Spectrum of chest computed tomographic (CT) findings in coronavirus disease-19 (COVID-19) patients in India.

PURPOSE: To report the spectrum of chest computed tomographic (CT) imaging findings in coronavirus disease-19 (COVID-19) infected Indian patients. METHODS: This was a prospective descriptive study comprising 147 consecutive reverse transcriptase polymerase chain reaction (RT-PCR) positive patients who underwent CT chest. Prevalence, distribution, extent and type of abnormal lung findings were recorded. RESULTS: Among the total study cohort of 147 patients, 104 (70.7 %) were males and 43 (29.3 %) were females with mean age of 40.9 ±â€¯17.2 years (range 24-71 years). We observed lung parenchymal abnormalities in 51 (34.7 %) cases whereas 96 (65.3 %) RT-PCR positive cases had a normal chest CT. Only 12.2 % of the patients were dyspneic, 6.1 % had desaturation, 7.4 % had increased respiratory rate and 10.9 % had comorbidities. Among the patients with abnormal CT findings bilateral 39/51 (76.5 %), multilobar (88.2 %) lung involvement with a predominant peripheral and posterior distribution was commonly observed. With regards to the type of opacity, ground glass opacity (GGO) was the dominant abnormality found in all 51 (100 %) cases. Pure GGO was observed in 15 (29.4 %), GGO with crazy paving pattern was seen in 15 (29.4 %) and GGO mixed with consolidation was noted in 21(41.2 %). Peri-lesional or intralesional segmental or subsegmental pulmonary vessel enlargement was observed in 36 (70.6 %) cases. CONCLUSION: In this study population predominantly with mild symptoms and few comorbidities, two-thirds of RT-PCR positive patients had a normal chest CT; whereas the remaining patients showed typical findings of predominant GGOs with a bilateral distribution and peripheral predominance.

Heart Dysfunction Following Long-Term Murine Cytomegalovirus Infection: Fibrosis, Hypertrophy, and Tachycardia.

Human cytomegalovirus (HCMV) is associated with increased risk of chronic diseases of the heart and vasculature, including myocarditis, atherosclerosis, and transplant vasculopathy. To investigate CMV infection of the heart, murine cytomegalovirus (MCMV) was used to evaluate both acute and latent infection and the subsequent phenotypic and functional consequences of infection. Female BALB/c mice were intraperitoneally (i.p.) inoculated with 1 × 106 pfu of MCMV and evaluated at 14 and 50 days postinfection (dpi). At each time point, echocardiography was used to evaluate cardiac function and histology was conducted for phenotypic evaluation. MCMV replication in the heart was detected as early as 3 dpi and was no longer detectable at 14 dpi. Infected animals had significant cardiac pathology at 14 and 50 dpi when compared to uninfected controls. Histology revealed fibrosis of the heart as early as 14 dpi and the presence of white fibrous deposits on the surface of the heart. Functional evaluation showed significantly increased heart rate and muscle thickening in the latently infected animals when compared to the control animals. At 50 dpi, latent virus was measured by explant reactivation assay, demonstrating that MCMV establishes latency and is capable of reactivation from the heart, similar to other tissues such as spleen and salivary glands. Collectively, these studies illustrate that MCMV infection results in phenotypic alterations within the heart as early as 14 dpi, which progress to functional abnormalities during latency. These findings are similar to sinus tachycardia and hypertrophy of the heart muscle observed in cases of HCMV-induced acute myocarditis.

Frequent detection of Saffold cardiovirus in adenoids.

Saffold virus (SAFV) is classified into the Cardiovirus genus of the Picornaviridae family. Up to now, eleven genotypes have been identified however, their clinical significance remains unclear. Here, we investigated the presence of SAFV in asymptomatic patients admitted for adenoidectomy. A total of 70 adenoid tissue samples were collected from children with clinical symptoms caused by hypertrophy of adenoids but without symptoms of airway infection. Samples were investigated for SAFV by RT-nested PCR and sequence analysis. Eleven of 70 (15.7%) samples were positive for SAFV. Nasopharyngeal swabs were available from 45 children just before surgery. SAFV was rarely found and only in children with SAFV-positive adenoids 2/8. Our findings indicate that the presence of SAFV seems to be more frequent in adenoid tissue than expected. This could support the notion of a longer than previously anticipated persistence of SAFV nucleic acids in the respiratory tract and possibly a chronic infection. Further investigations are necessary to establish the role of SAFV infection in humans.

