Despite the impact of bovine group A rotaviruses (GARVs) as economically important and zoonotic pathogens, there is a scarcity of data on cross-species pathogenicity and extra-intestinal spread of bovine reassortant GARVs. During the course of characterizing the genotypes of all 11 genomic segments of bovine GARVs isolated from diarrheic calves in South Korea, a unique G6P[7] reassortant GARV strain (KJ9-1) was isolated. The strain harbors five bovine-like gene segments (VP7: G6; VP6: I2; VP1: R2; VP3: M2; NSP2: N2, and NSP4: E2), five porcine-like gene segments (VP4: P[7]; NSP1: A1; NSP3: T1, and NSP5: H1), and one human-like gene segment (VP2: C2). To investigate if this reassortant strain possessed cross-species pathogenicity in calves and piglets, and could induce viremia and extra-intestinal spread in calves, colostrum-deprived calves and piglets were experimentally inoculated with the KJ9-1 strain. The KJ9-1 strain caused severe diarrhea in experimentally infected calves with extensive intestinal villous atrophy, but replicated without causing clinical symptoms in experimentally infected piglets. By SYBR Green real-time RT-PCR, viral RNA was detected in sera of the calves at post-inoculation day (PID) 1, reaching a peak at PID3, and then rapidly decreasing from PID4. In addition, viral RNA was detected in the mesenteric lymph node, lungs, liver, choroid plexus, and cerebrospinal fluid. An immunofluorescence assay confirmed viral replication in the extra-intestinal organs and tissues of virus-inoculated calves. The data indicates that the homologous/heterologous origin of the NSP4 gene segment (E2 genotype), may play a key role in the ability to cause diarrhea in calves and piglets.
Highly pathogenic avian influenza (H5N1) among wild birds emerged simultaneously with outbreaks in domestic poultry in South Korea during November 2010–May 2011. Phylogenetic analysis showed that these viruses belonged to clade 2.3.2, as did viruses found in Mongolia, the People’s Republic of China, and Russia in 2009 and 2010.
We characterized low pathogenic avian influenza (LPAI) viruses of the H7 subtype that were isolated from domestic ducks and wild birds in South Korea from 2008 to 2011. A total of 20 H7 viruses were collected from live-bird markets (LBMs), duck farms and wild-bird habitats using avian influenza (AI) surveillance and epidemiological approaches. A phylogenetic analysis of the H7 viruses that were isolated from domestic ducks and wild birds demonstrated that they were separated into 12 genotypes (A-D and Wb-1-8, respectively), indicating genetic diversity. These H7 viruses were related to the recently isolated Eurasian LPAI H7 viruses and various influenza viruses that are circulating in Asia, including southern China and South Korea. The same genotype was not found between domestic poultry and wild-bird isolates; however, most of the H7 viruses in poultry (genotypes B and C) were closely related to the H7 virus isolated from a wild bird (genotype Wb-3). Animal-challenge studies revealed that certain H7 AI viruses replicated well only in chickens or ducks depending on the genotype, indicating that the pathogenicity of H7 viruses has the potential to be altered due to multiple reassortments, and these viruses can potentially expand their host range. Our results are evidence of abundant and frequent reassortment between H7 viruses in poultry and wild birds and emphasize the continuing need to monitor the evolutionary genetics of the influenza virus in poultry and wild birds.
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