Study of Camelpox Virus Pathogenesis in Athymic Nude Mice

Abstract

Camelpox virus (CMLV) is the closest known orthopoxvirus genetically related to variola virus. So far, CMLV was restricted to camelids but, recently, three human cases of camelpox have been described in India, highlighting the need to pursue research on its pathogenesis, which has been hampered by the lack of small animal models. Here, we confirm that NMRI immunocompetent mice are resistant to intranasal (i.n.) CMLV infection. However, we demonstrate that CMLV induced a severe disease following i.n. challenge of athymic nude mice, which was accompanied with a failure in gaining weight, leading to euthanasia of the animals. On the other hand, intracutaneous (i.c.) infection resulted in disease development without impacting the body weight evolution. CMLV replication in tissues and body fluids was confirmed in the two models. We further analyzed innate immune and B cell responses induced in the spleen and draining lymph nodes after exposure to CMLV. In both models, strong increases in CD11b+F4/80+ macrophages were seen in the spleen, while neutrophils, NK and B cell responses varied between the routes of infection. In the lymph nodes, the magnitude of CD11c+CD8α+ lymphoid and CD11c+CD11b+ myeloid dendritic cell responses increased in i.n. challenged animals. Analysis of cytokine profiles revealed significant increases of interleukin (IL)-6 and IL-18 in the sera of infected animals, while those of other cytokines were similar to uninfected controls. The efficacy of two antivirals (cidofovir or HPMPC, and its 2, 6-diaminopurine analog) was evaluated in both models. HPMPC was the most effective molecule affording 100% protection from morbidity. It appeared that both treatments did not affect immune cell responses or cytokine expression. In conclusion, we demonstrated that immunodeficient mice are permissive for CMLV propagation. These results provide a basis for studying the pathogenesis of CMLV, as well as for evaluating potential antiviral therapies in an immunodeficiency context.

Emergence of Cowpox: Study of the Virulence of Clinical Strains and Evaluation of Antivirals

“…Human embryonic lung fibroblasts (HEL) were used as described in [17]. Five CPXV strains were selected ( Table 1 ), three of them, i.e.…”

Mutations Conferring Resistance to Viral DNA Polymerase Inhibitors in Camelpox Virus Give Different Drug-Susceptibility Profiles in Vaccinia Virus

“…In order to extend our comprehension of how specific mutations in the DNA polymerase of different OPVs affect the susceptibility to ANPs, we studied the impact of homologous mutations within E9L of CMLV and VACV. After the selection of CMLV resistant to (S)-HPMPDAP, a potent anti-CMLV molecule in vitro and in vivo (26,27), amino acid residues within the viral DNA polymerase of CMLV were identified as the cause of resistance to (S)-HPMPDAP. Recombinant CMLV and VACV were constructed by transfection of plasmids containing the desired mutation, and a detailed comparison of their drug-susceptibility profiles to viral DNA polymerase inhibitors was performed.…”

KAY-2-41, a Novel Nucleoside Analogue Inhibitor of OrthopoxvirusesIn VitroandIn Vivo

“…To determine the extent of viral replication, five mice in the VACV-WR-infected groups that received no treatment or that received KAY-2-41 at 50 mg/kg were euthanized at day 5 postinfection (p.i. ), and serum as well as lungs, liver, spleen, kidneys, and mesenteric lymph nodes were collected and processed as previously described (41). Briefly, after tissue disruption and homogenization, samples were used for virus titer and viral load determinations.…”

“…The virus titers in lung, liver, spleen, and kidney tissue homogenates were determined on HEL cells. Real-time quantitative PCR (qPCR) was used to quantify viral DNA, as previously reported (41). Organs from one mouse of each group were used for histological examination (41).…”