Mean Serum Antibody Titers Research Articles

Detection of immune effects of the Mannheimia haemolytica gamma irradiated vaccine in sheep.

Exposure to gamma rays from cobalt 60 (Co60) can induce a complete inactivation of Mannheimia haemolytica. The inactivated bacterial pathogen is a potential vaccine candidate for immunization of ruminants such as sheep. The subcutaneous administration of irradiated vaccine in a two-dose regimen (4.0 × 109 colony forming unit (CFU) per dose) results in no mortality in any of the vaccinated sheep during immunization and after subsequent challenge of the live bacteria of the same strain of M. haemolytica. A significant rise in serum IgG titer, detected through ELISA, is observed after the passage of two weeks from the inoculation of the first dose whereas, the peak of the mean serum antibody titer occurred after two weeks of booster dose. The vaccination does not bring significant change to the IFN-γ levels in serum. The bacterial challenge of the vaccinated sheep does not induce a further seroconversion relative to serum antibody titer. In conclusion, the vaccinated sheep are protected by the elevated IgG titer and increased levels of IL-4 (Th-2 response) compared to the non-vaccinated sheep. Radiation technology can provide the opportunity for mass production of immunologically safe vaccines against animal and zoonotic diseases. Ethics Approval by the National Research Center Ethics Committee (Trial Registration Number (TRN) no 13,602,023, 13/5/2023) was obtained.

Local and Systemic Antibody Responses in Beef Calves Vaccinated with a Modified-Live Virus Bovine Respiratory Syncytial Virus (BRSV) Vaccine at Birth following BRSV Infection.

Maternal antibodies interfere with BRSV vaccine responses and efficacy in young calves. The objective of this study was to determine if vaccination before the complete absorption of colostral antibodies results in adequate immune priming and clinical protection of beef calves. Within 6 h of life, calves were randomly assigned to 2 different treatment groups. Group Vacc (n = 25) received a single dose of a modified-live virus (MLV) BRSV vaccine intranasally (IN) and group Control (n = 25) received 2 mL of 0.9% saline IN. At approximately 3 months of age, all calves were experimentally challenged with BRSV. Serum and nasal secretion samples were collected before and after challenge for BRSV real-time RT-PCR and antibody testing. Respiratory signs were not observed before challenge. After challenge, respiratory scores were similar between groups. On the challenge day, >40% of calves in each group were febrile. The mean serum and nasal BRSV-specific antibody titers indicated natural BRSV exposure before the experimental challenge in both groups. All calves tested positive for BRSV and had a similar duration of shedding after challenge. Based on these results, vaccination at birth does not offer advantages for immune priming or clinical protection for beef calves in BRSV-endemic cow-calf herds.

Immunogenicity and protective efficacy of recombinant alkaline shock protein 23 from Staphylococcus aureus in a murine model.

The diversity and severity of infections caused and the rapid emergence of antibiotic resistance necessitates the development of a vaccine against Staphylococcus aureus. None of the antigens tried as vaccine candidates so far has been translated into a clinically viable vaccine. Recent research data suggest that antigens with the potential to activate cell mediated immunity along with humoral immunity would be the key to the development of a vaccine. Alkaline shock protein 23, a membrane-anchored protein involved in the stress response, has been identified as a CD4+ T cell antigen from S. aureus. In the present study, we report the evaluation of immunogenicity and protective efficacy of a recombinant alkaline shock protein 23 from S. aureus in mouse models. The gene coding for the protein was cloned and expressed in Escherichia coli, purified using immobilized metal iron affinity chromatography, sequence-confirmed using mass spectrometry and intraperitoneally administered to BALB/c mice. Serum titers of IgG, IgG1, and IgG2a in response to the protein were measured on post-immunization days 21, 35 and 42 using indirect ELISA and compared to control mice injected with PBS. Our results showed that the protein induced significantly higher (p < 0.01) antibody responses in immunized mice compared to the control mice. The mean serum antibody titers of IgG, IgG1 and IgG2a three weeks after the last immunization were found to be 25600, 25600 and 12800 respectively. Moreover, we found that immunization with Asp23 protected mice from a lethal dose of S. aureus strain USA300.

