methodology and a similar scoring system, the use of these three assessments prevents any rupture in the course of high risk children follow-up from 32 weeks post-conception to 6 years of age. The ATNAT which takes 5 minutes to administer may be used in clinical setting as well as in research. Clustering of severe to mild neuro-cranial signs in the neonatal period permits identification of children who could benefit from early intervention.

Syndrome de délétion 22q11 et maladie de Basedow. À propos de trois observations pédiatriques

Hypothyroidism is a well recognized complication of 22q11.2 deletion syndrome. Auto-immune hyperthyroidism is less common. We report three patients with a 22q11.2 deletion and Graves' disease diagnosed at age 17, 14 and 11 years, respectively. The clinical and biological presentation was typical for auto-immune hyperthyroidism. Graves' disease should be periodically sought during the follow-up program of patients with 22q11.2 deletion syndrome.

Influence of the state of alertness on the pattern visual evoked potentials (PVEP) in very young infant

The aim of the study was to evaluate the pattern visual evoked potentials (PVEP) combined with an optimal state of vigilance, called liberated state (LS), in order to improve testing in very young infants. Transient PVEP were recorded in response to a checkerboard pattern of 120, 60 and 30 min of arc. in 56 fullterm newborns and 79 preterm infants from birth to 4 months of age. In the fullterms, 28 infants in each group were tested in LS or spontaneous alertness (SA) while in the preterms, 48 infants in each group were tested in LS or SA. No significant difference was found in the amplitude and/or peak time of the PVEP responses between subjects tested in LS compared to SA groups. However, the LS condition improved by approximately 25% the feasibility of prolonged PVEP testing in preterms aged less than 2 months (corrected age). This suggest that the LS condition enhances the clinical feasibility of PVEP testing in very young infants and should be used to optimize the evaluation of visual development in high risk infants in this age group.

Interobserver reliability of the Amiel-Tison neurological assessment at term

The eligibility criteria currently used for neurodevelopmental follow-up are traditionally based on perinatal events and characteristics of the infants at birth. However, they seem unsatisfactory to target efficiently all children who will manifest long-term neurologic sequelae and eventually require rehabilitation services. The updated version of the Amiel-Tison's Neurological Assessment At Term (ATNAAT) is expected to allow a better prediction of the neurodevelopmental outcome in high-risk infants. The main objective of the present study, which was performed on 35 infants, was to analyze the interobserver reliability of the updated version of ATNAAT. The evaluator and the observer coded the items of the test simultaneously. Among the 35 items tested, 16 demonstrated an excellent reliability based on the kappa coefficient, 11 items yielded a fair to good reliability, whereas only two items produced an agreement below 0.40. The final synthesis, which was a global appreciation of the neurologic status based on the different findings, yielded a good reliability with a kappa coefficient of 0.76. Among the infants who had a nonoptimal outcome from the assessment, only 38.5% met the traditional criteria currently used for follow-up. It would be important to conduct further research on predictive validity to demonstrate the capacity of the ATNAAT to forecast the long-term neurologic outcome of infants at risk.

Réseau de suivi des nouveau-nés à risque de développer un handicap : l’exemple du réseau « Grandir ensemble en Pays-de-la-Loire »

Newborns are given attentive perinatal care but the organization of further follow-up can be haphazard. The main consequences are the difficulties parents have in finding appropriate medical assistance for caring for high-risk infants and the absence of appropriate surveillance or efficient care. An inpatient-outpatient healthcare network enables early care of these infants and can reduce the consequences of neurosensorial sequelae. The overall impact of the regional perinatal care can also be evaluated. Such a network has been implemented in the Pays de Loire region in France since early 2003. In six months, among 1000 initially included infants, 500 were followed by pediatricians working in an outpatient (40%) or inpatient (60%) setting. This organization enables correction of over-centralization of neonatal care and the absence of coordination for follow up.

Reference values for an index of fetal aortic isthmus blood flow during the second half of pregnancy

OBJECTIVE

During fetal life, the parallel position of the two cardiac ventricles confers a special status to the aortic isthmus. Flow through the isthmus reflects the balance between the performances of the two ventricles and their respective peripheral impedances. This study proposes a fetal aortic isthmus flow velocity index and its reference values defined on the basis of gestational age (GA).