Multiplex detection in tonsillar tissue of all known human polyomaviruses.

BACKGROUND: In the past few years, eleven new human viruses have joined the two previously known members JCPyV and BKPyV of the Polyomaviridae family, by virtue of molecular methods. Serology data suggest that infections with human polyomaviruses (HPyVs) occur since childhood and the viruses are widespread in the general population. However, the viral persistence sites and transmission routes are by and large unknown. Our previous studies demonstrated that the four new HPyVs - KIPyV, WUPyV, MCPyV and TSPyV - were present in the tonsils, and suggested lymphoid tissue as a persistent site of these emerging human viruses. We developed a Luminex-based multiplex assay for simultaneous detection of all 13 HPyVs known, and explored their occurrence in tonsillar tissues of children and adults mostly with tonsillitis or tonsillar hypertrophy. METHODS: We set up and validated a new Luminex-based multiplex assay by using primer pairs and probes targeting the respective HPyV viral protein 1 (VP1) genes. With this assay we tested 78 tonsillar tissues for DNAs of 13 HPyVs. RESULTS: The multiplex assay allowed for simultaneous detection of 13 HPyVs with high analytical sensitivity and specificity, with detection limits of 100-102 copies per microliter, and identified correctly all 13 target sequences with no cross reactions. HPyV DNA altogether was found in 14 (17.9%) of 78 tonsils. The most prevalent HPyVs were HPyV6 (7.7%), TSPyV (3.8%) and WUPyV (3.8%). Mixed infection of two HPyVs occurred in one sample. CONCLUSIONS: The Luminex-based HPyV multiplex assay appears highly suitable for clinical diagnostic purposes and large-scale epidemiological studies. Additional evidence was acquired that the lymphoid system plays a role in HPyV infection and persistence. Thereby, shedding from this site during reactivation might take part in transmission of the newly found HPyVs.

A Pilot Study on the Treatment of Posterior Cheek Enlargement in HIV+ Patients With Botulinum Toxin A.

BACKGROUND: Posterior cheek enlargement in human immunodeficiency virus (HIV)+ individuals can lead to significant cosmetic disfigurement. Both parotid gland and masseter muscle overlie the mandibular ramus, contributing to lower facial contour. However, posterior cheek enlargement has not been well characterized anatomically. There are also limited treatment options. Botulinum toxin is a highly efficacious minimally invasive option for improving the shape of the lower face. OBJECTIVE: A pilot study was undertaken to better characterize posterior cheek enlargement in HIV+ patients and explore treatment with botulinum toxin A. MATERIALS AND METHODS: Five HIV+ patients with posterior cheek enlargement were treated with botulinum toxin A. Clinical, photographic, and radiological evaluations allowed the precise calculation of any change in volumes resulting from botulinum toxin A. RESULTS: All 5 patients had a good response with a mean decrease of 21.4% and 11.2% in the volumes of the masseter muscle and parotid gland, respectively. The effect was long lasting even at 6 months after injection and well tolerated. CONCLUSION: Botulinum toxin A may be a less invasive treatment of posterior cheek enlargement in HIV+ patients, with advantages of a good result that is long lasting with good tolerability and minimal risk.

Ultrasound and histopathological features of myocardial involvement in HIV infection in children.

AIM: HIV infection in children is an important clinical and pathologic entity, which embraces many forms of presentation and can involve multiple organs and systems. This study aimed at identifying the main forms of cardiovascular involvement in HIV-infected children with horizontally transmitted disease and describing them with the aid of ultrasound and histopathological examinations. RESULTS: We recorded cardiovascular anomalies in 79 (67.52%) patients out of the 117 comprised in the study population, and noted the following prevalence distribution: systolic dysfunction in 49 (41.88%) patients, left ventricular hypertrophy (LVH) in 30 (25.6%) patients, right ventricular hypertrophy (RVH) in 15 (12.82%) patients, and dilated cardiomyopathy (DCM) in 22 (18.8%) patients. We also carried out post-mortem histopathological examinations in five patients, and observed the main modification incurred by the disease. CONCLUSIONS: Cardiac involvement during HIV infection differs significantly in different mechanisms of virus transmission, and the horizontal transmission of HIV yields a lower prevalence of this type of pathology. The general diagnostic picture can be significantly improved by adding histopathological examination to the ultrasonographic method of investigation.

