Use of Rabies Virus Vaccine As a Neoantigen to Evaluate Humoral Immune Function in Patients with Primary Immunodeficiency Disorders Receiving Immunoglobulin Replacement Therapy

Rationale: Rabies virus vaccine has been proposed for evaluation of specific antibody response in patients with primary immunodeficiency disorders(PIDs), especially in the setting of intravenous immunoglobulin(IVIG) replacement therapy. More data are needed to define the appropriate protocol and safety of the test.

Methods: We investigated specific antibody response to rabies immunization in 11 patients with predominate antibody deficiency and combined immunodeficiency disorders, compared to 9 healthy controls. All participants received Purified Vero Cell Vaccine 0.5 ml intramuscular regimen on day 0, 3, 7 and 14. Rabies neutralizing antibody(RNab) titers were measured at day 0, 14 and 28 after vaccination.

Results:  The geometric mean titers of RNab in PIDs patients were significantly lower than healthy controls at day 14 (1.19 IU/mL (range 0–6.16)  vs  4.75 IU/mL (range 2.18-19.15) ; p = 0.03) and day 28 (2.09 IU/mL(range 0–10)  vs 10 IU/mL(range 2.19–24.84) ; p= 0.03). Most patients had RNab titers above 0.5 IU/mL(acceptable protective level) by day 14 after vaccination, except patients  with X-linked agammaglobulinemia. There was no adverse event associated with vaccine administration.

Conclusions: We propose the protocol using rabies vaccine as a neoantigen to evaluate humoral immune function in PIDs patients receiving IVIG. The protocol used in our study is safe and elicits antibody response that can discriminate between healthy subjects and those with PIDs on day 14 and more obviously on day 28.