Discovery of a human parvovirus B19 analog (Erythroparvovirus) in catsLanave, Pellegrini, Diakoudi
et alSci Rep (2025) 15 (1), 9650
Abstract: Two feral cats (from the same colony) were presented to the veterinary clinic for weakness, weight loss, and anorexia. The cats were part of a study on feline hepatotropic viruses (collection A, 43 animals). On metaviromic investigation, parvoviral reads were identified in the sera of the two cats. The feline parvovirus genome was 5.3 kb long with an organization similar to other members of the Erythroparvovirus genus. In the ORF1 (nonstructural proteins) and ORF2 (VP1/VP2 precursor) the feline virus displayed 43.1% and 49.1% nucleotide identity to human parvovirus B19, and 48.9% and 56.6% to chipmunk parvovirus. Sequence identity to canine/feline protoparvovirus (Protoparvovirus carnivoran 1) was as low as 36.5% % and 29.2% in the ORF1 and ORF2, respectively. Using a quantitative PCR assay, the virus was also identified in an additional ten cats (prevalence 27.6%, 12/43) from collection A and in 15/1150 (1.3%) of archival sera (collection B), revealing a higher infection rate in cats with altered hepatic markers, suggestive of hepatic distress. The findings of our study extend the list of known parvoviruses in the feline host.© 2025. The Author(s).
Evaluation of hepatitis A virus recombinant proteins for detecting anti-HAV IgM and IgG antibodiesHunderkar, Ganorkar, Walimbe
et alMicrobiol Spectr (2025)
Abstract: Hepatitis A virus (HAV) is a major causative agent of self-limiting liver infections. India was highly endemic for HAV in the past; children were exposed to the virus at an early age without any disease symptoms and developed lifelong immunity. With improvements in living conditions, an epidemiological transition is occurring. There is a significant increase in hepatitis A outbreaks involving adolescents and young adults. The gold standard for hepatitis A diagnosis is anti-HAV IgM antibodies. Although antibody responses are primarily targeted against HAV structural proteins (capsid proteins), non-structural proteins are also immunogenic. In the present study, we expressed HAV capsid proteins VP1-2A, VP0 (VP4 + VP2), VP3, and non-structural protein 3CPro in the bacterial system and explored the possible use of these as antigens to detect anti-HAV IgM and IgG antibodies using a well-defined serum sample panel. The capsid protein-based assays showed overall less sensitivity for detection of both anti-HAV IgM and IgG antibodies as compared to whole virus antigen-based commercial assays. Among capsid proteins, rVP1-2A showed the highest sensitivity (86.3%) and specificity (84.2%) in detecting anti-HAV IgG, while rVP0 (VP2 + VP4) exhibited the highest sensitivity (79.5%) and specificity (80.2%) for IgM antibodies. Interestingly, r3CPro exhibited higher sensitivity (96.9%) and specificity (93.2%) in IgM detection and 93.94% sensitivity and 88% specificity for IgG, indicating its usefulness in detecting both anti-HAV IgM and IgG antibodies during the acute phase of the disease. Though 3CPro appeared to be useful in differentiating antibody responses due to infection and vaccination, our analysis revealed that the anti-3CPro antibody response is short-lived after natural infection, and hence, it cannot be used as a marker to differentiate between infection and vaccination. However, 3CPro would be useful for developing a hepatitis A diagnostic assay.Hepatitis A was highly endemic in India earlier. With recent developments, there is a shift in the endemicity to intermediate levels. This has resulted in the occurrence of hepatitis outbreaks with symptomatic infections in adolescents and adults. Occasionally, the disease manifestations are serious, leading to acute liver failure. In such a situation, there is a need for a timely diagnosis of the infection.
The CRAC channel inhibitor BTP2 restricts Tulane virus and human norovirus replication independent of store-operated calcium entryScribano, Gebert, Engevik
et albioRxiv (2025)
Abstract: Human norovirus is the leading cause of viral gastroenteritis across all age groups. While there is a need for human norovirus antivirals, therapeutic development has been hindered by a lack of cell culture systems and animal models of infection. Surrogate viruses, such as Tulane virus (TV), have provided tractable systems to screen potential antiviral compounds. Our previous work demonstrated that Tulane virus encodes a viral ion channel, which dysregulates cytosolic calcium signaling. We set out to investigate whether host pathways triggered by viral ion channel activity, including store-operated calcium entry (SOCE), play a role in virus replication. Using pharmacologic inhibitors and genetically engineered cell lines, we establish that the SOCE inhibitor, BTP2, reduces TV replication in an SOCE-independent manner. We observed a significant reduction in TV replication, protein expression, and RNA synthesis in cells with both pre- and post-infection BTP2 treatment. By serial passage and plaque isolation, we demonstrate that TV quasi-species have mixed susceptibility and resistance to BTP2. Sequence comparison of the quasi-species revealed that amino acid changes in the structural proteins were associated with drug resistance. We utilized reverse genetics to generate TV with the resistance-associated VP1 and VP2 amino acid changes and found that a single amino acid change in VP1 (I380M) conferred BTP2 resistance. Further, expression of resistant VP2 alone was sufficient to partially rescue the replication of susceptible virus. Together, this supports that TV structural proteins are the targets of BTP2. Finally, using human intestinal organoids, we demonstrate that BTP2 significantly reduces human norovirus replication.Our work identifies BTP2 as a potential human norovirus antiviral pharmacophore and highlights the utility of targeting calicivirus structural proteins to restrict viral replication. Further, we establish a system whereby Tulane virus can be used to screen novel antiviral candidates and establish their mechanism of action. Together, this will facilitate rapid preclinical validation of other novel human norovirus therapeutics.
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