To investigate the prevalence of subtypes A and C, and the existence of recombinants of both subtypes in the southeast of the Democratic Republic of Congo (DRC), blood samples were collected from 27 HIV-infected individuals in Likasi, located in an area bordering close to Zambia, and analyzed phylogenetically. Out of the 24 strains with a positive PCR profile for pol-IN and env-C2V3, 15 (62.5%) had a discordant subtype or CRF designation: one subtype A/G (pol/env), four A/U (unclassified), three G/A, one G/CRF01, three H/A, one J/C, one CRF02 (G)/A, and one U/A. Nine (37.5%) strains had a concordant subtype or CRF designation: five subtype A, two C, one D, and one CRF02/G. The remaining three samples negative for PCR with env-C2V3 primers used in this study were further analyzed with env-gp41 primers and revealed the presence of two profiles: two J/J (pol-IN/env-gp41) and one C/G. These data highlight the presence of a high proportion (16/27, 59.3%) of recombinant strains and a low prevalence (4.1 and 7.4%) of subtype C based on env-C2V3 and pol-IN analyses, respectively, in Likasi. In addition, this is the first report that CRF02_AG exists in DRC, though the epidemiological significance of the existence of CRF02_AG in DRC remains unknown.

In a previous study, we described the diverse growth capabilities of circulating seasonal influenza A viruses (IAVs) with low to high viral copy numbers in vitro. In this study, we analyzed the cause of differences in growth capability by evaluating pro-inflammatory cytokines (TNF-α, IL-6, IFN-β) and antiviral interferon-stimulated genes (ISG-15, IFIM1, and TRIM22). A549 cells (3.0 × 10⁵ cells) were inoculated with circulating seasonal IAV strains and incubated for 6 and 24 h. In cells inoculated for 6 h, IAV production was assessed using IAV-RNA copies in the culture supernatant and cell pellets to evaluate gene expression. At 24 h post-infection, cells were collected for IFN-β and ISG-15 protein expression. A549 cells inoculated with seasonal IAV strains with a high growth capability expressed lower levels of IFN-β and ISGs than strains with low growth capabilities. Moreover, suppression of the JAK/STAT pathway enhanced the viral copies of seasonal IAV strains with a low growth capability. Our results suggest that the expression of ISG-15, IFIM1, and TRIM22 in seasonal IAV-inoculated A549 cells could influence the regulation of viral replication, indicating the existence of strains with high and low growth capability. Our results may contribute to the development of new and effective therapeutic strategies to reduce the risk of severe influenza infections.

The correlation of viral growth capability (n = 156) with the viral load in nasopharyngeal swabs (n = 76) was assessed. Epidemic influenza A/H1N1, A/H3N2, and B viruses showed a wide range of growth capability (10⁴–10¹¹ copies/mL) in Madin-Darby canine kidney cells. The growth was correlated with the nasopharyngeal viral load (r = 0.53). Six selected strains showed growth-dependent cell death (r = 0.96) in a growth kinetics assay. Epidemic influenza viruses exhibit a wide range of growth capability. Growth capability should be considered one of the key factors in disease prognosis.

Extrahepatic viral infections are often accompanied by acute hepatitis, as evidenced by elevated serum liver enzymes and intrasinusoidal infiltration of CD8+ T cells, without direct infection of the liver. An example is infectious mononucleosis caused by primary infection with EBV. Previously, we demonstrated that airway infection of mice with murine γ-herpesvirus 68 (MHV68), a murine model of EBV, caused liver inflammation with elevated serum liver enzymes and intrahepatic infiltration of IFN-γ–producing CD8+ T cells and NK cells. Mechanistically, the expression of the CXCR3-ligand chemokines, which are commonly induced by IFN-γ and attract IFN-γ–producing Th1-type cells via CXCR3, was upregulated in the liver. Importantly, the liver inflammation was suppressed by oral neomycin, an intestine-impermeable aminoglycoside, suggesting an involvement of some products from the intestinal microbiota. In this study, we showed that the liver inflammation and the expression of the CXCR3-ligand chemokines in the liver were effectively ameliorated by i.p. administration of anti-TLR4 mAb or C34, a TLR4 blocker, as well as in TLR4-deficient mice. Conversely, intrarectal inoculation of Escherichia coli as an extraintestinal source of LPS aggravated liver inflammation in MHV68-infected mice with increased expression of the CXCR3-ligand chemokines in the liver. In contrast, the lung inflammation in MHV68-infected mice was not affected by oral neomycin, i.p. administration of C34, or TLR4 deficiency. Collectively, the LPS–TLR4 pathway plays a pivotal role in the liver inflammation of MHV68-infected mice at least in part by upregulating the CXCR3-ligand chemokines in the liver.

It has been considered that reduced susceptibility to antiretroviral drugs is influenced by drug adherence, drug tolerance and drug-resistance-related mutations in the HIV genome. In the present study, we assessed the intrinsic high viral growth capability as a potential viral factor that may influence their susceptibility to antiretroviral drugs using an in vitro model. Phytohemagglutinin-activated peripheral blood mononuclear cells (1.5 × 10⁶ cells) were infected with HIV isolates (10⁶ copies/mL). The culture was carried out at different concentrations (0.001–20 μM) of 13 synthetic antiretroviral compounds (six nucleoside/nucleotide reverse transcriptase inhibitors, one non-nucleoside reverse transcriptase inhibitor, four integrase inhibitors, and two protease inhibitors), and HIV production was assessed using HIV-RNA copies in culture. The 90% inhibitory concentration (IC₉₀) and pharmacokinetics of an antiretroviral agent were used as parameters to determine the reduced antiretroviral drug susceptibility of HIV isolates with high growth capability to synthetic antiretroviral compounds. The high growth capability of HIV isolates without any known drug resistance-related mutation affected their susceptibility to tenofovir (IC₉₀ = 2.05 ± 0.40 μM), lamivudine (IC₉₀ = 6.83 ± 3.96 μM), emtricitabine (IC₉₀ = 0.68 ± 0.37 μM), and efavirenz (IC₉₀ = 3.65 ± 0.77 μM). These antiretroviral drugs showed IC₉₀ values close to or above the maximum plasma concentration against HIV isolates with high growth capability without any known drug resistance-related mutation. Our results may contribute to the development of effective strategies to tailor and individualize antiretroviral therapy in patients harboring HIV isolates with high growth capability.