Barbara Cameron

Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study.

Abstract Objective To delineate the risk factors, symptom patterns, and longitudinal course of prolonged illnesses after a variety of acute infections. Design Prospective cohort study following patients from the time of acute infection with Epstein-Barr virus (glandular fever), Coxiella burnetii (Q fever), or Ross River virus (epidemic polyarthritis). Setting The region surrounding the township of Dubbo in rural Australia, encompassing a 200 km geographical radius and 104 400 residents. Participants 253 patients enrolled and followed at regular intervals over 12 months by self report, structured interview, and clinical assessment. Outcome measures Detailed medical, psychiatric, and laboratory evaluations at six months to apply diagnostic criteria for chronic fatigue syndrome. Premorbid and intercurrent illness characteristics recorded to define risk factors for chronic fatigue syndrome. Self reported illness phenotypes compared between infective groups. Results Prolonged illness characterised by disabling fatigue, musculoskeletal pain, neurocognitive difficulties, and mood disturbance was evident in 29 (12%) of 253 participants at six months, of whom 28 (11%) met the diagnostic criteria for chronic fatigue syndrome. This post-infective fatigue syndrome phenotype was stereotyped and occurred at a similar incidence after each infection. The syndrome was predicted largely by the severity of the acute illness rather than by demographic, psychological, or microbiological factors. Conclusions A relatively uniform post-infective fatigue syndrome persists in a significant minority of patients for six months or more after clinical infection with several different viral and non-viral micro-organisms. Post-infective fatigue syndrome is a valid illness model for investigating one pathophysiological pathway to chronic fatigue syndrome.

Sequential Bottlenecks Drive Viral Evolution in Early Acute Hepatitis C Virus Infection

Hepatitis C is a pandemic human RNA virus, which commonly causes chronic infection and liver disease. The characterization of viral populations that successfully initiate infection, and also those that drive progression to chronicity is instrumental for understanding pathogenesis and vaccine design. A comprehensive and longitudinal analysis of the viral population was conducted in four subjects followed from very early acute infection to resolution of disease outcome. By means of next generation sequencing (NGS) and standard cloning/Sanger sequencing, genetic diversity and viral variants were quantified over the course of the infection at frequencies as low as 0.1%. Phylogenetic analysis of reassembled viral variants revealed acute infection was dominated by two sequential bottleneck events, irrespective of subsequent chronicity or clearance. The first bottleneck was associated with transmission, with one to two viral variants successfully establishing infection. The second occurred approximately 100 days post-infection, and was characterized by a decline in viral diversity. In the two subjects who developed chronic infection, this second bottleneck was followed by the emergence of a new viral population, which evolved from the founder variants via a selective sweep with fixation in a small number of mutated sites. The diversity at sites with non-synonymous mutation was higher in predicted cytotoxic T cell epitopes, suggesting immune-driven evolution. These results provide the first detailed analysis of early within-host evolution of HCV, indicating strong selective forces limit viral evolution in the acute phase of infection.

Production of pro-inflammatory cytokines correlates with the symptoms of acute sickness behaviour in humans.

BACKGROUND Elaboration of the concept of cytokine-induced sickness behaviour in recent years has opened new avenues for understanding brain involvement in sickness and recovery processes. Additionally, this has led to much speculation about the role of the immune system in neuropsychiatric syndromes, including depression and chronic fatigue. However, few studies have examined this phenomenon as it naturally occurs in sick humans, and none has attempted to document the quantitative relationships between cytokine levels and non-specific symptoms. The aim of this research was to examine human sickness behaviour and its immunological correlates in documented Epstein-Barr virus (EBV), Q fever or Ross River virus (RRV) infections. METHOD We studied two separate samples. The first consisted of 21 patients with acute Q fever. The second included 48 patients with acute RRV or EBV infection. Psychological and somatic symptom profiles were derived from self-report measures completed at enrolment. Quantification of proinflammatory cytokines [interleukin (IL)-1beta and IL-6] in sera and supernatants of peripheral blood mononuclear cell (PBMC) cultures was undertaken by specific ELISAs. RESULTS Levels of IL-1beta and IL-6 spontaneously released from PBMC cultures were consistently correlated with reported manifestations of acute sickness behaviour including fever, malaise, pain, fatigue, mood and poor concentration. CONCLUSIONS IL-1beta and IL-6 produced as part of the host response represent sensitive markers of sickness behaviour in humans with acute infection. Further work is needed to systematically characterize the spectrum and natural history of sickness behaviour in humans and to elucidate its biological basis.

