Seroprevalence of tetanus toxoid antibody and booster vaccination efficacy in Japanese travelers

Characterization of neutralizing chimeric heavy-chain antibodies against tetanus toxin

Tetanus toxin (TeNT) is one of the most toxic proteins. Neutralizing antibodies against TeNT are effective in prevention and treatment. In this study, 14 anti-tetanus nanobodies were obtained from a phage display nanobody library by immunizing a camel with the C-terminal receptor-binding domain of TeNT (TeNT-Hc) as the antigen. After fusion with the human Fc fragment, 11 chimeric heavy-chain antibodies demonstrated nanomolar binding toward TeNT-Hc. The results of toxin neutralization experiments showed that T83-7, T83-8, and T83-13 completely protected mice against 20 × the median lethal dose (LD50) at a low concentration. The neutralizing potency of T83-7, T83-8, and T83-13 against TeNT is 0.4 IU/mg, 0.4 IU/mg and 0.2 IU/mg, respectively. In the prophylactic setting, we found that 5 mg/kg of T83-13 provided the mice with full protection from tetanus, even when they were injected 14 days before exposure to 20 × LD50 TeNT. T83-7 and T83-8 were less effective, being fully protective only when challenged 7 or 10 days before exposure, respectively. In the therapeutic setting, 12 h after exposure to TeNT, 1 ~ 5 mg/kg of T83-7, and T83-8 could provide complete protection for mice against 5 × LD50 TeNT, while 1 mg/kg T83-13 could provide complete protection 24 h after exposure to 5 × LD50 TeNT. Our results suggested that these antibodies represent prophylactic and therapeutic activities against TeNT in a mouse model. The T83-7, T83-8, and T83-13 could form the basis for the subsequent development of drugs to treat TeNT toxicity.

Structural basis of tetanus toxin neutralization by native human monoclonal antibodies

Four potent native human monoclonal antibodies (mAbs) targeting distinct epitopes on tetanus toxin (TeNT) are isolated with neutralization potency ranging from approximately 17 mg to 6 mg each that are equivalent to 250 IU of human anti-TeNT immunoglobulin. TT0170 binds fragment B, and TT0069 and TT0155 bind fragment AB. mAb TT0067 binds fragment C and blocks the binding of TeNT to gangliosides. The co-crystal structure of TT0067 with fragment C of TeNT at a 2.0-Å resolution demonstrates that mAb TT0067 directly occupies the W pocket of one of the receptor binding sites on TeNT, resulting in blocking the binding of TeNT to ganglioside on the surface of host cells. This study reveals at the atomic level the mechanism of action by the TeNT neutralizing antibody. The key neutralization epitope on the fragment C of TeNT identified in our work provides the critical information for the development of fragment C of TeNT as a better and safer tetanus vaccine.

Tetanus in the Elderly: The Management of Intensive Care and Prolonged Hospitalization

Tetanus is a potentially fatal infection. Approximately 100 cases are reported in Japan each year; however, little is known about its clinical course and outcomes in the current era of treatment. We herein report three cases of tetanus in elderly patients who survived after mechanical ventilation and intensive care. These patients, together with six other similar cases, had a median weaning period of 31 days and median length of stay of 77 days. In elderly patients, severe systemic forms of tetanus require prolonged mechanical ventilation and hospitalization. To improve prevention, tetanus vaccination should be promoted more aggressively among those who are susceptible to the disease.

Determination of Tetanus Antibody Levels in Trauma Patients Referred To Shahid Beheshti Hospital in Kashan, Iran, 2014

BACKGROUND

There is a noticeable difference in serologic immune status against tetanus among different age and social groups in various countries due to different national vaccination policies and methods.

OBJECTIVES

Considering that the immunization status of trauma patients against tetanus is not-known or uncertain and they may need to receive the vaccine and tetabulin, this study was conducted to determine the tetanus antibody levels in patients referred to the trauma emergency ward of Shahid Beheshti Hospital in Kashan City, Iran.

PATIENTS AND METHODS

This cross-sectional study was performed on 204 trauma patients referred to the trauma emergency ward of Shahid Beheshti hospital in Kashan City, Iran, in 2014. After obtaining a written informed consent from the patients, a questionnaire consisted of demographic information and tetanus vaccination record was completed by the patients. Afterwards, a 4 - 5 mL venous blood sample was taken from each patient and the tetanus antibody level (IgG) was measured using the enzyme-linked immunosorbent assay method. The tetanus antibody levels equal or more than 0.1 IU/mL were considered protective. Data were analyzed using chi-square test, independent t-test and one-way ANOVA with SPSS software version 16.

RESULTS

From a total of 204 patients, 35 cases (16.7%) were females and 169 (83.2%) were males with the mean age of 40.9 ± 3.7 years. There was no statistically significant difference in the tetanus antibody levels between both sexes (P = 0.09). Moreover, there was no significant difference in immunization status between the patients who had a history of tetanus vaccination and those who had not received the vaccine before (P = 0.67). The antibody levels were significantly reduced with the passage of time since the last vaccination (P < 0.001). Also, 87.3% of the patients had the high protective level of immunity to tetanus.

CONCLUSIONS

The findings of the present study show a high level of tetanus antibody among trauma patients in this hospital; so, taking the tetanus vaccine history can be misleading. It is suggested that further studies be performed in different regions of our country and with larger sample sizes and detection of the immunization status of patients by measuring anti-tetanus antibody levels among trauma patients is recommended to make suitable policy for a national vaccine protocol in the future.