Assessment of immune response to a lyophilized peste-des-petits-ruminants virus vaccine in three different breeds of goats.

Aim:Immune response to a lyophilized peste-des-petits-ruminants virus (PPRV) vaccine was evaluated in three different breeds of goats.Materials and Methods:Three breeds of goats consisting six number of animals in three groups, i.e., Group A (local Assam hill goat), Group B (cross-bred), and Group C (Beetal goats) were randomly selected for evaluating the immune response to a lyophilized PPRV vaccine.Results:A higher rise in the overall mean serum antibody titer was observed in Group A (40.50±3.74) than in Group B (37.58±37.58) and Group C (35.90±3.29) during the study period.Conclusion:Initially, a negative PPRV specific serum antibody titer was recorded in all the groups at 0th day of vaccination. Serum antibody titer in the vaccinated goats started rising gradually from the 14th day post vaccination. Later higher rise in the overall mean serum antibody titer in Group A (local Assam hill goat) lead to the conclusion that higher serum antibody titer in local non-descript breed might be due to their better adaptation to the environmental condition.

Effect of supplementation of different levels of selenium as nanoparticles/sodium selenite on blood biochemical profile and humoral immunity in male Wistar rats

Aim: To study the effect of supplementation of different levels of selenium as nanoparticles/sodium selenite on blood biochemical profile and humoral immunity in male Wistar rats. Materials and Methods: The experimental research was conducted at Division of Animal Nutrition, Indian Veterinary Research Institute, Izatnagar. 63 male Wistar rats were divided into 9 equal groups on the basis of their mean body weight (BW) (124.3±3.1 g BW) following completely randomized design. Experimental feeding was similar in all the groups except for the source and level of selenium (Se) in the diet. While Group 1 (control) was fed a basal diet with no Se supplementation, in Groups 2 and 3, 150 ppb Se was supplemented either as sodium selenite or Se nanoparticles, respectively. In Groups 4, 5, 6 and 7, Se was supplemented as its nanoparticles at 50%, 25%, 12.5% and 6.25% levels respectively i.e. at 75 ppb, 37.5 ppb, 18.75 ppb and 9.375 ppb levels respectively. In Groups 8 and 9, 300 ppb Se was supplemented either as Se nanoparticles or sodium selenite, respectively. Experimental feeding was conducted for a period of 91 days. At the end of the experimental trial, blood samples were collected to analyze the blood serum biochemical profile (serum glucose, serum total protein (TP), serum albumin, serum globulin, serum albumin: globulin ratio [A:G ratio], serum total cholesterol) and humoral immunity. Results: The levels of serum glucose, serum TP and serum albumin were comparable (p>0.05) among the nine groups of male Wistar rats. The mean serum total cholesterol was significantly (p<0.001) lowered in all the Se supplemented Wistar rats compared to the control group. The mean serum globulin level was significantly (p<0.05) higher and A:G ratio was significantly (p<0.05) lowered in Group 3 (supplemented with 150 ppb selenium nanoparticles) followed by Groups 2, 4, 5, 6, 8, and 9 as compared to the control group. The mean serum antibody titer was significantly (p<0.001) higher in all the Se supplemented groups with the highest value in Group 3 (supplemented with 150 ppb selenium nanoparticles) followed by Groups 4, 5, 8 and 9 compared to the control group. Conclusion: Supplementation of selenium nanoparticles at the level of 150 ppb gave the best performance in terms of increased serum globulin level, reduced A:G ratio, and improved humoral immune status in male Wistar rats.

Effect of Sangrovit on Performance and Morphology of Small Intestine and Immune Response of Broilers

This study was designed to investigate the effects of Sangrovit on performance, small intestinal morphology, and immune response of 300 commercial hybrid broilers, Ross 308. The study was conducted in the Agricultural Research Station of Islamic Azad University, Varamin, in the spring 2010 for 42 days. The broilers were kept in a completely randomized design with 3 treatments, 4 replicates, 12 experimental units each containing 25 broilers. Treatments used in this experiment included controls, 0.05 % and 0.1 % Sangrovit of total ration. The test results showed no significant difference between different treatments during the breeding period on feed intake, feed conversion, and small intestinal morphology. However, treatments containing 0.1% Sangrovit showed significant differences on weight gain in the early rounds between the other treatments (P<0.05). Statistically, these differences were not significant during the breeding period. Regarding the effects of different treatments on the carcass components, the diet containing 0.05% Sangrovit could significantly increase the weight of the thigh (P<0.05) than the other diets. In this treatment, the mean serum antibody titers against Newcastle disease by HI method showed significant differences at 35 and 42 days of the breeding period (P<0.05). Based on the results of this experiment, Sangrovit can obtain the desired results in improving immune system, performance and carcass yield.

