Serum Neutralizing Antibody Levels Research Articles

Mechanism of recovery from systemic infection with vaccinia virus. II. Effects of x-irradiation and neonatal thymectomy.

The effects of X-irradiation and neonatal thymectomy on the recovery of mice from primary systemic infection with vaccinia virus were studied to elucidate the roles of antibody, cellular immunity, and interferon in the recovery process. Mice that received 350 R of X-irradiation had a markedly increased susceptibility to vaccinia virus infection and did not have detectable levels of serum neutralizing antibody to vaccinia virus. Potentiation of this infection by X-irradiation was largely reversed by the passive administration of physiologic amounts of antibody late in the course of infection, at a time when neutralizing antibody was present in the serum of nonimmunosuppressed mice. Neonatally thymectomized mice, on the other hand, formed neutralizing antibody normally and recovered normally from primary vaccinia virus infection. Levels of interferon in serum were not influenced by either of these two methods of immunosuppression.

PROSPECTIVE STUDY OF A MIXED COXSACKIE VIRUS B3 AND B4 OUTBREAK OF UPPER RESPIRATORY ILLNESS IN A CHILDREN'S HOME

In the late summer of 1968 an outbreak of moderately severe upper respiratory illness occurred among the 120 children living in a children's home. Coxsackie viruses B3 and B4 were isolated from throat swabs and eye swabs of 21 children who were clinically ill. Neutralization tests were performed on serum specimens collected from each child before, during, and after the outbreak. Fifty-two percent of the children in the home experienced an infection with B3 or B4, 10% were sequentially infected with both types, and 38% remained uninfected. Coxsackie B3 accounted for 57% of all infections, and B4, for 43%. Infection was clearly related to age, and to preexisting antibody. Preexisting B3 and B4 serum neutralizing antibody levels of 1:20 and greater were fully protective against reinfection by the respective virus type. These viruses caused a wide spectrum of symptoms and physical findings which ranged from inapparent infections to aseptic meningitis. Conjunctivitis, exudative tonsillopharyngitis, otitis, and enanthem, were more frequently associated with B3 than B4, and aseptic meningitis was more frequently associated with B4 than B3. One child, experiencing a distinctly biphasic pattern of illness, exhibited a delayed antibody response concomitant with persistent virus shedding from the throat for a duration of 57 days. Using figures corrected for the effect of protective preexisting antibody, the reported illness rate for Coxsackie B3 in the total population was 24%, and the unreported illness rate was 21%; the ratio was 1:1. For type B4, the reported rate was 18% and the unreported rate 38%, for a 1:2 reported: unreported ratio.

Temperature-sensitive mutants of respiratory syncytial virus: in-vivo studies in hamsters.

Respiratory syncytial (RS) virus is the most important cause of bronchiolitis and pneumonia during infancy and early childhood [1]. For this reason a high priority has been given to the development of a vaccine that could be used to prevent the considerable morbidity and mortality caused by the virus. Initial attempts were directed toward the development of an inactivated, parenterally administered vaccine. Unfortunately, a vaccine of this type, which stimulated high levels of serum neutralizing antibody, did not provide protection against naturally occurring infection [2]. In fact, when infected with RS virus, the vaccinees developed more serious illness than their unvaccinated cohorts [2]. As a result of these experiments, attention has shifted toward the development of viral strains that could be used in a live attenuated vaccine

Serum Neutralization Anti-IgG Test for Psittacosis

Levels of antibodies in sera from patients with diagnoses of subclinical or established psittacosis infections were determined by the serum neutralization anti-IgG test and by conventional tests. Relatively high levels of serum neutralizing anti-bodies were detected in tests in which anti-IgG was used, whereas conventional tests disclosed only marginal levels of antibody. Use of the serum neutralization anti-IgG test in conjunction with the fluorescent cell-counting technique permitted serum antibody determinations within 24 hr.

Antigenic response to influenza virus in man. I. Neutralizing antibody response to inactivated monovalent A2 vaccine as related to prior influenza exposure.

Brown, P., D. C. Gajdusek and J. A. Morris (NIH, Bethesda, Md. 20014). Anti-genic response to influenza virus in man. I. Neutralizing antibody response to inactivated monovalent A2 vaccine as related to prior influenza exposure. Amer. J. Epid., 1969, 90: 327–335.—Isolated Pacific island populations without earlier exposure, or with single exposures to earlier subtypes of influenza, were immunized in 1965 and 1966 with one of 4 inactivated monovalent Influenza A2 vaccines. The majority of previously unexposed subjects developed low levels of serum neutralizing antibody after a single dose of vaccine; the response was often limited to homologous antibody, and in approximately 1/5 of the subjects was slow to develop (higher titers at 7 months than at 4–7 weeks after vaccination). The response was quantitatively less intense but qualitatively similar to the primary response following natural influenza A2 infection. Subjects previously exposed only to an earlier subtype infection responded to a single dose of vaccine somewhat more frequently, rapidly, broadly, and at higher titer than the virgin group. In no subject, however, did the titer to the subtype responsible for the earlier ‘original’ infection exceed or even equal the titer to the homologous vaccine strain. Both virgin and previously exposed subjects exhibited characteristic booster type responses after a second dose of vaccine given 7 months after the first dose. Neither vaccinated nor naturally infected subjects showed any heterologous antibody to the recent A2/Hong Kong/68 variant.

Studies on Induced Influenza in Man

A single double-blind study conducted with 55 volunteers showed clearly that Exp 126 (alpha-methyl-1-adamantanemethylamine hydrochloride, rimantadine hydrochloride), an analogue of amantadine hydrochloride, reduced the occurrence and severity of artificially induced Asian influenza in humans. The infection (or seroconversion) rate in the drug-dosed and placebo-dosed groups was almost 100%, although the increase in serum neutralizing antibody levels was significantly less in the Exp 126-dosed subjects. The infecting influenza virus was recovered only from placebo-dosed controls. Probable untoward reactions from the drug occurred in three volunteers. Two related drugs, amantadine hydrochloride and rimantadine hydrochloride are now available for the prevention of Asian influenza.

Human influenza resulting from aerosol inhalation.

Volunteers were given A2 influenza virus in a small-particle aerosol. Infection and typical influenza resulted from low doses of virus administered in this manner. Low levels of serum neutralizing antibody were not completely effective in preventing infection and illness. The human infectious dose of this influenza strain when administered by aerosol to subjects free of serum neutralizing antibody was approximately 3 TCID50.

Feline Panleucopaenia: I.—Identification of a Virus Associated with the Syndrome

SUMMARY The relationship between a virus isolated from a leopard spleen and the feline panleucopaenia syndrome was investigated. Inoculation of kittens with tissue culture fluids containing leopard virus (LV) produced a syndrome which was indistinguishable from that produced in a comparable group of kittens inoculated with feline panleucopaenia infected tissue, and immunity to cross challenge was established in each group. Susceptibility to challenge in each group was correlated with low levels of serum neutralizing antibody to leopard virus, and resistance to cross challenge with comparable increases in antibody to LV. Agents similar to leopard virus were isolated from the tissues of domestic cats naturally infected with feline panleucopaenia and evidence of a relationship between the agents was obtained by comparative serological and cytopathic studies. It is concluded that the agent isolated from the leopard spleen is similar to that involved in the feline panleucopaenia syndrome in domestic cats, and in all probability is the basic cause of the syndrome.