Phylogenetic analysis of ORF5 and ORF7 sequences of porcine reproductive and respiratory syndrome virus (PRRSV) from PRRS-positive Italian farms: a showcase for PRRSV epidemiology and its consequences on farm management.

We investigated the dynamics of porcine reproductive and respiratory syndrome virus (PRRSV) variability in a range of swine PRRS-positive farms located in Northern Italy, to provide insights into the epidemiology and diffusion of the virus, particularly throughout the entire swine production chain. In this context, we also examined the effectiveness and the critical points of a recently developed gilts acclimatization program in swine breeder farms. To achieve these aims, we designed new primers and determined 64 complete open reading frame 5 (ORF5) sequences, representing Italian PRRSV field strains and the European vaccine Porcilis strain (Intervet); in addition, the more conserved ORF7 of 11 PRRSV strains were sequenced. The domains' prediction of their putative protein sequences was performed as well. Based on these sequences, phylogenetic trees were inferred which revealed a high degree of variability among the PRRSV Italian strains. The outcomes of the phylogenetic analysis showed that the most frequent source of infection in PRRS-positive farms (sow herds, nursery sites, fattening units) was the introduction of animals carrying a new variant and not the modification of already present variants; moreover, the integration of data from phylogenetic analysis and from the clinical and serological status of the swine herds suggested that the acclimatization program could be a valid tool to stabilize the PRRS clinical picture in farms, only when applied in combination with rigorous bio-security routine management and avoid the incoming of new PRRSV variants.

Field and laboratory findings of the first incursion of the Asian H5N1 highly pathogenic avian influenza virus in Africa.

In mid-January 2006 an outbreak of avian influenza in domestic birds was recorded in Kaduna State, Nigeria. The virus responsible for the outbreak was characterized as a highly pathogenic avian influenza H5N1 (A/chicken/Nigeria/641/06), belonging to the Qinghai lineage. The index case occurred on a farm containing mixed avian species including free-range birds. Clinical signs and mortality were observed in chickens, geese and ostriches. The present paper describes the clinical, pathological and virological findings of this outbreak.