PURPOSE: A strengthened mutant strain of influenza virus is provided to remarkably reduce body weight and to show high fatality in an infected mouse, thereby evaluating the efficacy of a vaccine. CONSTITUTION: A strengthened mutant strain of influenza virus contains haemagglutinin of sequence number 2 or neuraminidase of sequence number 4. A kit for determining the efficacy of a vaccine contains the strengthened mutant strain. 144th amino acid (aspartic acid, D) is substituted with glutaric acid (D) in virus of A(H1N1)pdA/Korea/01/2009.본 발명은 강독화된 인플루엔자 바이러스의 변이주에 관한 것으로, 본 발명에 따른 강독화된 바이러스는, 감염에 의한 마우스의 현격한 체중 감소 또는 높은 치사율을 나타내므로 백신의 효능평가를 하는 데에 사용될 수 있다.
