Viraemic frequencies and seroprevalence of non-primate hepacivirus and equine pegiviruses in horses and other mammalian species.

Non-primate hepacivirus (NPHV), equine pegivirus (EPgV) and Theiler's disease associated virus (TDAV) are newly discovered members of two genera in the Flaviviridae family, Hepacivirus and Pegivirus respectively, that include human hepatitis C virus (HCV) and human pegivirus (HPgV). To investigate their epidemiology, persistence and clinical features of infection, large cohorts of horses and other mammalian species were screened for NPHV, EPgV and TDAV viraemia and for past exposure through serological assays for NPHV and EPgV-specific antibodies. NPHV antibodies were detected in 43% of 328 horses screened for antibodies to NS3 and core antibodies, of which three were viraemic by PCR. All five horses that were stablemates of a viraemic horse were seropositive, as was a dog on the same farm. With this single exception, all other species were negative for NPHV antibodies and viraemia: donkeys (n=100), dogs (n=112), cats (n=131), non-human primates (n=164) and humans (n=362). EPgV antibodies to NS3 were detected in 66.5% of horses, including 10 of the 12 horses that had EPgV viraemia. All donkey samples were negative for EPgV antibody and RNA. All horse and donkey samples were negative for TDAV RNA. By comparing viraemia frequencies in horses with and without liver disease, no evidence was obtained that supported an association between active NPHV and EPgV infections with hepatopathy. The study demonstrates that NPHV and EPgV infections are widespread and enzootic in the study horse population and confirms that NPHV and potentially EPgV have higher frequencies of viral clearance than HCV and HPgV infections in humans.

The non-primate hepacivirus 5' untranslated region possesses internal ribosomal entry site activity.

The 5' untranslated region (5'UTR) of the recently described non-primate hepacivirus (NPHV) contains a region with sequence homology to the internal ribosomal entry site (IRES) of hepatitis C virus (HCV) and GB virus B (GBV-B). Here, we demonstrated internal translation initiation by the NPHV 5'UTR in a bicistronic vector. An RNA stem-loop upstream of the NPHV IRES was structurally distinct from corresponding regions in HCV and GBV-B, and was not required for IRES function. Insertion of the NPHV stem-loop into the corresponding region of the HCV 5'UTR within the HCV subgenomic replicon significantly impaired RNA replication, indicating that long-range interactions between the 5'UTR and cis-acting downstream elements within the NPHV genome are not interchangeable with those of HCV. Despite similarities in IRES structure and function between hepaciviruses, replication elements in the NPHV 5'UTR appear functionally distinct from those of HCV.

Hepatitis C virus infections in the Democratic Republic of Congo exhibit a cohort effect.

The prevalence and genetic diversity of hepatitis C virus (HCV) and human pegivirus (HPgV) in many regions of sub-Saharan Africa is poorly characterized, including in the Democratic Republic of Congo--the largest country in the region and one of the most populous. To address this situation we conducted a molecular epidemiological survey of HCV and HPgV (previously named GB Virus C or hepatitis G virus) in samples collected in 2007 from 299 males from the DRC, whose ages ranged from 21 to 71 years old. Samples were tested for the presence of HCV antibodies by ELISA and reactive samples were subsequently tested for HCV RNA using RT-PCR in which both the HCV Core and NS5B genome regions were amplified. Remaining samples were tested for HPgV RNA and the HPgV NS3 genome region of positive samples was amplified. For HCV, 13.7% of the samples were seropositive (41/299) but only 3.7% were viremic (11/299). HPgV RNA was found in 12.7% (33/259) of samples. HCV viremia was strongly associated with age; the percentage of samples that contained detectable HCV RNA was ~0.5% in those younger than 50 and 13% in those older than 50. Our study represents the first systematic survey of HCV genetic diversity in the DRC. HCV sequences obtained belonged to diverse lineages of genotype 4, including subtypes 4c, 4 k, 4 l and 4r, plus one unclassified lineage that may constitute a new subtype. These data suggest that HCV in the DRC exhibits an age 'cohort effect', as has been recently reported in neighbouring countries, and are consistent with the hypothesis that HCV transmission rates were higher in the mid-twentieth century, possibly as a result of parenteral, iatrogenic, or other unidentified factors. Different HCV subtypes were associated with individuals of different ages, implying that HCV infection in the DRC may have arisen through multiple separate HCV epidemics with different causes.

Nonprimate hepaciviruses in domestic horses, United kingdom.

Although the origin of hepatitis C virus infections in humans remains undetermined, a close homolog of this virus, termed canine hepacivirus (CHV) and found in respiratory secretions of dogs, provides evidence for a wider distribution of hepaciviruses in mammals. We determined frequencies of active infection among dogs and other mammals in the United Kingdom. Samples from dogs (46 respiratory, 99 plasma, 45 autopsy samples) were CHV negative by PCR. Screening of 362 samples from cats, horses, donkeys, rodents, and pigs identified 3 (2%) positive samples from 142 horses. These samples were genetically divergent from CHV and nonprimate hepaciviruses that horses were infected with during 2012 in New York state, USA. Investigation of infected horses demonstrated nonprimate hepacivirus persistence, high viral loads in plasma (10(5)-10(7) RNA copies/mL), and liver function test results usually within reference ranges, although several values ranged from high normal to mildly elevated. Disease associations and host range of nonprimate hepaciviruses warrant further investigation.

Species association of hepatitis B virus (HBV) in non-human apes; evidence for recombination between gorilla and chimpanzee variants.

Hepatitis B virus (HBV) infections are widely distributed in humans, infecting approximately one third of the world's population. HBV variants have also been detected and genetically characterised from Old World apes; Gorilla gorilla (gorilla), Pan troglodytes (chimpanzee), Pongo pygmaeus (orang-utan), Nomascus nastusus and Hylobates pileatus (gibbons) and from the New World monkey, Lagothrix lagotricha (woolly monkey). To investigate species-specificity and potential for cross species transmission of HBV between sympatric species of apes (such as gorillas and chimpanzees in Central Africa) or between humans and chimpanzees or gorillas, variants of HBV infecting captive wild-born non-human primates were genetically characterised. 9 of 62 chimpanzees (11.3%) and two from 11 gorillas (18%) were HBV-infected (15% combined frequency), while other Old world monkey species were negative. Complete genome sequences were obtained from six of the infected chimpanzee and both gorillas; those from P. t .ellioti grouped with previously characterised variants from this subspecies. However, variants recovered from P. t. troglodytes HBV variants also grouped within this clade, indicative of transmission between sub-species, forming a paraphyletic clade. The two gorilla viruses were phylogenetically distinct from chimpanzee and human variants although one showed evidence for a recombination event with a P.t.e.-derived HBV variant in the partial X and core gene region. Both of these observations provide evidence for circulation of HBV between different species and sub-species of non-human primates, a conclusion that differs from the hypothesis if of strict host specificity of HBV genotypes.