The health and vigour of honeybee colonies are threatened by numerous parasites (such as Varroa destructor and Nosema spp.) and pathogens, including viruses, bacteria, protozoa. Among honeybee pathogens, viruses are one of the major threats to the health and well-being of honeybees and cause serious concern for researchers and beekeepers. To tone down the threats posed by these invasive organisms, a better understanding of bee viral infections will be of crucial importance in developing effective and environmentally benign disease control strategies. Here we summarize recent progress in the understanding of the morphology, genome organization, transmission, epidemiology and pathogenesis of eight honeybee viruses: Deformed wing virus (DWV) and Kakugo virus (KV); Sacbrood virus (SBV); Black Queen cell virus (BQCV); Acute bee paralysis virus (ABPV); Kashmir bee virus (KBV); Israeli Acute Paralysis Virus (IAPV); Chronic bee paralysis virus (CBPV). The review has been designed to provide researchers in the field with updated information about honeybee viruses and to serve as a starting point for future research.

Norovirus (NoV) RNA was detected in the stools of 6 out 14 (42.8%) 8–12-week-old cats with enteritis from a feline shelter, in New York State. Upon sequence analysis of the complete capsid, the six NoVs were found to be identical, suggesting the spread of a unique NoV strain in the shelter. The full-length genomic sequence (7839 nt) of one feline NoV, CU081210E/2010/US, was determined. In the capsid protein VP1 region, the virus displayed the highest amino acid identity to animal genogroup IV genotype 2 (GIV.2) NoVs: lion/Pistoia-387/06/IT (97.9%) and dog/Bari-170/07/IT (90.4%). These findings document the discovery of a novel feline calicivirus, different from vesiviruses, and extend the spectrum of NoV host range. Epidemiological studies using feline NoV-specific diagnostic tools and experimental infection of cats are required to understand whether NoVs have a pathogenic role in this species.

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An outbreak of abortion affecting multiparous cows was associated with Hobi-like pestivirus infection. Viral RNA and antigens were detected in the tissues of two aborted fetuses. Molecular assays for other common abortogenic agents tested negative. At the genetic level, the Hobi-like pestivirus displayed the closest relatedness to Italian, Australian, and South American viruses, whereas it diverged from the prototype Thai isolate. These findings may have important implications for the pestivirus control/ eradication programs in cattle herds. Bovine viral diarrhea viruses (BVDVs) are members of the genus Pestivirus (family Flaviviridae), responsible for a number of clinical signs, including subclinical infections, immunosuppression, acute diarrhea, respiratory disease, reproductive failures, and mucosal disease in persistently infected calves. Reproductive disorders caused by BVDVs vary according to the fetal age and include embryo death, abortion, mummification, congenital abnormalities, or stillbirths (2). Thus far, two different BVDV species have been recognized, BVDV-1 and BVDV-2, that cocirculate in cattle herds worldwide (20). In 2004, an atypical pestivirus, strain D32/00_Hobi, was isolated from a contaminated batch of fetal calf serum (FCS) (19). The virus was distantly related to BVDV-1/BVDV-2, and it was proposed as a prototype of a new pestivirus species (14, 15). Hobi-like sequences have been repeatedly detected in commercial FCS batches (17,22,23), whereas there are few reports on natural infections (4, 5, 21, 23) and clinical outbreaks (5). The virus has been recently detected in aborted bovine fetuses in Brazil, thus suggesting direct clinical implications (4).Here, we report the isolation and genetic characterization of a Hobi-like strain detected from aborted fetuses in southern Italy. The abortion outbreak occurred in June 2011 in a cattle herd where a Hobi-like pestivirus-associated respiratory disease had been recently described (5). Abortion was observed in eight multiparous cows in a group of 270 lactating Holstein cows and occurred between the fourth and sixth months of pregnancy. The animals neither showed prodromal signs nor presented postabortion complications. Two aborted fetuses (280/11-A, 280/11-B) were sent to our laboratory, and tissue samples were collected from lungs, spleens, livers, kidneys, and placentas for diagnostic investigations. Nucleic acids were purified using the DNeasy tissue kit (Qiagen) and QIAamp RNeasy minikit (Qiagen). Reverse transcription (RT)-PCR and PCR assays were performed using SuperScript one-step RT-PCR for long templates (Life Technologies) and LA PCR kit version 2.1 (TaKaRa Bio Inc.), respectively. Positive and negative controls were processed in parallel to the screened samples. The samples tested negative by PCR for Chlamydophila spp. 3, 8). Conversely, the pestivirus genome was detected with two different 24), and the virus was characterized as Hobi-like by a species-specific nested PCR (7) (Fig. 1A). Viral titers, quantified by a TaqMan-based real...

