HoBi-like viruses

Abstract

The genus Pestivirus is composed of 4 important pathogens of livestock: Bovine viral diarrhea virus 1 and 2 (BVDV-1 and BVDV-2), Classical swine fever virus (CSFV), and Border disease virus of sheep (BDV). BVDV are major pathogens of cattle, and infection results in significant economic loss worldwide. A new putative pestivirus species, tentatively called “HoBi-like,” “BVDV-3,” or “atypical pestiviruses,” was first identified in Europe in fetal bovine serum (FBS) imported from Brazil. HoBi-like viruses are related to BVDV at the genetic and antigenic levels. Further, the disease caused by these new viruses resembles clinical presentations historically associated with BVDV infection, including growth retardation, reduced milk production, respiratory disease, reduced reproductive performance, and increased mortality among young stock. Current BVDV diagnostic tests may fail to detect HoBi-like viruses or to differentiate between BVDV and HoBi-like viruses. Further, commercial tests for BVDV exposure, based on serological response, do not reliably detect HoBi-like virus exposure, and cross protection against HoBi-like viruses conferred by current BVDV vaccines is likely limited. As many HoBi-like viruses, characterized to date, were isolated from FBS originating from Brazil, it is assumed that the agent is probably widespread in Brazilian herds. Nevertheless, reports of natural infection in Southeast Asia and Europe demonstrate that these viruses are not restricted to South America. Increased demand for FBS has led to widespread distribution of FBS originating in HoBi-like virus endemic regions. The contamination of such FBS with HoBi-like viruses may lead to spread of this virus to other regions.

Clinical and virological characteristics of calves experimentally infected with a Brazilian isolate of bovine viral diarrhea virus type 1a

“…Nevertheless, it is possible that the virus load isolated from nasal discharge samples on day 1 pi was a residue after the inoculation. BVDV infection can cause immunosuppression subsequent to viral replication in mononuclear cells; the latter also facilitates the occurrence of secondary respiratory and enteric infections (POTGIETER, 1995;BAUERMANN et al, 2013;FALkENBERG et al, 2014). In this study, WBCs decreased in all infected animals after day 3 pi, the largest reduction being observed on day 9 pi (20-37%), and cell counts almost returned to normal by day 15 pi.…”

“…Previous reports showed that exposure to BVDV may cause a subclinical infection or several clinical manifestations in cattle (BOTTON et al, 1998;BIANCHI et al, 2011). Previously, experimental inoculation of calves with field isolates has been used as a method to examine infection parameters under controlled conditions (BRUM et al, 2002;DECARO et al, 2012;BAUERMANN et al, 2013;RIDPATH et al, 2013); such analyses enable the characterization of many aspects of infection, such as its acute phase and pathogenesis, host immune response, the transmission between animals, and the efficacy of vaccine protection and diagnostic testing (BRUM et al, 2002;BAUERMANN et al, 2013). Several studies have been conducted using this protocol and the results of these studies showed that virulence is highly variable among strains (BRUM et al, 2002;DECARO et al, 2012;RIDPATH et al, 2013).…”

“…It can induce immunosuppression and allows the establishment of secondary infections in the respiratory and enteric systems (POTGIETER, 1995;RIDPATH, 2010). BVDV is classified under the Pestivirus genus of the Flaviviridae family, has a singlestranded, 12.5-kb positive sense RNA genome, and contains an enveloped icosahedral capsid of 40-60nm in diameter (HORZINEk, 1991 (BAUERMANN et al, 2013).…”

Generation of Calves Persistently Infected with HoBi-Like Pestivirus and Comparison of Methods for Detection of These Persistent Infections

“…In contrast, HoBi-like viruses do not appear to be endemic on all continents. In South America, HoBi-like virus has been associated with reproductive disorders in Brazilian cattle herds and with the death of water buffalos (3,4,15). In Italy, the infection of cattle with HoBi-like virus resulted in abortion, respiratory disease, death of young animals, and the birth of PI calves (5,6,16).…”

“…Infection with a putative pestivirus species, variously referred to as HoBi-like virus, BVDV3, and atypical pestivirus, leads to a repertoire of syndromes indistinguishable from that of BVD. Clinical signs include upper respiratory disease, fever, transient immune suppression, death among young stock, reproductive losses, and the generation of persistently infected (PI) animals (3)(4)(5)(6)(7)(8).…”