A dose–response evaluation of inactivated influenza vaccine given intranasally and intramuscularly to healthy young adults

Epidemic influenza occurs annually throughout the world and is accompanied by excess morbidity and mortality. Increasing the antigen content and topical administration of vaccine are two strategies being explored to improve the immune responses to trivalent inactivated influenza vaccine (TIV). We conducted a randomized, double-blind, placebo-controlled trial to compare the immunogenicity and reactogenicity of intramuscular (IM), intranasal (IN), or combined IM and IN administration of a contemporary US vaccine formulation at escalating dosage levels in young healthy adults. Two hundred forty three healthy adults between the ages of 18 and 45 years received 15, 30, or 60mcg of trivalent inactivated influenza vaccine by either IN, IM or both routes, 120mcg of vaccine IM, or placebo IN and IM. All dosages and routes of vaccine administration were well-tolerated. A bad taste and mild nasal discomfort were more likely to be reported when influenza vaccine was administered IN, while arm tenderness was more common after IM administration. Significant increases in geometric mean serum antibody titers in both HAI and Nt assays were seen in all of the groups receiving influenza vaccine for all test antigens (P<or=.025, paired t-test), except for the B HAI antibody titer in the group that received 30mcg IN (P=.055, paired t-test). Postvaccination geometric mean serum antibody titers, the frequency of seroresponses, and the percentage achieving postvaccination serum HAI antibody titers of >or=32 were higher following delivery of the study vaccines by an IM route than by the IN route, but significant increases in serum antibody were seen after IN vaccination. Nasal IgA antibody responses were more common when vaccine was administered IN; and, when the IN dosage was increased, the primary benefit from IN vaccine over IM vaccine appeared to be greater induction of nasal secretory antibody.

Phase I Evaluation of Intranasal Trivalent Inactivated Influenza Vaccine with Nontoxigenic Escherichia coli Enterotoxin and Novel Biovector as Mucosal Adjuvants, Using Adult Volunteers

Trivalent influenza virus A/Duck/Singapore (H5N3), A/Panama (H3N2), and B/Guandong vaccine preparations were used in a randomized, controlled, dose-ranging phase I study. The vaccines were prepared from highly purified hemagglutinin and neuraminidase from influenza viruses propagated in embryonated chicken eggs and inactivated with formaldehyde. We assigned 100 participants to six vaccine groups, as follows. Three intranasally vaccinated groups received 7.5-microg doses of hemagglutinin from each virus strain with either 3, 10, or 30 microg of heat-labile Escherichia coli enterotoxin (LTK63) and 990 microg of a supramolecular biovector; one intranasally vaccinated group was given 7.5-microg doses of hemagglutinin with 30 microg of LTK63 without the biovector; and another intranasally vaccinated group received saline solution as a placebo. The final group received an intramuscular vaccine containing 15 microg hemagglutinin from each strain with MF59 adjuvant. The immunogenicity of two intranasal doses, delivered by syringe as drops into both nostrils with an interval of 1 week between, was compared with that of two inoculations by intramuscular delivery 3 weeks apart. The intramuscular and intranasal vaccine formulations were both immunogenic but stimulated different limbs of the immune system. The largest increase in circulating antibodies occurred in response to intramuscular vaccination; the largest mucosal immunoglobulin A (IgA) response occurred in response to mucosal vaccination. Current licensing criteria for influenza vaccines in the European Union were satisfied by serum hemagglutination inhibition responses to A/Panama and B/Guandong hemagglutinins given with MF59 adjuvant by injection and to B/Guandong hemagglutinin given intranasally with the highest dose of LTK63 and the biovector. Geometric mean serum antibody titers by hemagglutination inhibition and microneutralization were significantly higher for each virus strain at 3 and 6 weeks in recipients of the intramuscular vaccine than in recipients of the intranasal vaccine. The immunogenicity of the intranasally delivered experimental vaccine varied by influenza virus strain. Mucosal IgA responses to A/Duck/Singapore (H5N3), A/Panama (H3N2), and B/Guandong were highest in participants given 30 microg LTK63 with the biovector, occurring in 7/15 (47%; P=0.0103), 8/15 (53%; P=0.0362), and 14/15 (93%; P=0.0033) participants, respectively, compared to the placebo group. The addition of the biovector to the vaccine given with 30 microg LTK63 enhanced mucosal IgA responses to A/Duck/Singapore (H5N3) (P=0.0491) and B/Guandong (P=0.0028) but not to A/Panama (H3N2). All vaccines were well tolerated.

