Neutralization against Omicron sublineages (BA.2/BA.5/BQ.1.1/XBB/XBB.1.5) in bivalent BNT162b2-vaccinated HCWs with or without risk factors, or following BT infection with Omicron.

SARS-CoV-2-BA.4/5-adapted-bivalent-BNT162b2-vaccine (bvBNT), developed in response to the recent emergence of immune-evasive Omicron-variants, has been given to individuals who completed at least 2-doses of the monovalent-BNT162b2-vaccine (mvBNT). In the present cohort study, we evaluated neutralization-titers (NT50s) against Wuhan-strain (SCoV2Wuhan) and Omicron-sublineages including BA.2/BA.5/BQ.1.1/XBB/XBB.1.5, and vaccine-elicited S1-binding-IgG in sera from participants-vaccinated with 5th-bvBNT following 4th-mvBNT. The 5th-bvBNT-dose elicited good protective-activity against SCoV2Wuhan with geometric-mean (gMean)-NT50 of 1966-2091, higher than the peak-values post-4th-mvBNT with no statistical significance, and favorable neutralization-activity against not only BA.5 but also BA.2, with ~ 3.2-/~ 2.2-fold greater gMean-NT50 compared to the peak-values post-4th-mvBNT-dose, in participants with or without risk factors. However, neutralization-activity of sera post-5th-bvBNT-dose was low against BQ.1.1/XBB/XBB.1.5. Interestingly, participants receiving bvBNT following breakthrough (BT) infection during Omicron-wave had significantly enhanced neutralization-activity against SCoV2Wuhan/BA.2/BA.5 with ~ 4.6-/~ 6.3-/~ 8.1-fold greater gMean-NT50, respectively, compared to uninfected participants receiving bvBNT. Sera from BT-infected-participants receiving bvBNT had enhanced neutralization-activity against BQ.1.1/XBB/XBB.1.5 by ~ 3.8-fold compared to those from the same participants post-4th-mvBNT-dose, and had enhanced gMean-NT50 ~ 5.4-fold greater compared to those of uninfected-participants' sera post-bvBNT. These results suggest that repeated stimulation brought about by exposure to BA.5's-Spike elicit favorable cross-neutralization-activity against various SARS-CoV-2-variants.

Neutralization activity of sera/IgG preparations from fully BNT162b2 vaccinated individuals against SARS-CoV-2 Alpha, Beta, Gamma, Delta, and Kappa variants.

In the present prospective study, 225 individuals in Kumamoto General Hospital, Japan, who received two-doses of BNT162b2 vaccine were enrolled/followed up over 150 days and neutralizing activity (NT50) of their sera and antiviral activity (EC50) of IgG purified from sera on day-60 post-1st-dose were determined against wild-type SARS-CoV-2 (SARS-CoV-2Wuhan) (n = 211) and 9 variants (Alpha, Beta, Gamma, Delta, and Kappa) (n = 45). Time-dependent changes of IgG-activity (n = 25) against SARS-CoV-2Wuhan and variants were also examined. Day-60 sera showed reduced NT50 by more than 50% against all variants examined, and greatest reduction was seen with Beta. IgG fractions of high-responders and moderate-responders showed similar fold-changes in EC50 against each variant compared to SARS-CoV-2Wuhan. Evaluation of EC50 of IgG obtained at different time-points (day-28 to -150) revealed time-dependent reduction of activity against all variants. However, against Delta, relatively long-lasting favorable antiviral activity (at least 150 days) was observed. Our data strongly suggest that the successful antecedent scale-up of mRNA-based vaccine administrations in Japan was the primary contributor to the lessening of the otherwise more devastating SARS-CoV-2 pandemic wave caused by the Delta variant. The present data that the effectiveness of vaccine against the then-dominant SARS-CoV-2 variant was likely associated with the moderation of the COVID-19 pandemic wave suggest that as in the case of influenza vaccines, the development of multivalent mRNA-based vaccines represent a generalizable approach to pre-emptively respond pandemic with mutable pathogens.

Development and validation of a cell-based assay system to assess human immunodeficiency virus type 1 integrase multimerization.

Multimerization of HIV-1 integrase (IN) subunits is required for the concerted integration of HIV-1 proviral DNA into the host genome. Thus, the disruption of IN multimerization represents a new avenue for intervening HIV-1 infection. Here, we generated a cell-based assay system to assess IN multimerization using a newly constructed bimolecular fluorescence complementation (BiFC-IN) system. BiFC-IN proteins were efficient in emitting fluorescence, and amino acid (AA) substitutions associated with IN multimerization attenuated fluorescence, suggesting that the BiFC-IN system may be useful for evaluating the profile of IN multimerization. A recently reported non-catalytic site IN inhibitor (NCINI), which allosterically induces IN over-multimerization/aggregation, significantly increased fluorescence in the BiFC-IN system. An IN's substitution, A128T, associated with viral resistance to NCINIs, decreased the NCINI-induced increase of fluorescence, suggesting that A128T reduces the potential for IN over-multimerization. Moreover, E11K and F181T substitutions known to inhibit IN tetramerization also reduced the NCINI-induced fluorescence increase, suggesting that NCINI-induced IN over-multimerization was more likely to occur from tetramer subunits than from dimer subunits. The present study demonstrates that our cell-based BiFC-IN system may be useful in elucidating the profile of IN multimerization, and also help evaluate and identify novel compounds that disrupt IN multimerization in living cells.