In several parts of China, there have been a large number of hydropericardium syndrome (HPS) outbreaks caused by serotype 4 fowl adenovirus (FAdV­4) in broiler chickens since 2015. These outbreak-associated FAdV-4 strains were distinct from previous circulating strains which did not lead to severe HPS outbreaks. To better understand the molecular epidemiology of the currently circulating FAdV strains for effective diagnosis and treatment of HPS, we isolated 12 HPS outbreak-associated FAdV-4 strains from different regions in central China and investigated their molecular characteristics by performing phylogenetic analyses based on the hexon genes. Our results indicated the FAdV-4 strains in this study all belonged to serotype FAdV-4, species FAdV-C. And in comparison with ON1, KR5, MX-SHP95, PK-01, PJ-06 strains within the cluster where outbreak-associated FAdV-4 strains were located, the nucleotide sequence divergence were 1.31, 1.10, 1.42, 2.77 and 2.84%, respectively. Phylogenetic analyses revealed the hexon genes of the 12 outbreak-associated strains clustered to a relatively independent branch of the tree, and evolved from the same ancestor and we suggested that these outbreak-associated FAdV-4 strains originate from earlier strains in India.

In several parts of China, there have been a large number of pseudorabies (PR) outbreaks which have devastated many swine farms even though the herds had been previously immunized with gE-deleted vaccines (Bartha-K61). The emergence of these outbreak-associated PRV strains might indicate that Bartha-K61 vaccine could not provide effective protection and poses challenges for current serologic diagnostics of anti-PRV antibodies. Here, we performed phylogenetic analyses based on partial gE, gB, and gC genes to provide information about the molecular epidemiology, diagnostics, and immune protection in these outbreak-associated PRV strains. Our results indicated that the maximal nucleotide sequence divergence for gE, gB, and gC genes are 1.7, 0.4, and 2.7 % within the cluster where outbreak-associated PRV strains were located, and are 2.3, 2.7, and 7.6 % with other clusters in the phylogenetic trees, respectively. Phylogenetic analyses revealed that gE, gB, and gC genes of the twelve outbreak-associated PRV strains clustered to a relatively independent branch of the tree, and evolved from the same ancestor with strains Ea-China-1999, Fa-China-2001, and BJ-China-2008. The genetic relationship between these outbreak-associated PRV strains and strain Bartha is not close which may genetically explain the emergence of PR outbreaks in Bartha-K61-vaccinated swine farms. We suggest that these outbreak-associated PRV strains originate from earlier strains in local regions in China.

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Abstract.A rapid (<5 min) immunochromatographic strip using a colloidal gold-labeled antigen probe was successfully developed and applied for the detection of Porcine circovirus-2 (PCV-2) antibodies in swine. Recombinant Cap protein truncated nuclear localization signal of PCV-2, was expressed and labeled with colloidal gold. This conjugate was dispensed on a conjugate pad as the detector. Staphylococcal protein A and purified porcine anti-PCV-2 antibodies were blotted on a nitrocellulose membrane for the test and control lines, respectively. Sensitivity and specificity of this strip test was evaluated using PCV-2 antisera as well as other sera from pigs infected with a variety of swine viruses. For the validation of this strip test, 500 clinical swine serum samples were assessed both by the strip and a commercial enzyme-linked immunosorbent assay (ELISA) kit. The agreement between the immunochromatographic strip and ELISA kit was 94.00%. This strip possesses high sensitivity and specificity and may be useful as a candidate for rapid diagnosis of PCV-2 antibodies in the field.

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