Protection of mice against experimental Japanese encephalitis virus infections by neutralizing anti-glycoprotein E monoclonal antibodies

Neutralizing monoclonal antibodies (MAbs) to glycoprotein E (gpE) of Japanese encephalitis (JE) virus given intraperitoneally (i.p.) (0.1 ml of immune ascitic fluid (AF) diluted 1:10 per mouse) to about 4-week-old Swiss mice 1 day prior or 2 days after the virus challenge (100 LD50 of JE virus administered intracerebrally (i.c.)) resulted in a decreased mortality along with an increased survival of the animals as demonstrated by the HAI-positive virus-specific (Hs) MAbs. The protective effect produced by four Hs MAbs was maximum when given 1 day prior the virus challenge, while other, namely HAI-positive flavivirus cross-reactive (Hx) and HAI-negative virus-specific (NHs) MAbs did not produce any effect. Interestingly, one of the two NHs MAbs, namely NHs-1 showed a reduced survival of mice given the MAb 2 days after the virus challenge. Administration of combinations of two or more Hs MAbs may be recommended due to their possible enhanced protection against JE virus infections in mice.