Effect of vaccination against leptospirosis on the frequency, days to recurrence and progression of disease in horses with equine recurrent uveitis

To evaluate the effect of vaccination against leptospirosis on frequency and days to recurrence of uveitis and progression of disease in horses with equine recurrent uveitis (ERU). Forty-one horses with ERU. Horses were randomly assigned to experimental (vaccinated) or control groups. Vaccine containing six serovars of Leptospira or placebo was administered, an ophthalmic examination performed and blood samples drawn on days 0, 28, 180 and 365. Antibody titers were measured against each serovar. Recurrence of uveitis was verified by ophthalmic examination. Results of the initial and final ophthalmic examinations were compared and progression of disease defined as an increase in extent of synechiae, or development of new or progression of an existing cataract. Vaccination increased the average geometric mean serum antibody titer from 225 on day 0, to 4077 and 593 on days 28 and 180, respectively. After the second vaccination, days to first recurrence was significantly longer (median 126 days; range 24-231 days) when compared with controls (median 86 days; range 14-192 days, P=0.04). Recurrence of ERU was observed among 7/20 (35%) vaccinated horses and 12/21 (57%) controls; however, this difference was not statistically significant (P=0.061, OR 0.25, 95% CI 0.06, 1.07). More horses in the experimental group 13/20 (65%) experienced progression of disease when compared with controls 12/21(57%); however, this difference was statistically nonsignificant (P=0.35). Vaccine significantly increased days to recurrence, but failed to slow the progression of disease. These data do not support the use of vaccination against leptospirosis as adjunct therapy for the routine treatment of horses with ERU.

Intranasal immunization with multivalent group A streptococcal vaccines protects mice against intranasal challenge infections.

We have previously shown that a hexavalent group A streptococcal M protein-based vaccine evoked bactericidal antibodies after intramuscular injection. In the present study, we show that the hexavalent vaccine formulated with several different mucosal adjuvants and delivered intranasally induced serum and salivary antibodies that protected mice from intranasal challenge infections with virulent group A streptococci. The hexavalent vaccine was formulated with liposomes with or without monophosphorylated lipid A (MPL), cholera toxin B subunit with or without holotoxin, or proteosomes from Neisseria meningitidis outer membrane proteins complexed with lipopolysaccharide from Shigella flexneri. Intranasal immunization with the hexavalent vaccine mixed with these adjuvants resulted in significant levels of antibodies in serum 2 weeks after the final dose. Mean serum antibody titers were equivalent in all groups of mice except those that were immunized with hexavalent protein plus liposomes without MPL, which were significantly lower. Salivary antibodies were also detected in mice that received the vaccine formulated with the four strongest adjuvants. T-cell proliferative assays and cytokine assays using lymphocytes from cervical lymph nodes and spleens from mice immunized with the hexavalent vaccine formulated with proteosomes indicated the presence of hexavalent protein-specific T cells and a Th1-weighted mixed Th1-Th2 cytokine profile. Intranasal immunization with adjuvanted formulations of the hexavalent vaccine resulted in significant levels of protection (80 to 100%) following intranasal challenge infections with type 24 group A streptococci. Our results indicate that intranasal delivery of adjuvanted multivalent M protein vaccines induces protective antibody responses and may provide an alternative to parenteral vaccine formulations.

Periodontal status and serum antibody titers for Porphyromonas gingivalis fimbriae in a rural population in Japan.

