No abstract

To standardize human herpesvirus 8 (HHV-8) antibody assays for application to asymptomatic infection, a blinded comparison was done of seven immunofluorescence assays and ELISAs. Five experienced laboratories tested a serum panel from 143 subjects in 4 diagnostic groups. Except for a minor capsid protein ELISA, the other six tests detected HHV-8 antibodies most frequently in classic (80%-100%) and AIDS-related (67%-91%) Kaposi's sarcoma, followed by human immunodeficiency virus-seropositive patients (27%-60%), and least frequently in healthy blood donors (0-29%). However, these six assays frequently disagreed on individual sera, particularly for blood donor samples. Current HHV-8 antibody tests have uncertain accuracy in asymptomatic HHV-8 infection and may require correlation with viral protein or nucleic acid detection. Antibody assays are useful for epidemiologic investigations, but the absolute prevalence of HHV-8 infection in the United States cannot yet be determined.

Kaposi's sarcoma (KS)-associated herpesvirus or human herpesvirus 8 (KSHV/HHV8) is the likely cause of KS and primary effusion lymphomas or body cavity-based lymphomas (BCBLs). A latency-associated nuclear immunofluorescence antigen (LANA) (D. H.

Neutralizing antibodies targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) block severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into cells via surface-expressed angiotensin-converting enzyme 2 (ACE2). We used a surrogate virus neutralization test (sVNT) and SARS-CoV-2 S protein-pseudotyped vesicular stomatitis virus (VSV) vector-based neutralization assay (pVNT) to assess the degree to which serum antibodies from coronavirus disease 2019 (COVID-19) convalescent patients interfere with the binding of SARS-CoV-2 S to ACE2. Both tests revealed neutralizing anti-SARS-CoV-2 S antibodies in the sera of ~90% of mildly and 100% of severely affected COVID-19 convalescent patients. Importantly, sVNT and pVNT results correlated strongly with each other and to the levels of anti-SARS-CoV-2 S1 IgG and IgA antibodies. Moreover, levels of neutralizing antibodies correlated with the duration and severity of clinical symptoms but not with patient age. Compared to pVNT, sVNT is less sophisticated and does not require any biosafety labs. Since this assay is also much faster and cheaper, sVNT will not only be important for evaluating the prevalence of neutralizing antibodies in a population but also for identifying promising plasma donors for successful passive antibody therapy.