A Hobi-like pestivirus pair consisting of cytopathogenic (cp) and non-cytopathogenic (noncp) strains, Italy 83/10cp and Italy 83/10ncp, was isolated from the lung of a heifer that died of respiratory disease. The noncp and cp viruses were isolated on Madin-Darby bovine kidney cells and separated by plaque purification and end point dilution. Analysis of the nearly full-length genomes revealed that the two viruses were very closely related to each other and to the noncp Hobi-like strain Italy 1/10-1, which had been isolated a few weeks earlier from the same herd. One major difference between noncp and cp viruses concerned the presence of a cellular Jiv sequence in the 39 domain of the NS2-encoding region of the cp strain. This is the first study, to our knowledge, reporting the isolation and molecular characterization of a Hobi-like virus pair. INTRODUCTIONTogether with classical swine fever virus (CSFV), border disease virus (BDV) and other pestiviruses isolated from wild ruminants, bovine viral diarrhea virus (BVDV) belongs to the genus Pestivirus of the family Flaviviridae (Avalos- Ramirez et al., 2001;Becher et al., 2003;Simmonds et al., 2011). BVDV is an enveloped, single-stranded, positivesense RNA virus that is responsible for multiple clinical signs (Lindenbach et al., 2007) and there are two main species, termed BVDV-1 and BVDV-2 (Pellerin et al., 1994;Ridpath et al., 1994;Simmonds et al., 2011), with several subtypes within each species (Baule et al., 1997;Wolfmeyer et al., 1997;Becher et al., 1999; Vilcek et al., 1999a, b, c;Couvreur et al., 2002;Flores et al., 2002;Tajima, 2004). The BVDV genomic RNA, approximately 12.3 kb in size, encodes a polyprotein (NH 2 -N pro -C-E rns -E1-E2-p7-NS2-3-NS4A-NS4B-NS5A-NS5B-COOH) that is processed by viral and cellular proteases, thereby generating structural and non-structural proteins. The single large ORF is flanked by the 59 and 39 UTRs (Lindenbach et al., 2007).An atypical pestivirus, named D32/00_Hobi, was isolated from a contaminated batch of FCS originating from Brazil (Schirrmeier et al., 2004). Hobi-like pestiviruses contaminating FCS of South American origin were later detected in Switzerland (Stalder et al., 2005), Sweden (Liu et al., 2009a), Italy (Peletto et al., 2012), USA, Canada, Mexico and Australia (Xia et al., 2011). Strains responsible for natural infections were recovered in South America and Thailand from bubaline blood (Stalder et al., 2005) and bovine serum (Ståhl et al., 2007), but there was no evidence of associated clinical signs. All these viruses were proposed to belong to a new pestivirus species, tentatively termed BVDV-3 (Liu et al., 2009b). However, there is no agreement among pestivirologists about this proposal, considering the genetic and antigenic distance of the new viruses from other BVD viruses (J. Ridpath, personal communication). The first European Hobi-like virus strain Italy 1/10-1 was isolated from calves with severe respiratory disease in southern Italy (Decaro et al., 2011). This is also the first report, to our knowl...