Virulence and pathophysiology of the Congo Basin and West African strains of monkeypox virus in non-human primates

Abstract

Monkeypox virus is divided into Congo Basin and West African strains. The virulence and pathophysiology of two strains, Zr-599 (a Congo Basin monkeypox virus) and Liberia (a West African monkeypox virus), were evaluated in non-human primates. Four monkeys were infected by the subcutaneous (SC) and two by the intranasal (IN) inoculation routes for Zr-599 and Liberia at a dose of 10 6 p.f.u. One monkey in the Liberia/SC group was demonstrated to be co-infected with Gram-positive cocci and was excluded from analyses. Infections in three of the four Zr-599/ SC monkeys and in one of the three Liberia/SC monkeys were fatal. Virus genome levels in blood in the Zr-599/SC monkeys were approximately 10 times higher than those in the Liberia/SC monkeys. Zr-599 affected respiratory, genito-urinary and gastrointestinal tract organs more severely than Liberia. Zr-599 was more virulent than Liberia and one of the factors might be the difference in organ tropism.

A Single Vaccination of Nonhuman Primates with Highly Attenuated Smallpox Vaccine, LC16m8, Provides Long-term Protection against Monkeypox

“…The error bars shown in the line graph represent the standard deviations of the mean values. The graphs for the naïve-group monkeys (A) are exactly the same as those reported in a previous study (17).…”

“…The results of the pathological examinations in the naïve monkey group have been reported in a previous study (12,17). MPX-associated lesions were detected in most of the organs, including skin, such as in the lymphoid to vaccinia virus antigens (Fig.…”

“…Virus, smallpox vaccine, and cells: MPXV strain Zr-599, a highly virulent strain, was used in the challenge experiments (12,17). The infectious doses of MPXV were determined via plaque assays, using Vero cells obtained from American Type Cultures SUMMARY: Monkeypox virus (MPXV) causes human monkeypox (human MPX), which is a similar disease to smallpox in humans.…”

“…Scoring system for determining the severity of MPX: To compare the level of MPX severity, we used the scoring system developed in a previous study (17).…”

“…Laboratory data and cytokine responses: Total peripheral blood cell counts and serum biochemical tests, including tests for aspartate transaminase, alanine transaminase, lactate dehydrogenase, and C-reactive protein (CRP), were performed (17). The concentrations of tumor necrosis factor alpha (TNF-), gamma interferon (IFN-), and IL-6 in the serum samples were determined using a Human Cytokine 24-plex Antibody Bead Kit (BioSource Invitrogen, Camarillo, CA), according to the manufacturer's instructions.…”