NIH conference. Chronic fatigue syndrome research. Definition and medical outcome assessment.

A workshop was held 18 to 19 March 1991 at the National Institutes of Health to address critical issues in research concerning the chronic fatigue syndrome (CFS). Case definition, confounding diagnoses, and medical outcome assessment by laboratory and other means were considered from the perspectives of key medical specialties involved in CFS research. It was recommended that published Centers for Disease Control (CDC) case-definition criteria be modified to exclude fewer patients from analysis because of a history of psychiatric disorder. Specific recommendations were made concerning the inclusion or exclusion of other major confounding diagnoses, and a standard panel of laboratory tests was specified for initial patient evaluation. The workshop emphasized the importance of recognizing other conditions that could explain the patient's symptoms and that may be treatable. It was viewed as essential for the investigator to screen for psychiatric disorder using a combination of self-report instruments followed by at least one structured interview to identify patients who should be excluded from studies or considered as a separate subgroup in data analysis. Because CFS is not a homogeneous abnormality and because there is no single pathogenic mechanism, research progress may depend upon delineation of these and other patient subgroups for separate data analysis. Despite preliminary data, no physical finding or laboratory test was deemed confirmatory of the diagnosis of CFS. For assessment of clinical status, investigators must rely on the use of standardized instruments for patient self-reporting of fatigue, mood disturbance, functional status, sleep disorder, global well-being, and pain. Further research is needed to develop better instruments for quantifying these domains in patients with CFS.

Persistence of vaccine-induced immune responses to rubella: comparison with natural infection.

Serologic responses and patterns of antibody persistence in children given HPV-77 DE-5 or RA27/3 vaccine were compared with those in children who had experienced natural infection. The results indicated that both vaccines induce long-lasting immunity in most individuals. RA27/3 vaccine proved more immunogenic and resulted in higher antibody titers; after 11 years 95% of those who seroconverted who were tested had hemagglutination-inhibiting (HAI) antibodies and 100% had neutralizing (NT) antibodies. Titers in HPV-77 DE-5 vaccinees were lower, and in 16% of those whose immune responses were feeble, HAI titers decreased to less than 1:8 after nine to 12 years; however, when their sera were examined by the more sensitive latex-agglutination test, all but two were found to have specific rubella antibody at levels of 1:1 to 1:16. Natural infection with wild virus was shown to induce more vigorous immune responses than did either vaccine: antibody titers were higher, decreases were smaller, and none fell to less than 1:8 (HAI) or less than 1:4 (NT).

Immunoglobulin profiles provide new insights into infectious diseases.

New technologies are being developed which will facilitate measurement of IgG subclass responses to disease and vaccination. To illustrate the potential benefit of determining antibody subclass profiles, special features of the less abundant subclasses are discussed in relation to specific infectious disease problems.

Neutralizing and hemagglutination-inhibiting antibodies to rubella virus as indicators of protective immunity in vaccinees and naturally immune individuals.

In general, hemagglutination-inhibiting (HAI) and neutralizing (NT) antibodies to rubella virus tend to parallel one another, and the presence of either antibody has been interpreted as reflecting protective immunity. It has recently been shown that persons who have HAI antibody but lack NT antibody may be subject to reinfection. In the present study these two antibodies were compared with regard to their appearance and persistence in vaccines and in those who have experienced natural infection. NT antibody appeared more slowly following immunization with HPV77DE5 or Cendehill vaccines than after natural infection or immunization with RA 27/3 vaccine. As with natural infection, initial NT antibody responses to RA 27/3 vaccine were of higher titer and persisted at higher levels for three years than was the case with either of the other vaccines. NT testing procedures were found to differ in sensitivity, depending on several factors including the cells in which the virus was grown.

Fate of rubella genome ribonucleic acid after immune and nonimmune virolysis in the presence of ribonuclease.

To determine whether rubella virion ribonucleic acid (RNA) becomes accessible to nuclease attack after immune lysis of the viral envelope, virions containing radioactively labeled RNA were examined in three ways with the following results. (i) Incubation of purified virus with heat-inactivated rubella convalescent human serum and guinea pig complement resulted in an increase in acid-soluble RNA. Antibody was required; the reaction was temperature dependent and was blocked by ethylenediaminetetraacetic acid. When exogenous nuclease was added prior to lysis, radioactivity in virions was reduced to 15% of that in unlysed control pellets (ii) Sucrose gradient sedimentation profiles of RNA released from lysed and unlysed virions under controlled conditions showed that the nuclease content of serum-virus mixtures was sufficient to eliminate all RNA of genome size, although degradation was not complete. (iii) Virions were also lysed by unheated human immune sera in the absence of guinea pig complement and by some, but not all, unheated antibody-negative sera.