Plasma Apolipoprotein Levels Are Associated with Cognitive Status and Decline in a Community Cohort of Older Individuals

Objectives Apolipoproteins have recently been implicated in the etiology of Alzheimer’s disease (AD). In particular, Apolipoprotein J (ApoJ or clusterin) has been proposed as a biomarker of the disease at the pre-dementia stage. We examined a group of apolipoproteins, including ApoA1, ApoA2, ApoB, ApoC3, ApoE, ApoH and ApoJ, in the plasma of a longitudinal community based cohort. Methods 664 subjects (257 with Mild Cognitive Impairment [MCI] and 407 with normal cognition), mean age 78 years, from the Sydney Memory and Aging Study (MAS) were followed up over two years. Plasma apolipoprotein levels at baseline (Wave 1) were measured using a multiplex bead fluorescence immunoassay technique. Results At Wave 1, MCI subjects had lower levels of ApoA1, ApoA2 and ApoH, and higher levels of ApoE and ApoJ, and a higher ApoB/ApoA1 ratio. Carriers of the apolipoprotein E ε4 allele had significantly lower levels of plasma ApoE, ApoC3 and ApoH and a significantly higher level of ApoB. Global cognitive scores were correlated positively with ApoH and negatively with ApoJ levels. ApoJ and ApoE levels were correlated negatively with grey matter volume and positively with cerebrospinal fluid (CSF) volume on MRI. Lower ApoA1, ApoA2 and ApoH levels, and higher ApoB/ApoA1 ratio, increased the risk of cognitive decline over two years in cognitively normal individuals. ApoA1 was the most significant predictor of decline. These associations remained after statistically controlling for lipid profile. Higher ApoJ levels predicted white matter atrophy over two years. Conclusions Elderly individuals with MCI have abnormal apolipoprotein levels, which are related to cognitive function and volumetric MRI measures cross-sectionally and are predictive of cognitive impairment in cognitively normal subjects. ApoA1, ApoH and ApoJ are potential plasma biomarkers of cognitive decline in non-demented elderly individuals.

Cytokine Polymorphisms Have a Synergistic Effect on Severity of the Acute Sickness Response to Infection

BACKGROUND Functional polymorphisms in immune response genes are increasingly recognized as important contributors to the marked individual differences in susceptibility to and outcomes of infectious disease. The acute sickness response is a stereotypical set of illness manifestations mediated by the proinflammatory cytokines induced by many different pathogens. The genetic determinants of severity of the acute sickness response have not previously been explored. METHODS We examined the impact of functional polymorphisms in cytokine genes with critical roles in the early immune response (tumor necrosis factor-alpha, interleukin-6, interleukin-10, and interferon-gamma) on the severity and duration of illness following acute infection with Epstein-Barr virus, Coxiella burnetii (the causative agent of Q fever), or Ross River virus. RESULTS We found that the interferon-gamma +874T/A and the interleukin-10 -592C/A polymorphisms significantly affected illness severity, cytokine protein levels, and the duration of illness. These cytokine genotypes acted in synergy to potentiate their influence on disease outcomes. CONCLUSIONS These findings suggest that genetically determined variations in the intensity of the inflammatory response underpin the severity of the acute sickness response and predict the recovery time across varied infections.

Postinfective Fatigue Syndrome Is Not Associated with Altered Cytokine Production

Peripheral blood specimens and clinical data were obtained over a 12-month period from subjects in the Dubbo Infection Outcomes Study to examine cytokine production in postinfective fatigue syndrome. Ex vivo production of 8 cytokines was examined in 22 case patients and in 42 control subjects who recovered promptly. No significant differences were found. Ongoing production of the cytokines examined does not play a role in postinfective fatigue syndrome.

Preliminary evidence of mitochondrial dysfunction associated with post-infective fatigue after acute infection with Epstein Barr Virus

BackgroundAcute infectious diseases are typically accompanied by non-specific symptoms including fever, malaise, irritability and somnolence that usually resolve on recovery. However, in some individuals these symptoms persist in what is commonly termed post-infective fatigue. The objective of this pilot study was to determine the gene expression correlates of post-infective fatigue following acute Epstein Barr virus (EBV) infection.MethodsWe followed 5 people with acute mononucleosis who developed post-infective fatigue of more than 6 months duration and 5 HLA-matched control subjects who recovered within 3 months. Subjects had peripheral blood mononuclear cell (PBMC) samples collected at varying time points including at diagnosis, then every 2 weeks for 3 months, then every 3 months for a year. Total RNA was extracted from the PBMC samples and hybridized to microarrays spotted with 3,800 oligonucleotides.ResultsThose who developed post-infective fatigue had gene expression profiles indicative of an altered host response during acute mononucleosis compared to those who recovered uneventfully. Several genes including ISG20 (interferon stimulated gene), DNAJB2 (DnaJ [Hsp40] homolog and CD99), CDK8 (cyclin-dependent kinase 8), E2F2 (E2F transcription factor 2), CDK8 (cyclin-dependent kinase 8), and ACTN2 (actinin, alpha 2), known to be regulated during EBV infection, were differentially expressed in post-infective fatigue cases. Several of the differentially expressed genes affect mitochondrial functions including fatty acid metabolism and the cell cycle.ConclusionThese preliminary data provide insights into alterations in gene transcripts associated with the varied clinical outcomes from acute infectious mononucleosis.

