Swine influenza A viruses (swIAVs) with a truncated NS1del126 protein were strongly attenuated in previous laboratory-based safety studies and therefore approved for use as LAIVs for swine in the United States. In the field, however, the LAIV strains were detected in diagnostic samples and could regain a wild-type NS1 via reassortment with endemic swIAVs.

Surveillance of swine influenza A viruses (swIAV) allows timely detection and identification of new variants with potential zoonotic risks. In this study, we aimed to identify swIAV subtypes that circulated in pigs in Belgium and the Netherlands between 2014 and 2019, and characterize their genetic and antigenic evolution. We subtyped all isolates and analyzed hemagglutinin sequences and hemagglutination inhibition assay data for H1 swIAV, which were the dominant HA subtype. We also analyzed whole genome sequences (WGS) of selected isolates. Out of 200 samples, 89 tested positive for swIAV. swIAV of H1N1, H1N2 and H3N2 subtypes were detected. Analysis of WGS of 18 H1 swIAV isolates revealed three newly emerged genotypes. The European avian-like H1 swIAV (lineage 1C) were predominant and accounted for 47.2% of the total isolates. They were shown to evolve faster than the European human-like H1 (1B lineage) swIAV, which represented 27% of the isolates. The 2009 pandemic H1 swIAV (lineage 1A) accounted for only 5.6% of the isolates and showed divergence from their precursor virus. These results point to the increasing divergence of swIAV and stress the need for continuous surveillance of swIAV.

In a previous study in influenza-naïve pigs, heterologous prime-boost vaccination with monovalent, adjuvanted whole inactivated vaccines (WIV) based on the European swine influenza A virus (SwIAV) strain, A/swine/Gent/172/2008 (G08), followed by the US SwIAV strain, A/swine/Pennsylvania/A01076777/2010 (PA10), was shown to induce broadly cross-reactive hemagglutination inhibition (HI) antibodies against 12 out of 15 antigenically distinct H3N2 influenza strains. Here, we used the pig model to examine the efficacy of that particular heterologous prime-boost vaccination regimen, in individuals with pre-existing infection-immunity. Pigs were first inoculated intranasally with the human H3N2 strain, A/Nanchang/933/1995. Seven weeks later, they were vaccinated intramuscularly with G08 followed by PA10 or vice versa. We examined serum antibody responses against the hemagglutinin and neuraminidase, and antibody-secreting cell (ASC) responses in peripheral blood, draining lymph nodes, and nasal mucosa (NMC), in ELISPOT assays. Vaccination induced up to 10-fold higher HI antibody titers than in naïve pigs, with broader cross-reactivity, and protection against challenge with an antigenically distant H3N2 strain. It also boosted ASC responses in lymph nodes and NMC. Our results show that intramuscular administration of WIV can lead to enhanced antibody responses and cross-reactivity in pre-immune subjects, and recall of ASC responses in lymph nodes and NMC.

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Background: The chewing of khat leaves (Catha edulis Forsk) is widely practiced in East Africa and parts of the Middle East, where it forms a deep-rooted social and cultural function. Consumption of Khat is common among men but recently it has extended to women. Biochemical and toxicological effects of Khat on pregnancy and fetal development in lower animals has been noted. Studies on the effect of khat consumption has focused on men thus no data is available on women and especially during pregnancy. This study was conducted to evaluate the effects of khat on liver and kidney functions during pregnancy using olive baboons as experimental models. Methods: Six pregnant olive baboons were randomly assigned into khat treatment group (n=3) that received 100mls of crude khat at a dose of 5 g/kg body weight/week for 8 weeks and the control group (n=3) received normal saline during the second trimester. Blood pressure, temperature and weight changes were measured weekly. Blood was collected to assay for liver and kidney function tests and liver and kidney tissues collected during necropsy for histopathological examinations. Results: The levels of aminotransferases, urea and creatinine in the khat treated group were significantly elevated compared to those in the control group. There was a decrease of body weight in the dams, fetal birth weight and levels of albumin and sodium in treatment group compared to those in the control group. Kidney and liver tissues of the baboons and their fetuses treated with khat showed necrosis, periportal fibrosis with focal degenerative changes, glomerular degeneration and infiltration with lymphocytes. Blood pressure was not significantly different between the two groups. Conclusion: The findings show that crude khat may damage the liver and kidneys and modulate the levels of liver enzymes, urea, creatinine and electrolytes essential for liver and kidney functions. Khat is not safe and its use during pregnancy should be discouraged.