Respiratory disease and increased mortality occurred in minks on two farms in the Netherlands, with interstitial pneumonia and SARS-CoV-2 RNA in organ and swab samples. On both farms, at least one worker had coronavirus disease-associated symptoms before the outbreak. Variations in mink-derived viral genomes showed between-mink transmission and no infection link between the farms. Inhalable dust contained viral RNA, indicating possible exposure of workers. One worker is assumed to have attracted the virus from mink.

In April 2020, respiratory disease and increased mortality were observed in farmed mink on two farms in the Netherlands. In both farms, at least one worker had been found positive for SARS-CoV-2. Necropsies of the mink revealed interstitial pneumonia, and organ and swab samples tested positive for SARS-CoV-2 RNA by qPCR. Variations in viral genomes point at between-mink transmission on the farms and lack of infection link between the farms. Inhalable dust in the mink houses contained viral RNA, indicating possible exposure of workers.

Infectious bursal disease virus (IBDV) is a double-stranded RNA (dsRNA) virus of the Birnaviridae family. Its two genome segments are encapsidated together with multiple copies of the viral RNA-dependent RNA polymerase, VP1, in a single-shell capsid that is composed of VP2 and VP3. In this study we identified the domains responsible for the interaction between VP3 and VP1. Using the yeast two-hybrid system we found that VP1 binds to VP3 through an internal domain, while VP3 interacts with VP1 solely by its carboxy-terminal 10 amino acids. These results were confirmed by using a reverse-genetics system that allowed us to analyze the interaction of carboxy-terminally truncated VP3 molecules with VP1 in infected cells. Coimmunoprecipitations with VP1-and VP3-specific antibodies revealed that the interaction is extremely sensitive to truncation of VP3. The mere deletion of the C-terminal residue reduced coprecipitation almost completely and also fully abolished production of infectious virions. Surprisingly, these experiments additionally revealed that VP3 also binds to RNA. RNase treatments and reverse transcription-PCR analyses of the immunoprecipitates demonstrated that VP3 interacts with dsRNA of both viral genome segments. This interaction is not mediated by the carboxyterminal domain of VP3 since C-terminal truncations of 1, 5, or 10 residues did not prevent formation of the VP3-dsRNA complexes. VP3 seems to be the key organizer of birnavirus structure, as it maintains critical interactions with all components of the viral particle: itself, VP2, VP1, and the two genomic dsRNAs.Infectious bursal disease virus (IBDV) is the causative agent of a highly contagious disease of young chickens. IBDV multiplies rapidly in developing B lymphocytes in the bursa of Fabricius, leading to immunosuppression and increased susceptibility to other diseases. Of the two IBDV serotypes, only serotype 1 is pathogenic to chickens (23). IBDV belongs to the family Birnaviridae (17). Members of this family are characterized by a double-stranded RNA (dsRNA) genome consisting of two segments (A and B) that are packaged within a singleshell icosahedral capsid of 60 nm.The smaller genome segment, B, of IBDV (approximately 2.9 kb) encodes a single protein, viral protein 1 (VP1; 91 kDa). This protein is the putative RNA-dependent RNA polymerase (12). It has the intriguing feature of occurring in virions in two forms: a form in which it is covalently bound to the 5Ј ends of the genomic dsRNA segments (viral protein genome-linked [VPg]) (16) and a free-polypeptide form. The larger dsRNA segment, A (approximately 3.3 kb), contains two partly overlapping open reading frames (ORFs). The first ORF encodes nonstructural protein VP5 (17 kDa). This protein proved to be nonessential for viral replication and infection (33, 41). The second ORF encodes a 110-kDa polyprotein, which is autocatalytically cleaved to give pVP2 (48 kDa), VP4 (28 kDa), and VP3 (32 kDa). The viral protease VP4, through a catalytic site belonging to the Lon protease family, is r...

Little is known about the intermolecular interactions between the viral proteins of infectious bursal disease virus (IBDV

Inoculation of influenza (H5N1) into beagles resulted in virus excretion and rapid seroconversion with no disease. Binding studies that used labeled influenza (H5N1) showed virus attachment to higher and lower respiratory tract tissues. Thus, dogs that are subclinically infected with influenza (H5N1) may contribute to virus spread.