Prolonged Illness after Infectious Mononucleosis Is Associated with Altered Immunity but Not with Increased Viral Load

BACKGROUND Primary Epstein-Barr virus (EBV) infection causes a spectrum of characteristics that range from asymptomatic seroconversion to severe infectious mononucleosis (IM), sometimes with prolonged symptoms and disability. We examined the relationships between clinical course, number of viral copies, and immunological parameters in a prospective cohort of subjects with recent IM. METHODS Eight case patients with at least 6 months of disabling symptoms and 31 matched control subjects who had recovered promptly were included. Symptom scores were recorded at regular intervals over the course of 12 months. Cellular EBV load, EBV-specific antibody responses, lymphocyte subsets, and EBV-specific interferon (IFN)- gamma induction were measured. RESULTS In case patients with prolonged illness, the severity of acute-phase symptoms was greater, the development of anti-EBV nuclear antigen-1 immunoglobulin G was more rapid, and the time to development of the peak IFN- gamma response to the majority of latent-cycle EBV peptides was generally slower than those in control subjects. However, in both groups, neither viral nor immune parameters correlated with the severity or duration of symptoms. CONCLUSIONS The resolution of symptomatic IM is not determined by control of viremia, nor is it easily explained by altered host responses to EBV infection. The detailed determinants of delayed recovery remain to be elucidated.

HIV and co-infections

Despite significant reductions in morbidity and mortality secondary to availability of effective combination anti‐retroviral therapy (cART), human immunodeficiency virus (HIV) infection still accounts for 1.5 million deaths annually. The majority of deaths occur in sub‐Saharan Africa where rates of opportunistic co‐infections are disproportionately high. In this review, we discuss the immunopathogenesis of five common infections that cause significant morbidity in HIV‐infected patients globally. These include co‐infection with Mycobacterium tuberculosis, Cryptococcus neoformans, hepatitis B virus, hepatitis C virus, and Plasmodium falciparum. Specifically, we review the natural history of each co‐infection in the setting of HIV, the specific immune defects induced by HIV, the effects of cART on the immune response to the co‐infection, the pathogenesis of immune restoration disease (IRD) associated with each infection, and advances in the areas of prevention of each co‐infection via vaccination. Finally, we discuss the opportunities and gaps in knowledge for future research.

Serological and virological investigation of the role of the herpesviruses EBV, CMV and HHV-6 in post-infective fatigue syndrome.

Multiple previous studies have sought evidence for ongoing, active infection with, or reactivation of, Herpesviruses in patients with chronic fatigue syndrome (CFS), with conflicting results. This study aimed to clarify this by studying 20 patients enrolled in a well‐characterized model of the onset and evolution of CFS, the prospective cohort of the Dubbo Infection Outcomes Study (DIOS). The patients selected for examination included five CFS patients with primary Epstein–Barr virus (EBV) infection; five CFS patients with acute viral infection not caused by EBV; and 10 matched controls with prompt resolution of primary EBV infection. Serum samples from three timepoints were assayed using a comprehensive range of serological assays for EBV, HHV‐6, and CMV. Viral genomes were assessed using quantitative PCR assays. All patients were seropositive for HHV‐6, and 10 were seropositive for CMV at infection baseline (five patients and five controls). Low titer CMV IgM antibodies were found at infection baseline in two of these cases and three control patients. HHV‐6 IgG antibody titers were highest at infection baseline but did not differ between the CFS cases and the control patients. There were increases in EBV IgG VCA p18, EBNA‐1 IgG, and EA IgG titers over time, but these did not differ between CFS cases and control patients. EBV and HHV6 DNA levels were at control levels in a minority of samples, and CMV was undetectable in all samples. These data do not support the hypothesis of ongoing or reactivated EBV, HHV‐6, or CMV infection in the pathogenesis of CFS. J. Med. Virol. 82:1684–1688, 2010. 2010 Wiley‐Liss, Inc.