Hypertrophic adenoid is a major infection site of human bocavirus 1.

Human bocavirus 1 (HBoV1) is associated with respiratory infections worldwide, mainly in children. Similar to other parvoviruses, it is believed that HBoV1 can persist for long periods of time in humans, probably through maintaining concatemers of the virus single-stranded DNA genome in the nuclei of infected cells. Recently, HBoV-1 was detected in high rates in adenoid and palatine tonsils samples from patients with chronic adenotonsillar diseases, but nothing is known about the virus replication levels in those tissues. A 3-year prospective hospital-based study was conducted to detect and quantify HBoV1 DNA and mRNAs in samples of the adenoids (AD), palatine tonsils (PT), nasopharyngeal secretions (NPS), and peripheral blood (PB) from patients undergoing tonsillectomy for tonsillar hypertrophy or recurrent tonsillitis. HBoV1 was detected in 25.3% of the AD samples, while the rates of detection in the PT, NPS, and PB samples were 7.2%, 10.5%, and 1.7%, respectively. The viral loads were higher in AD samples, and 27.3% of the patients with HBoV had mRNA detectable in this tissue. High viral loads and detectable mRNA in the AD were associated with HBoV1 detection in the other sample sites. The adenoids are an important site of HBoV1 replication and persistence in children with tonsillar hypertrophy. The adenoids contain high HBoV1 loads and are frequently positive for HBoV mRNA, and this is associated with the detection of HBoV1 in secretions.

Underlying liver disease influences volumetric changes in the spared hemiliver after selective internal radiation therapy with 90Y in patients with hepatocellular carcinoma.

OBJECTIVE: Hypertrophy of the contralateral liver lobe after treatment with yttrium-90 ((90)Y) microspheres has recently been reported. This study aimed to quantify left hepatic lobe hypertrophy after right-sided radioembolization for hepatocellular carcinoma (HCC) and to identify pretreatment predictive factors of hypertrophy in an Asian population. METHODS: A retrospective review of patients with inoperable HCC undergoing selective internal radiation treatment (SIRT) with (90)Y microspheres at a single institution from January 2008 to January 2012 was performed. Only patients who had treatment delivered via the right hepatic artery alone were included. RESULTS: In all, 17 patients fulfilling the study criteria were identified. The mean percentage of left-lobe hypertrophy was 34.2% ± 34.9% (range 19.0-106.5%) during a median of 5-month follow-up. Patients with hepatitis B were found to experience a significantly greater degree of hypertrophy than those with hepatitis C or alcoholic liver cirrhosis. There were no cases of acute liver failure after the administration of SIRT in this study and none of the patients developed disease in the contralateral lobe over the study period. CONCLUSIONS: Administration of unilobar SIRT to the right liver lobe in patients with HCC resulted in a significant degree of contralateral left lobe hypertrophy. Patients with hepatitis B experienced a greater degree of hypertrophy than those with hepatitis C or alcoholic liver cirrhosis.

Prevalence of human papillomavirus and Epstein-Barr virus DNA in Chinese children with tonsillar and/or adenoidal hypertrophy.

Tonsillar and adenoidal hypertrophy are prevalent otolaryngologic disorders in children, but their pathogenesis is largely unknown. The presence of human papillomavirus (HPV) and Epstein-Barr virus (EBV) DNA in 146 tonsil and/or adenoid tissue specimens from 104 Chinese children with tonsillar and/or adenoidal hypertrophy were screened using flow-through hybridization gene-chip technology and real-time fluorescence-based quantitative PCR. Then, the relationships between the prevalence of the viruses and other clinical characteristics of tonsillar and/or adenoidal hypertrophy were analyzed. No patient had HPV DNA. EBV DNA was detected in 19/42 (45.2%) tonsil tissues and 72/104 (69.2%) adenoid tissue specimens (P < 0.05). EBV DNA was not related to the patients' age, gender, disease course, or nationality, but children positive for EBV were less likely to snore; 14/15 (93.3%) patients who did not snore and 59/89 (66.3%) patients who snored were EBV positive. EBV DNA, but not HPV DNA was detected in Chinese children with tonsillar and/or adenoidal hypertrophy. Adenoid tissues might more susceptible than tonsil tissues to EBV infection. In addition, EBV infection did not aggravate snoring in patients with tonsillar and/or adenoidal hypertrophy.

