Decline In Antibody Titers Research Articles

Isolation of Pasteurella haemolytica and correlation with serum antibody response in clinically normal beef calves

Bacteria from the nasal cavity and trachea were cultured, and serum antibody titers determined for Pasteurella haemolytica serotype 1 in 164 beef calves obtained from a closed herd on range pasture. At the first sampling, P. haemolytica serotype 1 was cultured from 16.4% of the calves. Antibody titers were determined by a quantitative fluorimetric method and the mean titer was 9.5 ± 5.8. Fifty-seven randomly selected calves were used to study the correlation of serum antibody response and positive culture of P. haemolytica under natural conditions. Clinical signs of respiratory disease were not observed in those calves. During the observation periods, there was a two-fold increase in the percentage of calves that were culture positive. There was no significant difference between mean serum antibody titers or frequency distribution of antibody titers from the two samplings. Comparisons between serum antibody titers, rise in titers, and P. haemolytica isolation failed to reveal any significant correlation. Of the 9 calves that had a decline in antibody titer to P. haemolytica, none was culture positive. Seroconversion to respiratory viruses did not correlate with P. haemolytica related variables.

Fasciola hepatica: antibody levels in sheep serum before and after treatment with anthelmintic

Two groups of sheep were treated with the anthelmintic diamphenithide three and six weeks respectively after oral infection with metacercariae of Fasciola hepatica. A third group was infected but left untreated. The levels of circulating antibody against three parasite antigens Tl (juvenile tegument glycocalyx). T2 (adult tegument) and G (gut secretions) were monitored throughout infection and recovery-periods using an indirect fluorescent antibody technique with serial sections of plastic-embedded fluke tissues as test antigen. Termination of infection after three weeks prevented the development of the T2 antibody response and led to significant premature peaking and, or, decline of Tl and G antibodies. However the magnitude of these peaks was unaffected by chemotherapy. Treatment six weeks after infection had no significant effect on the Tl or G antibody titres and these antibody profiles closely resembled the equivalents in control animals. However the T2 antibody response was somewhat reduced, supporting the view that while T2 granules occur in the tegumental syncytium from an early stage in fluke development the T2 antigens are not expressed at the surface until late in the liver migration phase. In the three week and six week treated groups, decline from peak antibody titres during the recovery period paralleled natural decline in antibody titres after bile duct invasion in the untreated control animals. This provides evidence for immunological isolation of the bile duct habitat.

A rift Valley fever vaccine trial. I. Side effects and serologic response over a six-month follow-up.

A formalin-inactivated Rift Valley fever vaccine, originally produced in primary monkey kidney cells, has been used to protect laboratory workers. A trial of a modified vaccine, newly formulated in well-characterized diploid fetal rhesus lung cells, was conducted with 114 men aged 19--24 years. Of the 107 subjects who received up to three injections of 0.1 to 1 ml vaccine (an additional seven received a placebo) one had a local hypersensitivity-type reaction and another a generalized urticarial syndrome. Both cases had a prior history of hypersensitivity states. No pyrogenicity was detected and only insignificant systemic reactions were recorded. Mild and transient local reactions ranged from 5% at the lowest dose level to 43% at the highest. Serologic response, as assessed by plaque reduction neutralizing antibody titers, was dose dependent. Within a single vaccine lot tested at multiple dose levels, peak (day 42) geometric mean titers ranged from 48 (at 0.1 ml x 3) to 436 (at 1.0 ml x 3). Reciprocal titers of greater than or equal to 40 are considered to be protective. Comparison of three lots at the 0.5 ml level indicated between lot variability, though this was not statistically significant. A sharp decline in antibody titers was observed in all vaccination groups by day 84; six months after vaccination apparently protective antibody titers were present only in groups that received 1 ml x 3 and 0.5 ml x 3 of the most antigenic lot of vaccine. These results suggest that 1) the vaccine is generally nonreactogenic, but individuals with a prior history of hypersensitivity states should be observed for allergic side effects; 2) existing vaccine supplies cannot be extended by using lower dose levels without a lower and less sustained serologic response; 3) a booster dose is necessary six months or more following the primary series; 4) although the current TSI-GSD-200 vaccine is immunogenic, a more potent vaccine is needed.

