Respiratory Syncytial Virus Human Experimental Infection Model: Provenance, Production, and Sequence of Low-Passaged Memphis-37 Challenge Virus

Abstract

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children and is responsible for as many as 199,000 childhood deaths annually worldwide. To support the development of viral therapeutics and vaccines for RSV, a human adult experimental infection model has been established. In this report, we describe the provenance and sequence of RSV Memphis-37, the low-passage clinical isolate used for the model's reproducible, safe, experimental infections of healthy, adult volunteers. The predicted amino acid sequences for major proteins of Memphis-37 are compared to nine other RSV A and B amino acid sequences to examine sites of vaccine, therapeutic, and pathophysiologic interest. Human T- cell epitope sequences previously defined by in vitro studies were observed to be closely matched between Memphis-37 and the laboratory strain RSV A2. Memphis-37 sequences provide baseline data with which to assess: (i) virus heterogeneity that may be evident following virus infection/transmission, (ii) the efficacy of candidate RSV vaccines and therapeutics in the experimental infection model, and (iii) the potential emergence of escape mutants as a consequence of experimental drug treatments. Memphis-37 is a valuable tool for pre-clinical research, and to expedite the clinical development of vaccines, therapeutic immunomodulatory agents, and other antiviral drug strategies for the protection of vulnerable populations against RSV disease.

Deep sequencing of RSV from an adult challenge study and from naturally infected infants reveals heterogeneous diversification dynamics

“…Only a single amino acid residue (L protein position 176) was noted to have a minor population greater than 5% (82% N, 18% H). The observation of diversity at this site is consistent with previously published diversity described in a sister virus (Memphis-37c) sequenced by conventional Sanger methods (11) (Supplemental Figure 1). …”

“…Predicted CD4 and CD8 T cell epitopes were previously identified by Kim et al (11). Predicted B cell epitopes were identified and compiled from the literature (21–24).…”

“…Here, we expand these observations to normal human immune responses by analyzing longitudinal within-host data from two cohorts: (a) healthy immune-experienced adults experimentally infected with the same genetically well-characterized ultra-low-passaged RSV-A virus (11) and (b) infants hospitalized with severe manifestations of community-acquired RSV-A infection. These datasets allow us to ask how much diversity emerges over the course of infections in healthy adult hosts; how variable it is across hosts, when controlling for infection with the same virus; as well as how much diversity emerges in infants with severe manifestations of infection.…”

Delivery of ALX-0171 by inhalation greatly reduces respiratory syncytial virus disease in newborn lambs

“…Memphis 37 (M37) hRSV is a wild type RSV-A, first isolated from a 4 month-old infant 56 and used in human clinical studies 39 57-59 HEp-2 cells were infected in 300 cm 2 flasks at 0.5-1 multiplicity of infection (MOI) at a confluence of 80-90% by applying 4-5 mL of hRSV stock (Memphis 37 hRSV that was used originated from Meridian LifeScience, Memphis, TN, USA).…”

Controlled human infection with RSV: The opportunities of experimental challenge

“…The progenitor virus, RSV Memphis 37 (M37), was isolated from a child with bronchiolitis in 2006 [27]. RSV M37 was grown to high titre in Vero cell culture and individual lots tested extensively for the presence of adventitious agents.…”