Microbiological profile of adenoid hypertrophy correlates to clinical diagnosis in children.

OBJECTIVE: Adenoid hypertrophy is a common condition in childhood, which may be associated with recurring acute otitis media (RAOM), otitis media with effusion (OME), and obstructive sleep apnea syndrome (OSAS). These different clinical characteristics have some clinical overlap; however, they might be explained by distinct immunologic and infectious profiles and result in various histopathologic findings of adenoid specimens. METHODS: A total of 59 children with adenoid hypertrophy undergoing adenoidectomy were studied. Three series of identical adenoid specimens were processed to hematoxylin-eosin (H.E.) and Gram staining and to respiratory virus specific real-time PCR, respectively. RESULTS: According to the clinical characteristics, patients were recruited into three groups: RAOM (n = 25), OME (n = 19), and OSAS (n = 15). Bacterial biofilms were detected in 21 cases, while at least one of the studied respiratory viruses was detected in 52 specimens. RAOM cases were significantly associated with biofilm existence (n = 20, P < 0.001). In contrast, OME group was characterized by the absence of bacterial biofilm and by normal mucosa. Showing a statistically significant correlation, all OME cases were positive for human bocavirus (HBoV, P < 0.001). CONCLUSIONS: Bacterial biofilms might contribute to the damage of respiratory epithelium and recurring acute infections resulting in RAOM. In OME cases persisting respiratory viruses, mainly HBoV, can cause subsequent lymphoid hyperplasia leading to ventilation disorders and impaired immunoreactivity of the middle ear cleft.

Managing hytrosavirus infections in Glossina pallidipes colonies: feeding regime affects the prevalence of salivary gland hypertrophy syndrome.

Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH) syndrome and the virus isolated from Glossina pallidipes (GpSGHV) has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. Due to the deleterious impact of SGHV on G. pallidipes colonies, several approaches were investigated to develop a virus management strategy. Horizontal virus transmission is the major cause of the high prevalence of the GpSGHV in tsetse colonies. Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections. However, due to the absence of disposable feeding equipment (feeding trays and silicone membranes), the implementation of a clean feeding approach remains economically difficult. We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources. The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9) virus copies in regular colonies to an average of 10(2.5) and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach. The clean feeding approach also reduced the virus load from an average of 10(8) virus copy numbers to an average of 10(3) virus copies and SGH prevalence of 10% to 4% in flies fed after the clean fed colony. Taken together, these data indicate that the clean feeding approach is applicable in large-scale G. pallidipes production facilities and eliminates the deleterious effects of the virus and the SGH syndrome in these colonies.

In vitro modeling of human bocavirus 1 infection of polarized primary human airway epithelia.

Human bocavirus 1 (HBoV1) is an emerging human-pathogenic respiratory virus. We characterized two important features of HBoV1 infection in polarized primary human airway epithelia (HAE). Apical HBoV1 infection of HAE at a low multiplicity of infection causes disruption of the tight junction barrier, loss of cilia, and epithelial cell hypertrophy, which are hallmarks of the airway epithelial damage caused by HBoV1 infection. HBoV1 also infects HAE from the basolateral surface productively, although less efficiently, and this also leads to the characteristic airway epithelial damage.

Correlation between structure, protein composition, morphogenesis and cytopathology of Glossina pallidipes salivary gland hypertrophy virus.