The behavior of a newly described acute-phase protein in inflammatory joint disease.

Rho, a newly characterized acute-phase protein, was present in high titer in a group of 109 patients with various rheumatic diseases. Statistically significant titer elevations were demonstrated in patients with rheumatoid arthritis (RA), ankylosing spondylitis, and gout. In individual RA patients, serial titers failed to correlate with disease activity or with rheumatic seropositivity. The natural behavior ofrho antigen is contrasted with that of C-reactive protein. Comments are made regarding the possible association of rubella infection with rheumatoid arthritis.

The relationship of a newly described acute-phase protein to human gestation.

Rho is a newly described acute-phase serum protein which increases in titer in response to a variety of inflammatory and infectious diseases. It is present in 100 per cent of sera from pregnant women by the twentieth week of gestation, rises in titer until term, and then falls slowly during the postpartum period. It was barely detectable in some fetal sera and in some amniotic fluid samples near the end of the first half of gestation, and it could not be demonstrated in fetal tissue obtained at that time. Fetal serum titers increase with gestational age, but fetal levels remain below those of maternal sera. Undifferentiated placental tissue and estrogen/progestin do not appear to evoke rho antigen production. The stimulating mechanism during gestation remains unknown.

Large-scale production of rubella precipitinogens and their use in the diagnostic laboratory.

A method for producing large quantities of rubella theta and iota precipitating antigens in Vero cells is described. Using this reagent, the detection of anti-theta antibodies was found to be as sensitive as the hemagglutination inhibition test for both the determination of immune status and the diagnosis of acute rubella infection. The detection of anti-iota antibodies may permit diagnosis of rubella infection, when the collection of the first serum has been delayed and the early rise of hemagglutin-inhibiting and anti-theta antibodies has been missed.

Characterization of a human acute phase protein found in association with rubella virus infection.

A precipitating antigen, rho, was first detected in the blood of persons with rubella and in rubella virus-infected cell culture fluids (1). Partially purified antigens from both sources were examined and shown to have similar properties, although antigen from serum sedimented more heterogeneously, with estimated coefficients from 15 to 21 S, while that from culture fluids sedimented in the 11-14 S region. In each case, antigen was located in the beta-1 zone after electrophoresis in agarose, and at a density of 1.305 g/ml after centrifugation in CsCl. Stability characteristics were typical of protein antigens. Immunofluorescent microscopy revealed that rubella virus induced the appearance of rho antigen scattered throughout the cytoplasm of infected cells. When cells containing antigen were exposed for 24 h to 5 microg/ml actinomycin D rho was no longer detectable, indicating the probable cellular origin of the antigen. Also, titers in medium of infected cultures showed a reduction after actinomycin treatment, but levels of the virus-specified antigen, iota, were relatively unaffected. Rho appears to be a protein common to man and many animals. In vitro, it was induced by rubella virus and by adenovirus. In vivo, rho titers were shown to be elevated after rubella virus infection and, to a lesser extent, after infection with certain other viruses. High titers were also demonstrated in women late in pregnancy and in patients with rheumatoid arthritis. In man and the chimpanzee, the appearance and decline of rho in the blood after rubella virus infection were temporally similar to the patterns of CRP, although rho seemed to be a more sensitive indicator of infection. The data presented indicate that rho is a newly recognized acute phase protein inducible by certain virus infections and by other unidentified stimuli present prominently in pregnancy and rheumatoid arthritis.

Actinomycin D; renewed RNA synthesis after removal from mammalian cells.

Suppressed RNA synthesis exceeded control rates 2 hours after removal of actinomycin from serial lines of green monkey kidney cells in exponentially dividing monolayer cultures. Enhanced synthesis was directly related to the dose of actinomycin, and release from inhibition was temperature dependent. A broad range of RNA sizes was made after removal of drug, but cytoplasmic and nucleolar sedimentation profiles were abnormal for at least 20 hours.

Removal of Nonidet P40 absorbance for optical density monitoring of cytoplasmic ribonucleic acid.

Absorbance at 260 nm due to Nonidet P40 in cytoplasmic extracts can effectively be reduced by extraction with CHCl(3) without appreciable loss of ribonucleic acid.