Influenza B viruses in pigs, Taiwan.

Background: Influenza B viruses (IBVs) have never been isolated from natural-infected pigs in clinical cases, although the susceptibility of domestic pigs to experimental IBV infections had been confirmed as well as IBV-specific antibodies were detected from pigs under natural and experimental conditions.

Objectives: We aimed to assess and investigate the activities for infection and circulation of IBVs in pigs.

Methods: Annual active surveys for influenza have been implemented on swine populations in Taiwan since July 1998.

Baculovirus vector as an avian influenza vaccine: hemagglutinin expression and presentation augment the vaccine immunogenicity.

Baculovirus simultaneously displaying and expressing the avian influenza virus (AIV) hemagglutinin (HA) protein can induce potent anti-HA humoral and cellular immune responses. Based on the hypothesis that improving the antigen expression and presentation can further boost the AIV vaccine efficacies, we first constructed a baculoviral vector (Bac-HAW) with HA gene fused with the woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) near its 3' end and expressed under the control of the hybrid CAG promoter. The WPRE fusion improved the HA expression and augmented the humoral and Th1 cellular immune responses after intramuscular administration into BALB/c mice.

Baculovirus as an avian influenza vaccine vector: differential immune responses elicited by different vector forms.

Baculovirus is an enveloped virus that infects insects in nature and has emerged as a novel vaccine vector. We previously constructed a recombinant baculovirus displaying the hemagglutinin protein (HA) of avian influenza virus (AIV) on the viral envelope (Bac-HA64), and demonstrated the induction of humoral responses in immunized mice. To improve the vector design and explore how the vector forms influence the vaccine efficacy, we constructed two more baculoviruses Bac-CHA and Bac-CHA/HA64.