LONG-TERM EFFECTS OF REPEATED PLASMA EXCHANGE IN MYASTHENIA GRAVIS

Plasma exchange produces a short-term clinical improvement in myasthenia gravis (M.G.) which may be attributable to removal of acetylcholine receptor (AChR) antibody. The possibility that repeated plasma exchanges might confer cumulative long-term benefits was investigated. Serum-AChR-antibody and clinical response were followed for 4-12 months (mean 8 months) in six M.G. patients receiving 4-25 plasma exchanges of 2-4 1 together with immunosuppressive drugs (azathioprine [2·5 mg/kg] with or without alternate-day prednisone therapy), and in seven M.G. patients on immunosuppressive drugs alone. Percentage decrease in AChR antibody was not significantly different in the two treatment groups. Decline in antibody titre was associated with clinical improvement. Eight patients with previous thymoma showed significantly greater decline in antibody than the remaining five patients, irrespective of plasma exchange. Since repeated plasma exchange had no cumulative long-term benefit, the value of this treatment as used here lies only in short-term control of severe M.G. symptoms.

Social interactions and antibody titres in young male chickens ( Gallus domesticus)

The influence of social interactions on established antibody titres to a Salmonella pullorum antigen was determined in several Athens Randombred families. In two experiments, a large-bodied, aggressive family and a small-bodied, relatively non-aggressive family were placed in three social environments: (1) Four-bird control groups with no changes in membership once formed; (2) three-bird resident groups to which a new fourth bird was introduced daily; (3) the single bird that had been moved to a new group each day. The normal rate of decline in antibody titres was significantly accelerated in birds that were introduced as new members daily (group 3), but only in members of the small non-aggressive family. In a third experiment, using families relatively close in size and aggressiveness, the effects of social grouping on antibody titres were not significant.

Persistence of measles antibody after immunization

The authors followed up the persistence of measles antibodies at 1-year intervals in children given three different live attenuated measles vaccines. The best results were obtained in a group of children given the attenuated Schwarz strain vaccine; this vaccine, prepared in chick embryo cells, consistently produced sero-conversion rates of 92% over a period of 2–6 years. The lowest sero-conversion rate was observed in children given the Edmonston strain vaccine prepared on dog-kidney cells; here, the vaccine induced a sero-conversion rate of 66% after 5–6 years following the immunization. Proportions of seronegative children in three groups of children, administered the Schwarz strain vaccine, prepared on dog-kidney cells, were shown to vary; nevertheless, no statistically significant differences among these groups could be demonstrated. The average sero-conversion rates in the three groups of children were 97, 91, 85 and 82% following 1, 2, 3 and 4 years after immunization, respectively. The greatest decline in antibody titre was shown to occur between 1 month and 1 year after vaccination. In subsequent years these values may vary.

Plague immunization. 3. Serologic response to multiple inoculations of vaccine.

Studies with sera collected during a 20-year period from 117 individuals who received multiple inoculations of plague vaccine, USP, revealed three patterns of serologic response. Eighty-four individuals responded with high titers of indirect hemagglutinating antibody, 23 produced intermediate antibody titers, and 10 did not produce significant antibody titers. After approximately five booster inoculations, each individual attained a plateau level of antibody that remained constant regardless of subsequent administration of booster inoculations. Long-term intervals between booster inoculations did not result in a marked decline in antibody titers. Following suspected episodes of exposure to virulent Yersinia pestis, antibody titers of 29 individuals increased abruptly but returned to previously established plateau levels within 18 months.

Suppression of an Antibody to Factor VIII by a Combination of Factor VIII and Cyclophosphamide

Abstract A 54-year-old woman with a 20-year history of generalized, severe psoriasis presented with diffuse ecchymoses, melena, and vaginal bleeding. The whole blood clotting time was 59 minutes and the plasma factor VIII concentration was less than 1 per cent of normal. Incubation of the patient’s plasma with cryoprecipitate containing one unit of factor VIII resulted in the rapid disappearance of factor VIII activity from the mixture. The major antifactor VIII activity of the patient’s plasma was associated with an immunoglobulin of the IgG class. The patient was initially treated with a combination of methotrexate, azathioprine, and cyclophosphamide. No improvement occurred, and after 6 weeks of therapy the drugs were discontinued. Eight months later, she presented with an expanding sublingual hematoma. Bleeding was controlled by the rapid administration of 10,000 units of factor VIII, and an intravenous dose of cyclophosphamide given concurrently resulted in a prompt decline in antibody titer. Factor VIII levels subsequently became normal and have remained normal during 7 months of follow-up observation.