We studied the mechanism of lymphocytic choriomeningitis virus (LCMV) persistence and the suppression of cytotoxic T lymphocyte (CTL) responses in BALB/c WEHI mice infected at birth with LCMV Armstrong strain. Using adoptive transfer experiments we found that spleen cells from persistently infected (carrier) mice actively suppressed the expected LCMV-specific CTL response of spleen cells from normal adult mice. The suppression was specific for the CTL response and LCMV -specific antibody responses were not affected. Associated with the specific CTL suppression was the establishment of persistent LCMV infection. The transfer of spleen or lymph node cells containing LCMV -specific CTL resulted in virus clearance and prevented establishment of the carrier state. The suppression of LCMV -specific CTL responses by carrier spleen cells is not mediated by a suppressor cell, but is due to the presence of genetic variants of LCMV in spleens of carrier mice. Such virus variants selectively suppress LCMV-specific CTL responses and cause persistent infections in immunocompetent mice. In striking contrast, wild-type LCMV Armstrong, from which these variants were generated, induces a potent CTL response in immunocompetent mice and the LCMV infection is rapidly cleared. Our results show that LCMV variants that emerge during infection in vivo play a crucial role in the suppression of virus-specific CTL responses and in the maintenance of virus persistence.

To determine the usefulness of nasal swabs as a simple method for detection of respiratory viruses, we compared nasal swabs and nasopharyngeal aspirates obtained at the same time from the opposite nostrils of 230 children with upper respiratory infection. The sensitivity of nasal swabs was comparable to that of nasopharyngeal aspirates for the detection of all major respiratory viruses except respiratory syncytial virus

Monoclonal hybridoma antibodies (MAb) of defined polypeptide specificity and biological activity were used in a competition binding assay to identify antibody binding sites (epitopes) on the glycoproteins of murine hepatitis virus-4 strain JHM (MHV-4). Individual MAb were labeled with horseradish peroxidase (HRP) and used as probes in a competition enzyme immunoassay (EIA). Four topographically distinct antigenic sites were detected on the E2 glycoprotein of MHV-4. Antibodies reacting with these four determinants provisionally designated A(E2), B(E2), C(E2), and D(E2) had corresponding biological activities (M. J. Buchmeier, H. A. Lewicki, P. J. Talbot, and R. L. Knobler (1984) Virology 132, 261-270). Antibodies to sites A(E2) and B(E2) mediated virus neutralization in vitro and passively protected mice against lethal virus challenge in vivo. Antibody to site C(E2) neutralized virus efficiently in vitro but did not alter disease in vivo, while antibody to site D(E2) neither neutralized nor protected. Two major nonoverlapping antigenic sites were defined on the E1 glycoprotein. Overlapping epitopes A(E1) and B(E1) constituted one site and epitope C(E1) the other.

Four-layer antispecies radioimmunoassay (RIA) and enzyme immunoassay (EIA) procedures were developed for the detection of respiratory syncytial virus (RSV), parainfluenza type 2 virus, and adenovirus antigens in nasopharyngeal specimens from children hospitalized for acute respiratory disease. Polystyrene beads (RIA) or flat-bottomed polystyrene microtiter plates (EIA) were used as the solid phases, guinea pig anti-virus immunoglobulin were used as the captive antibodies, rabbit anti-virus immunoglobulin were used as the secondary antibodies, and '25I-labeled sheep anti-rabbit (RIA) or horseradish peroxidase-labeled

Failure to seroconvert (primary vaccine failure) is believed to be the principal reason (approx. > 95%) why some vaccinees remain susceptible to measles and is often attributed to the persistence of maternal antibodies in children vaccinated at a young age. Avidity testing is able to separate primary from secondary vaccine failures (waning and/or incomplete immunity), but has not been utilized in measles epidemiology. Low-avidity (LA) and high-avidity (HA) virus-specific IgG antibodies indicate primary and secondary failure, respectively. Measles vaccine failures (n = 142; mean age 10.1 years, range 2-22 years) from an outbreak in 1988-9 in Finland were tested for measles-virus IgG avidity using a protein denaturating EIA. Severity of measles was recorded in 89 failures and 169 non-vaccinees (mean age 16.2 years, range 2-22 years). The patients with HA antibodies (n = 28) tended to have clinically mild measles and rapid IgG response. Among failures vaccinated at < 12, 12-15 and > 15 months of age with single doses of Schwarz-strain vaccine in the 1970s, 50 (95% CI 1-99), 36 (CI 16-56) and 25% (CI 8-42) had HA antibodies, respectively. When a single measles, mumps and rubella (MMR) vaccine had been given after 1982 at 15 months of age, only 7% (CI 0-14) showed HA antibodies. Omitting re-vaccinees and those vaccinated at < 15 months, Schwarz-strain recipients had 3.6 (CI 1.1-11.5) higher occurrence of HA responses compared to MMR recipients. Apart from one municipality, where even re-vaccinees had high risk of primary infection, 89% (CI 69 to approximately 100) of the infected re-vaccinees had an HA response. Secondary measles-vaccine failures are more common than was more previously thought, particularly among individuals vaccinated in early life, long ago, and among re-vaccinees. Waning immunity even among individuals vaccinated after 15 months of age, without the boosting effect of natural infections should be considered a relevant possibility in future planning of vaccination against measles.

Young children in a day care setting had a high rate of shedding and a low rate of transmission. No clinically significant illness occurred among children who received vaccine or placebo or in the child to whom the vaccine virus was transmitted.

Multiple sclerosis (MS) and matched control sera had similar antibody titers to coronaviruses OC43 and 229E when tested by a radioimmunoassay method. In contrast, cerebrospinal fluid from MS patients contained coronavirus antibodies more frequently and in higher titers than matched controls. Intrathecal antibody synthesis to OC43 and 229E viruses was detected in 41% (9/22) and 26% (7/27) of MS patients, respectively, but was not found in any of the neurologic control patients. This intrathecal antibody synthesis may mean that coronaviruses play an etiologic or pathogenic role in MS. Alternatively, intrathecal synthesis of coronavirus antibodies may be but part of a generalized and variable intrathecal antibody synthesis that is typical for MS patients.

The occurrence of a local production in the central nervous system (CNS) of antibodies against different selected viruses was analyzed by comparison of titers in serum and cerebrospinal fluid samples from groups of 50 patients with multiple sclerosis from Finland, Norway, and Sweden. Measles antibodies were determined in hemagglutination inhibition, hemolysis inhibition, and nucleocapsid complement fixation tests; mumps, parainfluenza virus type 1, and rubella virus antibodies were determined in hemagglutination inhibition tests; and herpes simplex virus type 1 antibodies were determined in passive hemagglutination tests. For reference purposes tests were also made for adenovirus antibodies in penton hemagglutination enhancement tests and poliovirus antibodies in neutralization enhancement tests. Among the 150 multiple sclerosis patients, a local production of antibodies against measles virus was found in the CNS in 57%, against rubella virus in 19%, mumps virus in 15%, herpes simplex virus type 1 in 11%, and parainfluenza virus type 1 (Sendai) in 3T. A local production in the CNS of antibodies against any of the viruses studied was found in 71% of multiple sclerosis patients. These included 48, 16, and 7% that produced antibodies to one, two, and three or more viruses, respectively.