Routine use of mu-antibody-capture ELISA for the serological diagnosis of Coxsackie B virus infections.

The role of coxsackie B viruses (CBV) in myo/pericarditis has been well documented; however, interpretation of static high neutralising antibody titres in individual patients has always been difficult. In introducing the mu-antibody capture ELISA test for the detection of CBV-specific IgM, we hoped to overcome this problem. A regimen for the routine serological diagnosis of CBV infections was introduced, using the CBV IgM ELISA as a screening test, followed by neutralisation tests (NT) to confirm the positive results. Seven hundred and sixty patients and 304 healthy adult controls were tested. The percentage CBV IgM positive in each of the clinical categories myo/pericarditis (33%) chest pain (22%), myalgic encephalomyelitis (31%), myalgia/Bornholm (19%) and controls (9%) was similar to those found in previous studies using NT alone. Cross-reactions with other enteroviruses, including hepatitis A (Enterovirus 72), were observed but did not prove to be a problem in the illness studied, since most involved adults. Both homotypic and heterotypic CBV IgM responses were found. Matching IgM and NT indicated a recent CBV infection. Positive IgM with negative NT titres suggested a recent infection with an enterovirus other than a CBV.

Does fever or myalgia indicate reduced physical performance capacity in viral infections?

To study prospectively the effects of a brief febrile viral infection on parameters of muscle and circulatory function, seven volunteers were inoculated with sandfly fever virus and two control subjects with sterile saline. During but not after fever, decreased isometric and dynamic strength and endurance were recorded in various muscles. Impairment could not be explained by altered activities of relevant muscle enzymes in serum or muscle tissue or by altered muscle ultrastructure, but correlated with the severity of perceived symptoms, including myalgia, as rated by each subject. Compared to baseline, cardiac stroke volume was lower during and after fever. During fever, an increased heart rate maintained cardiac output at pre-inoculation values, whereas cardiac output fell in early convalescence. This decrease in cardiac output correlated significantly with the severity of fever. Thus, in brief viral infections a transient impairment of muscle performance capacity is correlated to subjective symptoms such as myalgia, rather than to fever, whereas a decreased cardiac output following such infections seems to be associated with the fever reaction.

Coxsackie-B-virus-specific IgM responses in patients with cardiac and other diseases.

An enzyme-linked immunosorbent assay (ELISA) test using polyvalent antigens and antisera was developed to detect Coxsackie-B-virus-specific IgM responses. The sera of 24 of 64 (37.5%) patients with acute pericarditis and 14 of 38 (36%) with acute myocarditis were positive for Coxsackie-B-virus-specific IgM. 4 of 30 (13.3%) patients with acute ischaemic heart disease and 2 of 28 (7.1%) patients with congestive cardiomyopathy were also positive. Coxsackie-B-virus-specific IgM was detected in the sera of 21 of 57 (36.8%) patients with Bornholm disease and 2 of 4 patients with acute-onset juvenile diabetes. Coxsackie-B-virus-specific IgM responses persisted for 6-8 weeks. Sera from patients with chronic valvular heart disease, Mycoplasma pneumoniae infections, and virus infections caused by viruses other than Coxsackie-B viruses were all negative. False-positive results did not occur when sera containing high titres of rheumatoid factor were tested.

The role of coxsackie B viruses in heart disease in New Zealand.

Sera from 622 patients received in a 20-month period were examined for coxsackie B neutralising antibody to serotypes 1--6. Two hundred and thirty-four of the total 622 were patients with a cardiac symptomatology, and 388 formed a comparable group of non-cardiac cases. There were 141 (60 percent) seropositive patients in the cardiac group, 34 percent and 29 percent of which respectively had antibody to B4 and B2. The clinical data provided on these 141 patients indicated that 33 (23 percent) had acute myocarditis, and 59 (42 percent) had acute pericarditis; 41 (29 percent) were recorded as having acute pleurodynia or Bronholm disease while eight (6 percent) had other indications of cardiac disease. Amongst the cardiac patients the highest prevalence of seropositivity was found in the 20--39 age group and 67 percent of these were males.