The Glossina pallidipes salivary gland hypertrophy virus (GpSGHV) is a dsDNA virus with rod-shaped, enveloped virions. Its 190 kb genome contains 160 putative protein-coding ORFs. Here, the structural components, protein composition and associated aspects of GpSGHV morphogenesis and cytopathology were investigated. Four morphologically distinct structures: the nucleocapsid, tegument, envelope and helical surface projections, were observed in purified GpSGHV virions by electron microscopy. Nucleocapsids were present in virogenic stroma within the nuclei of infected salivary gland cells, whereas enveloped virions were located in the cytoplasm. The cytoplasm of infected cells appeared disordered and the plasma membranes disintegrated. Treatment of virions with 1 % NP-40 efficiently partitioned the virions into envelope and nucleocapsid fractions. The fractions were separated by SDS-PAGE followed by in-gel trypsin digestion and analysis of the tryptic peptides by liquid chromatography coupled to electrospray and tandem mass spectrometry. Using the MaxQuant program with Andromeda as a database search engine, a total of 45 viral proteins were identified. Of these, ten and 15 were associated with the envelope and the nucleocapsid fractions, respectively, whilst 20 were detected in both fractions, most likely representing tegument proteins. In addition, 51 host-derived proteins were identified in the proteome of the virus particle, 13 of which were verified to be incorporated into the mature virion using a proteinase K protection assay. This study provides important information about GpSGHV biology and suggests options for the development of future anti-GpSGHV strategies by interfering with virus-host interactions.

Presence of herpesviruses in adenoid tissues of children with adenoid hypertrophy and chronic adenoiditis.

OBJECTIVES: The aim of study was to determine the presence of some of the herpesviruses including herpes simplex virus (HSV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV) in adenoid tissues of children with adenoid hypertrophy (AH) and chronic adenoiditis (CA) and to investigate the potential role of the herpesviruses in patogenesis of AH and CA. PATIENTS AND METHODS: A total of 72 patients (41 boys, 31 girls; mean age 4 years and 2 months; range 2 to 9 years) who underwent adenoidectomy or adenotonsillectomy (with or without placement of a ventilation tube) in our clinic between October 2007 and May 2008, were included. The patients were divided into two groups, as AH group (n=42) and the CA group (n=30). Adenoid tissues collected from patients in both groups were analyzed by polymerase chain reaction (PCR) for the presence of HSV, EBV and CMV-DNA. RESULTS: The results of the PCR indicated that 33.3% in the AH group and 36.6% in the CA group were herpesvirus DNA positive. Among the herpesviruses studied, HSV-DNA was detected at the highest level (14.2% and 16.6%, respectively) in both groups, although the difference between the groups was not significant. EBV-DNA positiveness was 11.9% and CMV-DNA was 4.7% in the AH group, whereas, EBV-DNA positiveness was 13.3% and CMV-DNA was 6.6% in the CA group. CONCLUSION: Herpesviruses were determined at a high rate in adenoid tissue of children with AH and CA, suggesting that there may be a potential relationship between the presence of herpesviruses and occurrence of AH and CA in children. However, more extensive studies are required to elucidate the role of herpesviruses in the pathogenesis of AH or CA.

Sudden death and Angelman syndrome.

Angelman syndrome is a condition characterized by developmental delay due to abnormalities in the maternally derived chromosome 15q11-q13. Typical features include impaired expressive language, an ataxic gait, and seizures. Hyperactivity may result in accidental bruises and abrasions, raising issues of possible inflicted injury. A fascination with water may predispose to drowning. A 5-year-old boy with an established diagnosis of Angelman syndrome is reported who died of upper airway obstruction due to massively enlarged tonsils complicating infectious mononucleosis. Assessment of the severity of underlying illness in developmentally delayed children may be difficult due to failure to vocalize worsening symptoms and distress. In addition, signs of upper airway narrowing due to infection in Angelman syndrome may be masked by the sucking and swallowing difficulties that affected individuals may have with drooling and excessive chewing and mouthing behavior.

Salivary gland hypertrophy virus of house flies in Denmark: prevalence, host range, and comparison with a Florida isolate.

