M.O. Fatokun1, O.O. Enabor1, F.A. Bello1, O.A. Adesina1 and G.O. Arinola2
- Department of Obstetrics and Gynaecology, University College Hospital, Ibadan, Nigeria
- Department of Chemical Pathology, Immunology Unit, College of Medicine, University of Ibadan, Ibadan, Nigeria.
Background: HIV infection affects millions of women and children, particularly in sub-Saharan Africa. Tetanus also causes significant maternal and neonatal morbidity and mortality in developing countries. Since the main effect of HIV is immunosuppression, there is potential for a negative influence on the host immune response to tetanus in women with HIV.
Objective: This case-control study evaluated the effect of HIV infection on maternal tetanus antibody production and neonatal tetanus antibody levels.
Methods: Thirty registered primigravidae were recruited from the clinic;15 were HIV positive and 15 were HIV negative. Serum samples of maternal and cord blood were obtained from both groups at delivery. Maternal total IgG and cord blood tetanus-specific antibody were estimated by Enzyme Linked Immunosorbent Assay.
Results: There was no significant difference in the total IgG level of HIV positive mothers compared with HIV negative mothers. No significant difference in the tetanus-specific IgG level in the cord blood of babies of HIV positive mothers compared with cord blood of babies of the HIV negative mothers.
Conclusion: HIV infection did not significantly reduce total IgG production in Nigerian primigravidae. Tetanus-specific IgG levels were above protective levels in neonates of HIV positive mothers suggesting adequate protection.
Keywords: Tetanus, Antibody, Pregnancy, Immunisation, HIV.
Dr. F.A. Bello
Dept. of Obs. and Gynae,
University College Hospital,
The devastation of Human Immunodeficiency Virus (HIV) infection remains pronounced globally, particularly in sub-Saharan Africa where an estimated 25.8 million people including pregnant women are affected1. In 2010, antenatal client prevalence of HIV in Nigeria was 4.1%2. It was reported that 90% of paediatric HIV cases were due to mother-to-child transmission (MTCT) of HIV3.
Literature reports that the phenomena of inflammation and immunomodulation are involved either in HIV infection4 or during pregnancy5, which can affect vaccine response. Studies have highlighted the involvement of abnormal cellular and humoral immune responses during HIV infection. This includes abnormal pattern of serum protein electrophoresis, polyclonal hypergammaglobulinaemia, hyperproteinemia and plasma cell dyscrasias6,7. In addition, impaired phagocytosis, reduced number and functions of Tlymphocytes were reported during pregnancy8. Despite maternal hypergammaglobulinaemia in pregnant HIV infected mothers, reduced IgG transplacental transference to the foetus has been reported6,9,10, which in turn, may influence vaccine response and neonatal immunity.
For the protection of mothers and babies, pregnant women in developing countries are usually vaccinated against tetanus. While no vaccine has yet been licenced for the prevention of HIV, maternal and neonatal tetanus prophylaxis has actively been pursued by the World Health Organization (WHO) since 198911,12. Newborn babies are protected from neonatal tetanus by maternal anti-tetanus antibody of the IgG class which is transplacentally transferred from third trimester of gestation following tetanus toxoid vaccination in pregnant women.
Immunization for pregnant women with tetanus toxoid vaccine is the single most effective strategy independent of other interventions in eliminating neonatal tetanus11,12. However, there are conflicting reports of the influence of maternal HIV infection on anti-tetanus antibody production by the mothers as well as its transfer through the placenta to their unborn babies. For instance, lower anti-tetanus antibody levels in HIV infected women were reported from Senegal13 and Brazil14, but not in The Gambia15. Cumberland et al.6 found reduced transplacental transfer of tetanus antibody, and about 50% lower antibody levels in cord serum. In contrast, De Moraes-Pinto et al. from Malawi found that maternal HIV infection had no effect on cord anti-tetanus IgG levels as well as transplacental transfer of anti-tetanus antibody10. In addition, seroprevalence studies have suggested that HIV-infected patients are less likely to have adequate anti-tetanus antibodies. The progressive decline of CD4 levels in HIV-infected individuals could potentially lead to lost immunity to tetanus16,17.
With the potential for HIV infection among women in the reproductive age group, and specifically pregnant women, it is necessary to evaluate the effect of HIV infection on the efficacy of tetanus toxoid in this group of people where tetanus toxoid vaccination is recommended. It is hypothesized that passively transferred immunity to the developing foetus by pregnant mothers will be affected by HIV infection. This study assessed tetanus-specific IgG levels of cord blood from babies born to HIV positive and negative primigravidae who received tetanus immunization.