Prophylaxis and therapy for Chikungunya virus infection

Abstract

Background: Chikungunya virus (CHIKV) is a recently reemerged arbovirus responsible for a massive outbreak of infection in the Indian Ocean region and India that has a very significant potential to spread globally because of the worldwide distribution of its mosquito vectors. CHIKV induces a usually self-limited disease in humans that is characterized by fever, arthralgia, myalgia, and rash; however, cases of severe CHIKV infection have recently been described, particularly in adults with underlying condition and neonates born to viremic mothers.

Methods: Human polyvalent immunoglobulins were purified from plasma samples obtained from donors in the convalescent phase of CHIKV infection, and the preventive and curative effects of these immunoglobulins were investigated in 2 mouse models of CHIKV infection that we developed.

Results: CHIKV immunoglobulins contain anti-CHIKV antibodies and exhibit a high in vitro neutralizing activity and a powerful prophylactic and therapeutic efficacy against CHIKV infection in vivo, including in the neonate.

Conclusions: Administration of CHIKV immunoglobulins may constitute a safe and efficacious prevention strategy and treatment for individuals exposed to CHIKV who are at risk of severe infection, such as neonates born to viremic mothers and adults with underlying conditions. These results provide a proof-of-concept for purifying human immunoglobulins from plasma samples from patients in the convalescent phase of an emerging infectious disease for which neither prevention nor treatment is available.

Figure 1

Immunoreactivity against Chikungunya virus (CHIKV) of human plasma samples obtained from donors in the convalescent phase of CHIKV infection. The titer of CHIKV neutralizing antibodies was determined by a standard neutralization assay, and the neutralizing titers are expressed as the inverse of the last dilution for which at least 80% of CHIKV plaque reduction was obtained (PRNT₈₀). A Neutralizing titers of 71 plasma samples positive for CHIKV by enzyme-linked immunosorbent assay (ELISA). The number above each bar corresponds to the percentage of samples positive for CHIKV at the indicated titer. B Neutralizing titers and ELISA titers in 27 plasma samples randomly chosen among the 71 plasma samples positive for CHIKV by ELISA. Titers in ELISA are expressed as the inverse of the last dilution of plasma for which a positive ratio of optical density has been obtained

Table 1

Immunoreactivity against Chikungunya Virus (CHIKV) of Human Plasma Obtained from Donors in the Convalescent Phase of CHIKV Infection and of CHIKV Immunoglobulin (CHIKVIg)

Figure 2

Chikungunya virus (CHIKV) infection prophylaxis with human plasma and purified immunoglobulin (Ig) in interferon (IFN)–α/βR^−/− adult mice. A Passive administration of nonimmune and immune human plasma or human normal Ig and human CHIKVIg to IFN-α/βR^−/− adult mice infected by intradermal route with 10 plaque-forming units (PFU) of CHIKV. Plasma samples, normal Ig, and CHIKVIg were administrated as a single dose via intraperitoneal route immediately after CHIKV injection. Data correspond to at least 7 mice per condition. Statistical differences in the comparison with the phosphate-buffered saline (PBS) controls were as follows: human plasma A and normal Ig, P>.9; human plasma B, human plasma C, and CHIKVIg, P<.001. B Passive administration of CHIKVIg to IFN-α/βR^−/− adult mice infected by intradermal route with 10–10⁶ PFU of CHIKV. Antibodies were administrated as a single dose via intraperitoneal route immediately after CHIKV injection. Data correspond to 7 mice per condition in mean. Statistical differences were not significant, at P>.9. C Passive administration with different amounts of CHIKVIg to IFN- α/βR^−/− adult mice infected by intradermal route with 10 PFU of CHIKV. Nondiluted CHIKVIg (25 mg; 830 mg/kg) or diluted CHIKVIg (from 1:2 [12.5 mg; 415 mg/kg] to 1:128 [0.195 mg; 6.5 mg/kg]) were administered as a single dose via intraperitoneal route immediately after CHIKV injection. Data correspond to at least 10 mice per condition. Statistical differences in the comparison with PBS controls were as follows: CHIKVIg (25 mg) and CHIKVIg 1:2–1:32, P<.001; CHIKVIg 1:64 and 1:128, P>.9. D Viral titers in tissue and serum samples from mice inoculated with 10⁶ PFU of CHIKV via the intradermal route and injected with PBS, normal IgG, or CHIKVIg. Mice were sacrificed at the indicated times, and the amount of infectious virus in serum and tissue samples was quantified by tissue cytopathic infectious dose 50 (TCID50). Each data point represents the arithmetic mean±standard deviation for at least 4 mice. A broken line indicates the detection threshold

Figure 3

Chikungunya virus (CHIKV) infection prophylaxis with human plasma and purified immunoglobulin (Ig) in B6 mouse neonates. A Passive administration of nonimmune and immune human plasma and normal Ig or CHIKV immunoglobulin (CHIKVIg) to 8–9-day-old mice infected by intradermal route with 10⁶ plaque-forming units (PFU) of CHIKV. The indicated plasma and Ig were administrated as a single dose via intraperitoneal route immediately after CHIKV injection. Data reflect at least 12 mice per condition. Statistical differences in the comparison with phosphate-buffered saline (PBS) controls were as follows: human plasma A and normal Ig, P>.9; human plasma B and CHIKVIg, P<.001. B Passive administration with different amounts of CHIKVIg to 8–9-day-old mice infected by intradermal route with 10⁶ PFU of CHIKV. Nondiluted (10 mg) or diluted (1:2–1:128) CHIKVIg was administrated as a single dose via intraperitoneal route immediately after CHIKV injection. Data correspond to at least 12 mice per condition. P<.001 for statistical differences in the comparison of PBS controls with mice treated with CHIKVIg (10 mg) and CHIKVIg 1:2–1:128. C Viral titers in tissue and serum samples from mice inoculated with 10⁶ PFU of CHIKV via the intradermal route and injected with PBS, normal Ig, or CHIKVIg. Mice were sacrificed at the indicated times, and the amount of infectious virus in serum and tissue samples was quantified by tissue cytopathic infectious dose 50 (TCID50). Each data point represents the arithmetic mean±standard deviation for at least 4 mice. A broken line indicates the detection threshold

Figure 4

Therapeutic activity of Chikungunya virus (CHIKV) immunoglobulin (Ig) in IFN-α/βR^−/− adult mice and B6 mouse neonates. A A single dose (25 mg) of CHIKVIg was administrated via intraperitoneal route immediately after CHIKV injection (0 h) or at the indicated hours after intradermal administration of 10 plaque-forming units (PFU) of CHIKV in IFN-α/βR^−/− adult mice. Data correspond to at least 7 mice per condition. P<.001 for statistical differences in the comparison with phosphate-buffered saline (PBS) controls. B A single dose (10 mg) of CHIKVIg was administrated via intraperitoneal route immediately after CHIKV injection (0 h) or at the indicated hours after intradermal administration of 10⁶ PFU of CHIKV in B6 mouse neonates. Data correspond to 12 mice per condition in mean. Statistical differences in the comparison with PBS controls were as follows: CHIKVIg 0 h and 8 h after infection, P<.001; CHIKVIg 24 h and 48 h after infection, P<.005