House flies (Musca domestica) infected with Musca domestica salivary gland hypertrophy virus (MdSGHV) were found in fly populations collected from 12 out of 18 Danish livestock farms that were surveyed in 2007 and 2008. Infection rates ranged from 0.5% to 5% and averaged 1.2%. None of the stable flies (Stomoxys calcitrans), rat-tail maggot flies (Eristalis tenax) or yellow dung flies (Scathophaga stercoraria) collected from MdSGHV-positive farms displayed characteristic salivary gland hypertrophy (SGH). In laboratory transmission tests, SGH symptoms were not observed in stable flies, flesh flies (Sarcophaga bullata), black dump flies (Hydrotaea aenescens), or face flies (Musca autumnalis) that were injected with MdSGHV from Danish house flies. However, in two species (stable fly and black dump fly), virus injection resulted in suppression of ovarian development similar to that observed in infected house flies, and injection of house flies with homogenates prepared from the salivary glands or ovaries of these species resulted in MdSGHV infection of the challenged house flies. Mortality of virus-injected stable flies was the highest among the five species tested. Virulence of Danish and Florida isolates of MdSGHV was similar with three virus delivery protocols, as a liquid food bait (in sucrose, milk, or blood), sprayed onto the flies in a Potter spray tower, or by immersiion in a crude homogenate of infected house flies. The most effective delivery system was immersion in a homogenate of ten infected flies/ml of water, resulting in 56.2% and 49.6% infection of the house flies challenged with the Danish and Florida strains, respectively.

Tsetse salivary gland hypertrophy virus: hope or hindrance for tsetse control?

MANY SPECIES OF TSETSE FLIES (DIPTERA: Glossinidae) are infected with a virus that causes salivary gland hypertrophy (SGH), and flies with SGH symptoms have a reduced fecundity and fertility. The prevalence of SGH in wild tsetse populations is usually very low (0.2%-5%), but higher prevalence rates (15.2%) have been observed occasionally. The successful eradication of a Glossina austeni population from Unguja Island (Zanzibar) using an area-wide integrated pest management approach with a sterile insect technique (SIT) component (1994-1997) encouraged several African countries, including Ethiopia, to incorporate the SIT in their national tsetse control programs. A large facility to produce tsetse flies for SIT application in Ethiopia was inaugurated in 2007. To support this project, a Glossina pallidipes colony originating from Ethiopia was successfully established in 1996, but later up to 85% of adult flies displayed symptoms of SGH. As a result, the colony declined and became extinct by 2002. The difficulties experienced with the rearing of G. pallidipes, epitomized by the collapse of the G. pallidipes colony originating from Ethiopia, prompted the urgent need to develop management strategies for the salivary gland hypertrophy virus (SGHV) for this species. As a first step to identify suitable management strategies, the virus isolated from G. pallidipes (GpSGHV) was recently sequenced and research was initiated on virus transmission and pathology. Different approaches to prevent virus replication and its horizontal transmission during blood feeding have been proposed. These include the use of antiviral drugs such as acyclovir and valacyclovir added to the blood for feeding or the use of antibodies against SGHV virion proteins. In addition, preliminary attempts to silence the expression of an essential viral protein using RNA interference will be discussed.

HHV-6 infection of tonsils and adenoids in children with hypertrophy and upper airway recurrent infections.

OBJECTIVE: Human herpes virus 6 (HHV-6), the agent of a self-limiting exanthematic disease in childhood, persists in a silent state in the secondary lymphoid organs and the reactivation is characterized by HHV-6-induced inflammatory cytokines. This study investigates the possible etiological role of HHV-6 in children affected by tonsil and adenoid hypertrophy. METHODS: 55 tonsils, 80 adenoids fresh tissues and 74 blood samples were collected from 80 children (mean age 4.8 years, 43.5% female) undergoing elective tonsillectomy and/or adenoidectomy for tissue hypertrophy. Moreover, patients with <5 years old documented upper airway recurrent infections not related to relapsing of acute tonsillitis. Specific IgG antibodies and virus detection (by PCR, variant A/B enzymatic genotyping and real-time PCR) were performed. RESULTS: In our series, HHV-6 seroprevalence was tested at 50%. HHV-6 variant B was the unique strain finding in 25% of adenoids, in 12.7% of tonsils and in 4% of peripheral blood mononuclear cells (PBMCs). HHV-6-B was prevalent in tonsils of children affected by upper airway infections (17.8% vs 7.4%) while the adenoids represented the more frequent reservoir (30.7% vs 19.5%) in patients with hypertrophy. HHV-6 viral load was low, ranging from 80 to 600 copies/10(6) cells suggesting a latent/persistent phase of infection. CONCLUSION: These results reinforce the role of the secondary lymphoid organs as an important reservoir for HHV-6B. Nevertheless, infection of lymphoid cells, sustained by a low level of replication, could be sufficient to increase the local injury through an autologous mechanism of inflammation.