The present study was undertaken to assess the periodontal status of a rural Japanese population and to study the correlation between the periodontal status and the serum antibody titers for Porphyromonas gingivalis (Pg) fimbriae. A total of 236 individuals were examined for their periodontal conditions by the use of the community periodontal index for treatment needs (CPITN), and serum antibody titers for Pg fimbriae in their peripheral blood samples were evaluated using the enzyme-linked immunosorbent assay. There was a substantially larger proportion of edentulous subjects in the age group older than 60 years. The remaining teeth were 24.1, 23.2, 11.1 and 10.1 per person in the 40-49, 50-59, 60-69 and > or = 70 age groups, respectively. The % of sextants with a CPITN code of missing sextant (MS) increased towards elderly and reached >60% in the age group of > or = 70 years, as the % of the CPITN 2, 1 or 0 sextant decreased. The % of CPITN 4 and 3 sextants did not differ between different age groups and were about 6-8% and 15-20%, respectively. The % of CPITN 1 or 0 sextants was higher in female subjects than in male subjects in the 60-69 and > or = 70 age groups, while the % of CPITN 4 or 3 sextants was higher in male subjects than in female subjects in all age groups. There was no significant difference between various age groups in the mean serum antibody titers for Pg fimbriae. The mean anti-Pg fimbriae antibody titers was significantly higher for the subjects with a maximum CPITN code 4 (max.-CPITN 4 subject) than for the subjects with lower maximum CPITN codes. The antibody titers varied extensively among the max.-CPITN 4 or 3 subjects, but not among the max.-CPITN 2/1/0 or MS subjects. The present study demonstrated that tooth loss is a remarkable event in elderly subjects and that oral prophylaxis and mechanical debridement should be mandatory in the population examined. It was also demonstrated that the serum antibody titers against Pg fimbriae could be useful for screening individuals with moderate to severe periodontitis.

Chlamydial serologic characteristics among intrauterine contraceptive device users: Does copper inhibit chlamydial infection in the female genital tract?

Our objective was to assess the association between copper intrauterine contraceptive device use and the level of antichlamydial antibodies. Fifty-four women (29 with history of ectopic pregnancy, 2 with non-tubal factor infertility, 1 with tubal factor infertility, and 22 with intact intrauterine pregnancies) with current or prior intrauterine contraceptive device use were compared with 60 prenatal control subjects with respect to antichlamydial antibodies. When the intrauterine contraceptive device user group was subdivided into copper users and Lippes Loop device users, a significantly lower geometric mean serum antibody titer among copper intrauterine contraceptive device users was detected. The odds ratio estimates for past chlamydial exposure (> or = 1:64 immunoglobulin G, > or = 1:128 immunoglobulin G) in users of noncopper versus copper intrauterine contraceptive devices were 9.1 (95% confidence interval 1.9 to 43.0) and 10.5 (95% confidence interval 1.5 to 71.8), respectively. The lower geometric mean serum antibody titer of antichlamydial antibody among copper versus Lippes Loop device users and the large association measured between past chlamydial infection and noncopper intrauterine contraceptive device use suggest that copper may have a protective effect against Chlamydia trachomatis infection or a suppressive effect on development of antichlamydial antibodies.

Serotype-Specific Serum IgG Antibodies to Lipopolysaccharides of Pseudomonas aeruginosa in Cystic Fibrosis: Correlation to Disease, Subclass Distribution, and Experimental Protective Capacity

Various studies have demonstrated pronounced systemic IgG response to Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF). However, antibody response to serotype-specific lipopolysaccharides (LPS) has never been studied. ELISA for detection of IgG antibodies to LPS of nine PA-serotypes and to toxin A were performed with serum of 78 CF patients. Anti-LPS profiles of antibodies were confirmed by SDS-PAGE and immunoblotting techniques. The most frequent PA-serotypes found were immunotypes (IT) IT-1 and IT-2, and Habs-3 and Habs-4. Ten patients without PA colonization showed no detectable antibody titers. In patients with chronic PA colonization (n = 46), these antibody titers were significantly (p less than 0.005) higher than in patients with intermittent PA colonization (n = 22). Mean serum antibody titers to LPS of PA IT-1, IT-2, Habs-3, and Habs-4 correlated with duration of PA colonization and with disease severity. Subclass analysis of anti-LPS antibodies revealed elevated levels for all four IgG subclasses and for IgA1. The IgG antibodies to LPS of PA proved to be protective in a murine burn wound sepsis model. We conclude that anti-LPS antibodies to specific PA serotypes in serum may be a sensitive measure of severity and prognosis of CF. Patients with CF show adequate functional immune response to LPS of PA, and it is possible that vaccination against PA before colonization could induce protective immunity.

