Effect of infections with swine fever virus on immune functions. III. Antibody response to lipopolysaccharide and sheep red blood cells

In order to determine the effect of infections with low-virulent swine fever virus (SFV) on antibody responses, pigs were administered lipopolysaccharide (LPS) or sheep red blood cells (SRBC), 2 days after infection. Infected pigs showed an enhanced primary response to LPS late during infection. The secondary response to LPS seemed to be unaffected. Both the primary and secondary antibody response to SRBC appeared to be enhanced rather than depressed in infected pigs. These in vivo findings suggest that pigs infected with low-virulent SFV do not develop a depression of B lymphocyte function.     

Intranasal vaccination of pigs against Aujeszky's disease: comparison with inactivated vaccines in pigs with low maternal antibody titres

Intranasal vaccination with an attenuated Aujeszky's disease virus strain was compared with parenteral vaccination with two inactivated virus vaccines, in 10-week-old pigs with low levels of maternal antibody. Intranasal vaccination conferred a much better protection than parenteral vaccination with the two inactivated vaccines against challenge two months later, as evidenced by shorter periods of growth arrest and fever and a greater reduction of virulent virus shedding after challenge-exposure.     

Avian infectious bronchitis: cross-protection studies using different Australian subtypes

The cross-immunity of vaccinated chickens after challenge with some Australian infectious bronchitis viruses was assessed by humoral antibody responses and by ciliary activity in tracheal rings of vaccinated chickens following challenge. Four viruses were used for vaccination: Vac 3, Vac 4, both current infectious bronchitis vaccine viruses, and Q1/76 and N2/62. IBV N1/62 (synonym T0 and infectious bronchitis virus N9/74 (synonym Appin) were used to challenge the vaccinated chickens. Results showed a lack of correlation between humoral antibody levels and protection. Cross-immunity was found after vaccination with each subtype, but was lower for Vac 3 and Vac 4 than for Q1/76 and N2/62.