METHODS

Video recordings of 111 normal fetuses from 18 to 39 weeks of gestation were retrospectively reviewed. An isthmus flow velocity index (IFI) was calculated as follows: IFI = (systolic + diastolic)/systolic velocity integrals. GA-specific reference ranges of IFI were constructed.

RESULTS

An IFI of 1.33 +/- 0.03 was found at 18 weeks. This value decreased slightly but steadily with GA to reach 1.23 +/- 0.16 at 39 weeks. This change is mainly related to a decrease in diastolic velocity integrals.

CONCLUSION

The proposed IFI provides information on the direction and, indirectly, on the volume of blood flow through the fetal aortic isthmus.

Changes in flow velocity patterns of the superior and inferior venae cavae during placental circulatory insufficiency

OBJECTIVES

Placental circulatory insufficiency, expressed by the disappearance of the diastolic component of the umbilical artery Doppler velocity waveforms, causes blood flow redistribution that could disturb, to different extents, the systemic venous returns to the heart. The purpose of this study was to investigate the effect of an absence of diastolic blood flow in the umbilical artery on the relationship between the Doppler flow velocities of the venae cavae.

METHODS

Fifteen normal fetuses (normal group) were matched for gestational age with 11 fetuses with absent diastolic flow in the umbilical artery (abnormal group). In the venae cavae, the following Doppler variables were measured and compared between groups: (a) during ventricular systole: maximum (S(max)) and minimum velocities (S(min)) and velocity integrals (SI); (b) during ventricular diastole: peak velocity of the E-wave and its integral (EI), the A-wave and its integral (AI). A venous velocity index (VVI) was defined as (S(max) + S(min))/S(max).

RESULTS

In the normal group, S(min) and VVI were significantly higher in the inferior vena cava (IVC) than in the superior vena cava (SVC). The ratio SVC-VVI/IVC-VVI was therefore always less than one. In the abnormal group, S(min), SI, E, EI and VVI were higher in the SVC compared to those of the IVC. The ratio SVC-VVI/IVC-VVI was always greater than one.

CONCLUSION

In the absence of umbilical artery diastolic flow, a reciprocal shift is observed between the IVC and SVC velocity waveforms characterized by a flow profile in the IVC which resembles that of a normal SVC profile and vice versa. These changes are another manifestation of blood flow redistribution towards the brain in the presence of placental circulatory insufficiency. They should be taken into account on Doppler assessment of ventricular diastolic function based on venous flow patterns during placental circulatory impairment.

Minor neurological signs and developmental performance in high risk children at preschool age

The aim of this study was to establish correlations between minor neurological findings and developmental performance. A cohort of 72 preschool children was studied (38 females, 34 males; mean age 3 years 8 months, SD 1 year 2 months, range 2 to 5 years) who were considered to be at high risk due to placental insufficiency. The cohort was divided into four categories of neurological status: (1) minimal cerebral palsy (MCP) with independent walking before age 2 years; (2) Amiel-Tison triad (ATT) including imbalance of passive axial tone, phasic stretch reflex in triceps surae, and cranial signs, particularly on the squamous suture; (3) intermediate with one or two of the three ATT signs; and (4) absence of neurological findings. Six subscales of the Griffiths Mental Developmental Scales assessing locomotion, eye-hand coordination, interpersonal skills, language, performance, and practical reasoning were administered. Significant differences were found according to neurological status in three specific domains of development: coordination (F=2.84, p=0.04), language (F=3.65, p=0.02), and practical reasoning (F=3.62, p=0.02). In addition, significant differences were also found in language (L) and practical reasoning (R) performances according to the side of the abnormal stretch reflex: bilateral stretches (L=87.8; R=75.3) or an isolated right stretch (L=95.3; R=83.6) are more strongly associated with impaired developmental performances than an isolated left stretch (L=101.3; R=88.2) with F=2.94; p=0.04 for language and F=3.00, p=0.04 for practical reasoning. We concluded that a short neurological examination, easily performed by pediatricians and family practitioners, can identify permanent markers of minor brain damage occurring before, during, or soon after birth and so anticipate consequences.