Acyclovir treatment of varicella in otherwise healthy children

To determine whether acyclovir administered orally affects the duration and severity of varicella in otherwise normal children. Randomized, placebo-controlled, double-blind trial. Patients' residence and university hospital clinic. One hundred five children between 5 and 16 years of age with laboratory-confirmed varicella entered the study. Of the 102 who were included in the final analysis, 50 received acyclovir and 52 received placebo. Placebo or acyclovir was given orally four times daily, for 5 to 7 days. The acyclovir dose was adjusted as follows: 5 to 7 years of age, 20 mg/kg; 7 to 12 years, 15 mg/kg; and 12 to 16 years, 10 mg/kg. Acyclovir recipients, compared with the placebo group, defervesced sooner (median, 1 day vs 2 days; p = 0.001), experienced onset of cutaneous healing sooner, as reflected by a decrease in number of lesions (median, 3 days vs 2 days; p = 0.002), and had fewer skin lesions (median, 500 vs 336; p = 0.02). Acyclovir did not significantly change the rate of complications of varicella (10% in the acyclovir group vs 13.5% among placebo subjects). Adverse drug effects were not observed. Acyclovir recipients had lower geometric mean serum antibody titers to varicella-zoster virus than their placebo counterparts 4 weeks after the onset of illness, but antibody titers in both groups were similar 1 year later. These results provide evidence that acyclovir is useful and well tolerated for treatment of varicella in otherwise healthy children.

POSSIBLE ASSOCIATION OF MYCOPLASMA AND VIRAL RESPIRATORY INFECTIONS WITH BACTERIAL MENINGITIS

The presence of viral infection was evaluated in 160 children older than three months with bacterial meningitis who were admitted to Children's Medical Center or Parkland Memorial Hospital, Dallas, TX, between October 1979 and March 1982. Results were compared with a single serologic specimen in 138 children without meningitis. A recent history of upper respiratory infection was obtained from 60% of patients, including 10/13 with pneumococcal, 9/16 with meningococcal, and 77/131 with Haemophilus influenzae meningitis. Viral infection was documented by serologic response (23.8%) or viral isolation (13.2%) in 63/160 (40%) of patients with meningitis. There were 23 positive cultures (one patient with both adenovirus and respiratory syncytial virus). Picornaviruses, including two rhinoviruses, were isolated from six of the 24 subjects without meningitis who had viral cultures. There were 69 serologic conversions in meningitis patients, with 12 patients converting to two organisms and four patients converting to three organisms. Viral diagnoses included: adenovirus, 32 children; respiratory syncytial virus, 14; influenza A, 8; influenza B, 4; parainfluenza (1, 2, and 3), 12; picornaviruses, 9; herpes simplex virus, 1; and cytomegalovirus, 1. Additionally, 6/15 seroconverted to Mycoplasma pneumoniae. The acute geometric mean serum antibody titers of meningitis patients were lower than those of the comparison group for adenovirus (3.5 vs. 6.6, p less than or equal to 0.001) and influenza B (1.2 vs. 1.6, p less than or equal to 0.05). Twenty nine of 131 patients with H. influenzae had evidence of recent adenovirus infection. Primary infection with adenoviruses and possibly influenza B or mycoplasma precedes development of bacterial meningitis in some patients and may be a predisposing factor.

