High-Purity Preparation of HSV-2 Vaccine Candidate ACAM529 Is Immunogenic and Efficacious In Vivo

Abstract

Genital herpes is a sexually transmitted infection (STI) caused by herpes simplex virus 2 (HSV-2) and to a lesser extent herpes simplex virus 1 (HSV-1). Infection by HSV-2 is life-long and is associated with significant cost to healthcare systems and social stigma despite the highly prevalent nature of the disease. For instance, the proportion of HSV-2 seropositive to seronegative adults is approximately 1 in 5 in the US and greater than 4 in 5 in some areas of sub-Saharan Africa. The replication-defective vaccine strain virus dl5-29 was re-derived using cells appropriate for GMP manufacturing and renamed ACAM529. Immunization with dl5-29 was previously reported to be protective both in mice and in guinea pigs, however these studies were performed with vaccine that was purified using methods that cannot be scaled for manufacturing of clinical material. Here we describe methods which serve as a major step towards preparation of ACAM529 which may be suitable for testing in humans. ACAM529 can be harvested from infected cell culture of the trans-complementing cell line AV529 clone 19 (AV529-19) without mechanical cell disruption. ACAM529 may then be purified with respect to host cell DNA and proteins by a novel purification scheme, which includes a combination of endonuclease treatment, depth filtration, anion-exchange chromatography and ultrafiltration/diafiltration (UF/DF). The resultant virus retains infectivity and is ∼ 200-fold more pure with respect to host cell DNA and proteins than is ACAM529 purified by ultracentrifugation. Additionally, we describe a side-by-side comparison of chromatography-purified ACAM529 with sucrose cushion-purified ACAM529, which shows that both preparations are equally immunogenic and protective when tested in vivo.

Immune Evasion by Herpes Simplex Viruses

“…A somewhat similar result was found in another study with an 0ΔNLS-attenuated HSV strain, which elicits antibodies against numerous virus-infected cell proteins (ICP) and gB, within others ( Table 6) [234][235][236]. Other attenuated HSV strains have also provided promising results in numerous mouse models and should move onto clinical trials, such as the HSV-2 dl5-29 strain, which has U L 5 and U L 29 deleted from its genome ( Table 6) [237][238][239]. Additional attenuated viral strains that confer significant protection against viral challenge are HSV strains that are impaired at infecting neurons, such as a gD mutant virus [240], HSV deleted at U L 39 (ICP10ΔPK) [241], and HSV deleted at gE ( Table 6) [242].…”

Improving immunogenicity and efficacy of vaccines for genital herpes containing herpes simplex virus glycoprotein D

“…These strategies should be evaluated in tandem or in combination with other formulations, including attenuated live virus vaccines to determine which approach will prevent genital herpes infection in naïve subjects and reduce symptomatic disease and genital HSV shedding in previously infected individuals [118,119].…”

“…Recombinant subunit vaccines containing gD2 antigen are the topic of this review; however, other candidate vaccines are also being considered, including an attenuated live virus vaccine [119,120]. The current attenuated live virus vaccines that are licensed for use include measles, mumps, rubella, polio, rotavirus, yellow fever and varicella.…”

Evasión de la respuesta inmune por virus herpes simplex

“…Es importante destacar que algunas de estas cepas atenuadas, como aquella que carece del gen ICP0,confieren en el modelo animal mayores protecciones contra VHS-2 que la formulación vacuna basada en gD probada en humanos 164 . Cepas virales que carecen de genes involucrados en la replicación viral (UL5 y UL29) 165,166 o en los procesos de entrada y diseminación del virus (gE) 167 también han sido evaluadas en modelos animales y demostrado ser seguras, inmunogénicas e inducir inmunidad protectora contra la patología por VHS. Actualmente, estudiamos una cepa atenuada de VHS-2 que carece de la glicoproteína gD, la que induce protección contra VHS-2 genital en el modelo murino datos no publicados).…”