Epstein-Barr virus primes human polymorphonuclear leucocytes for the biosynthesis of leukotriene B4

In the present study, we have investigated the effect of the short-term incubation of polymorphonuclear leucocytes (PMN) with infectious Epstein-Barr virus (EBV) on leukotriene B(4) (LTB(4)) biosynthesis. Pre-exposure of PMN to EBV led to an increased production of LTB(4) upon stimulation with either the ionophore A23187, the chemotactic peptide fMLP, or phagocytic particles (zymosan). Experiments performed with viral particles pretreated with a neutralizing antibody raised against the gp350 of the viral envelope revealed that a specific interaction between the PMN surface and the viral glycoprotein gp350 is required for the priming effect of EBV. Preincubation of PMN with EBV resulted in an increased release of arachidonic acid upon stimulation with a second agonist. Moreover, LTB(4) biosynthesis in EBV/A23187-treated PMN was greatly diminished in the presence of an inhibitor of the cytosolic phospholipase A2 (cPLA(2)), suggesting that cPLA(2) plays a critical role in the priming effect of EBV. Accordingly, EBV by itself promoted Ser-505 phosphorylation of cPLA(2) and strongly enhanced fMLP-induced phosphorylation of p38 MAP kinase, an enzyme known to phosphorylate cPLA(2) in human PMN. Furthermore, fMLP-induced translocation of cPLA(2) was strongly enhanced when PMN were previously exposed to EBV. These data indicate that binding of EBV to human PMN results in the activation of intracellular events involved in the release of pro-inflammatory lipid mediators.

[Investigation of fetal arrhythmias by simultaneous recording of ascending aortic and superior vena caval blood flow]

In a period of 18 consecutive months, all the foetus referred to our Foetal Cardiology Unit for investigation of arrhythmia were systematically assessed by M mode echocardiography and simultaneous recording of blood flow in the superior vena cava and the aorta (SVC/Ao). This study was undertaken to compare the performance of these two approaches. The foetus were classified into three groups according to the arrhythmia diagnosed: Group 1: irregular arrhythmias, Group 2: bradycardias, Group 3: tachycardias. A surface ECG was recorded in all the neonates in whom the arrhythmias persisted. In Group 1, including 50 cases of extrasystoles (49 atrial and 1 ventricular), M mode echo and the Doppler provided the diagnosis in 42 and 47 cases respectively. This difference was not statistically significant. Group 2 comprised four cases of bradycardia (2 blocked atrial bigeminy, 2 complete atrioventricular blocks); the two methods provided the diagnosis in all 4 cases. Group 3 comprised 11 cases including 7 supraventricular tachycardias (SVT), 2 flutter, 1 chaotic atrial rhythm and 1 ectopic junctional rhythm. Complete analysis of these arrhythmias was possible by M mode in 4 cases and by Doppler in all cases. This difference was significant. The distribution of the 7 cases of SVT with respect to the duration of the ventriculoatrial interval was possible by M mode in 2 cases and in all cases by Doppler. This was a decisive factor in the choice of antiarrhythmic therapy. The authors conclude that Doppler and M mode are two echocardiographic approaches which are equally effective in the investigation of foetal atrial extrasystoles and probably of sustained foetal bradycardia. However, Doppler recording of SVC/Ao gives a more detailed and precise diagnosis of more complex foetal arrhythmias.

Human herpesvirus 8 viral FLICE-inhibitory protein inhibits Fas-mediated apoptosis through binding and prevention of procaspase-8 maturation

Viral FLICE-inhibitory proteins (v-FLIPs) encoded by several herpesviruses and poxviruses share the ability to inhibit apoptosis after engagement of death receptors. In the current article, we provide insights into the mechanisms by which the v-FLIP of human herpesvirus 8 (HHV-8) (also referred to as Kaposi's sarcoma-associated virus) protects cells from apoptosis after Fas-induced signaling. Using v-FLIP expression vectors, our results clearly show that HHV-8 v-FLIP reduces the cleavage of procaspase-8 into its active p18 and p10 protease subunits upon Fas-induced cell death. These results were confirmed by lower caspase-8 and caspase-3 protease activities in extracts of HeLa cells expressing HHV-8 v-FLIP. Coimmunoprecipitation studies further indicate that HHV-8 v-FLIP physically interacts with procaspase-8, but not with Fas-associated protein with death domain in the cellular cytoplasm. These results suggest that binding of HHV-8 v-FLIP to procaspase-8 affects the recruitment and the activation of the latter at the death-induced signaling complex, resulting in diminished apoptotic cascade initiation. Because cellular FLIP was recently reported to modulate promoter containing NF-kappaB motifs and that both HHV-8 and human immunodeficiency virus type 1 (HWV-1) can infect monocytes, we studied the effects of v-FLIP on HIV-1 gene expression. Cotransfection experiments indicated that v-FLIP expression is associated with activation of HIV long terminal repeats: events that were strictly dependent on the presence of NF-kappaB consensus elements. In conclusion, HHV-8 v-FLIP can possibly contribute to the pathogenesis of both HHV-8 and HIV-1 through impaired Fas-dependent killing of infected cells by cytotoxic T cells and through activation of HIV gene expression.

Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years

OBJECTIVE

Experimental studies on fetal lambs have shown that during an increase in the resistance to placental flow the delivery of oxygen to the brain is preserved as long as net flow through the aortic isthmus is antegrade. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome.

STUDY DESIGN

Forty-four fetuses were retrospectively included in this study on the basis of an abnormal Doppler velocity in the umbilical artery. Mean gestational age at delivery was 33.0 +/- 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5).

RESULTS

Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth.

CONCLUSION

Measuring the ratio of antegrade to retrograde velocity integrals in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.

Doppler and M-mode ultrasonography to time fetal atrial and ventricular contractions

OBJECTIVE

To compare ease of recording and reliability of ultrasonographic approaches used to time fetal heart atrial and ventricular contractions.

METHODS

Seventeen consecutive fetuses seen at our fetal cardiology unit for possible fetal cardiac arrhythmia were included in this study. The same ultrasonographer obtained M-mode tracings of atrial and ventricular free walls, atrial wall and opening of the aortic valves, a peak of the mitral valve, and the opening of the aortic valves; and Doppler signals of flow-velocity waveforms in the outflow tract of the left ventricle and simultaneous flow-velocity waveforms in the aorta and superior vena cava. The outcome measures were rate of successful attempts and intra- and interobserver reliability coefficients.

RESULTS

Valid recordings were made for all patients with one M-mode (atrial and ventricular free walls) and two Doppler (intraventricular, superior vena cava, and ascending aorta) approaches. Atrioventricular intervals were significantly longer with M-mode compared with Doppler ultrasonography. Reliability coefficients were excellent (at least 0.89) for all intraobserver measurements. Comparisons of atrioventricular and ventriculoatrial interval measurements made by two observers gave the following intraclass correlation coefficients (95% confidence interval): atrioventricular = M-mode: 0.87 (0.79, 0. 91), left ventricular outflow: 0.93 (0.89, 0.96), superior vena cava-aorta: 0.98 (0.97, 0.99); ventriculoatrial = M-mode: 0.79 (0.67, 0.87), left ventricular outflow: 0.97 (0.95, 0.98); superior vena cava-aorta: 0.99 (0.98, 0.99).

CONCLUSION

Fetal atrioventricular intervals measured indirectly from M-mode or Doppler tracings were equally reliable when measured by the same observer; the Doppler approaches had better correlation between measurements made by two different observers.

EBV suppresses prostaglandin E2 biosynthesis in human monocytes

It is well known that EBV has developed strategies to evade immune surveillance. Previously, EBV was shown to bind specifically to monocytes and regulate expression of proinflammatory mediators such as IL-1, IL-6, TNF-alpha, and leukotrienes. EBV was also found to affect phagocytosis of monocytes. In this study, we show that in addition to these effects, EBV suppresses the biosynthesis of PGE2, a pleiotropic immunomodulatory molecule that is synthesized by the dioxygenation of arachidonic acid via the cyclooxygenase (COX) pathway. This down-regulation of PGE2 formation involved the inhibition of the inducible COX-2 isoform expression both at the transcriptional and translational levels, whereas expression of the constitutive COX-1 isoform was unaltered. Furthermore, exposure of monocytes to EBV was found to impact on the NF-kappaB activation pathway, which plays an essential role in the induction of COX-2 in monocytes. The inhibition of PGE2 biosynthesis was relieved when the experiments were conducted in presence of phosphonoacetic acid, an inhibitor of herpesviruses DNA polymerase, indicating that viral replication and/or neosynthesized viral proteins were involved in this process. Thus, inhibition of PGE2 biosynthesis in monocytes may represent an additional mechanism underlying EBV pathogenicity.