An immunologic and cultural study of Pityrosporum folliculitis

In patients with Pityrosporum folliculitis the mean serum antibody titer against Pityrosporum orbiculare was significantly higher than in healthy control subjects (p less than 0.01). The mean number of P. orbiculare organisms per square centimeter cultured from normal-looking skin in patients was not significantly higher than the number cultured from normal-looking skin in control subjects. Results of prick tests against P. orbiculare extract were negative or weak, indicating that patients with Pityrosporum folliculitis had no type I hypersensitivity against P. orbiculare. Immunohistochemical staining of skin lesions showed perivascular dermal cell infiltrates near the hair follicles dominated by anti-Leu 3a-reactive T lymphocytes. Human lymphocyte antigens with the DR locus, but not those with the DQ locus, on keratinocytes were observed in one case.

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.

Viral Antibodies in Serum and CSF of Parkinsonian Patients and Controls

• Viral antibody titers to 12 strains of influenza A virus and to 11 other viruses were determined by complement-fixation (CF), hemagglutination-inhibition (HI), and/or indirect hemagglutination (IHA) tests in the serum and cerebrospinal fluid of patients with classical postencephalitic Parkinson's disease (PEPD), idiopathic Parkinson's disease (PD), and nonparkinsonian neurological and medical diseases (controls). We found significant differences of mean serum antibody titers to several viruses in the group with PEPD and the controls. Herpes simplex virus type 1 (CF, IHA), cytomegalovirus (CF, IHA), and herpes simplex virus type 2 (IHA) mean titers were significantly lower in sera of patients with PEPD than in the sera of control patients. Herpes simplex virus 1 (IHA), measles (HI), and rubella (HI) mean titers were significantly lower in sera of patients with PD than in those of controls. Serum influenza mean titers (Hsw1N1) were significantly higher in the patients with PEPD than in the controls; but, this latter finding could not be confirmed when two additional control groups were concurrently tested. We question the biological importance of these viral agents in the etiology of Parkinson's disease and suggest that none of these viruses are causally associated with the disease.

Protective Effect of Active Immunization with Purified Escherichia coli Heat-Labile Enterotoxin in Rats

The protective effect of active immunization by different routes with a purified preparation of the polymyxin-release form of Escherichia coli heat-labile toxin was evaluated in rats. Immunized animals were challenged by placing toxin into ligated ileal loops at dosages which produced either 50% or the maximum secretory response in unimmunized rats. Immunization exclusively by the parenteral route yielded significant protection. Rats were also protected when parenteral priming was followed by boosting given either directly into the duodenum or perorally 2 h after intragastric cimetidine, but not when the peroral boosts were given with bicarbonate. Immunization administered entirely by the peroral route with cimetidine yielded protection but only when the immunizing dosage was fivefold greater than that found effective in the parenteral-peroral approach. Rats immunized exclusively by the parenteral route and those boosted perorally with cimetidine were also tested, and found to be protected, against challenge with viable organisms of strains that produce either heat-labile toxin alone or both heat-labile and heat-stable toxin, but they were not protected against a strain which produces just heat-stable toxin. Geometric mean serum antibody titers were increased by 16-fold or more over control values in those groups of rats in which protection was achieved, with the exception of those immunized exclusively by the peroral route. These observations demonstrate that (i) active immunization with purified E. coli heat-labile toxin results in significant protection against both this toxin as well as viable organisms which produce it, but not against viable strains which produce heat-stable toxin only, and (ii) concomitant ablation of gastric secretion by the use of cimetidine renders the peroral route of immunization effective. They suggest that prophylactic immunization against diarrheal disease caused by heat-labile toxin-producing strains of E. coli may be feasible in humans.

Medical News

<h3>Rubella, juvenile rheumatoid arthritis appear linked—but how?</h3> Evidence of persistent rubella virus infection has been discovered in a group of children with juvenile rheumatoid arthritis, investigators in Buffalo, NY, report. They found that individual and geometric mean serum antibody titers to rubella virus in 31 children with established juvenile rheumatoid arthritis were four to six times higher than those in 32 normal children with a previous history of natural rubella infection. The arthritic children had not been vaccinated for rubella. In addition, the investigators have so far demonstrated the presence of rubella virus antigen in smears of synovial fluid from six out of 32 children with rheumatoid arthritis. The children's synovial fluids were examined by the indirect immunofluorescence technique. The same method has failedto show the presence of rubella virus antigen in synovial fluid from adults with rheumatoid arthritis and one child with septic arthritis. The rubella virus in the