[Comparison of behavior characteristics of the spontaneously alert state and the liberated state in the term newborn]

Occupational therapists evaluate the capacities of infants at younger ages than ever before. The variability of the infants' state has an inevitable influence on the expression of their behaviours. In order to counter the effect of this instability, Grenier (1985) suggests inducing the "liberated state," which optimizes the infant's level of attention. The aim of this study was to identify the behaviours that discriminate this liberated state from the alert state (state 4) as described by Brazelton (1973). Some of the parameters that were defined in the Synactive Theory of Development Model (Als, 1982) were used in order to document the behaviours of the infants observed in the two different states. The average age of the infants, at the time of observation, was 62 hours. The duration of the observation was 5 minutes. Among the 54 newborns that were evaluated, 21 were observed in the two states under study; 33 were evaluated in one state only. The results confirm a greater stability of the "liberated state". Stress and self-regulation behaviours, and the need for external regulation are less frequent in this state; these differences are statistically significant (p < 0.05). Goal-directed movements are more frequent in the "liberated state" (p < 0.001). The authors suggest the use of the "liberated state" to further document the early capacities of infants.

Infection of primary human monocytes by Epstein-Barr virus

Previous studies have reported that infection of monocytes by viruses such as cytomegalovirus and human immunodeficiency virus weakens host natural immunity. In the present study, we demonstrated the capability of Epstein-Barr virus (EBV) to infect and replicate in freshly isolated human monocytes. Using electron microscopy analysis, we observed the presence of EBV virions in the cytoplasm and nuclei of approximately 20% of monocytes. This was confirmed by Southern blot analysis of EBV genomic DNA sequences in isolated nuclei from monocytes. Infection of monocytes by EBV leads to the activation of the replicative cycle. This was supported by the detection of immediate-early lytic mRNA BZLF-1 transcripts, and by the presence of two early lytic transcripts (BALF-2, which appears to function in DNA replication, and BHRF-1, also associated with the replicative cycle). The late lytic BcLF-1 transcripts, which code for the major nucleocapsid protein, were also detected, as well as EBNA-1 transcripts. However, attempts to detect EBNA-2 transcripts have yielded negative results. Viral replication was also confirmed by the release of newly synthesized infectious viral particles in supernatants of EBV-infected monocytes. EBV-infected monocytes were found to have significantly reduced phagocytic activity, as evaluated by the quantification of ingested carboxylated fluoresceinated latex beads. Taken together, our results suggest that EBV infection of monocytes and alteration of their biological functions might represent a new mechanism to disrupt the immune response and promote viral propagation during the early stages of infection.

Interleukin-15 as an activator of natural killer cell-mediated antiviral response

Natural killer (NK) cells are large granular lymphocytes capable of efficient killing of virus-infected and tumor cells in a major histocompatibility complex-independent manner. The cytotoxic killing potential of NK cells can be modulated by a variety of factors, including cytokines such as interleukin-12 (IL-12), IL-15, and interferon (IFN). IL-15 also plays an important role in NK cell development and survival. Killing of virally infected cells by NK cells is likely to represent an important antiviral defense mechanism, especially during the early phase of infection when antigen-specific immunity has yet to be generated. In the present work, we studied the potential of IL-15 to act as a modulator of NK cell-mediated antiviral defense. Our results clearly indicate that IL-15 can curtail infections by 3 human herpesviruses: Herpes simplex virus type 1, Epstein-Barr virus, and human herpesvirus 6. The antiviral activity of IL-15 is dose-, time-, and NK cell-dependent. IL-15-treated NK cells showed an increased killing potential against a variety of cells, including virus-infected target cells. Lastly, using highly purified cell population, we report that IL-15 triggers the synthesis of IFN-gamma from both CD4(+) and NK cells, which can act in both autocrine and paracrine fashion to modulate NK cells cytotoxic potential. In conclusion, IL-15 is a cytokine that can contribute to the establishment of an antiviral state in 2 ways: first by increasing the killing ability of NK cells and second by stimulating the synthesis and secretion of IFN.