Mokola virus involved in a human contact (South Africa)

Abstract

Isolations of Mokola virus (MOKV) are rare, but in South Africa and Zimbabwe this genotype 3 lyssavirus variant has been occasionally found in domestic mammals (cats and a dog) with a total of 17 virus isolates (South Africa 10, Zimbabwe 7) having been recovered during the past 30 years. We report the identification of a MOKV isolate involved in a human contact in Grahamstown (Eastern Cape, South Africa) and a genetic comparison with previously characterized isolates. This reported MOKV case was in a previously immunized cat. While the continual recovery of MOKV isolates in domestic cats is speculative of the existence of a reservoir host species among bats or rodents, the lack of protection with currently used vaccines is discussed and the need for biologicals with a wider spectrum of protection against this lyssavirus variant is highlighted.

Diversity and Epidemiology of Mokola Virus

“…Generally, the genetic variance was shown to be inversely related to the spatial distribution of isolates. For example, South African MOKV isolates were shown to be closely related, but distinguishable based on province and as a cluster more distant from those made in a neighboring country, Zimbabwe [21], [33], [34]. Such patterns of genetic diversity may indicate extended periods of isolated evolution, as have been reported for terrestrial rabies virus variants [35].…”

“…In 1997 and 1998 three more isolations were made from rabies-vaccinated cats in KZN [18], [19]. Following several years in which MOKV was not encountered, two isolations were from rabies-vaccinated domestic cats in 2006 and 2008 from the EC province and these are the most recent known isolations of this virus [20], [21]. From South Africa all isolations of MOKV were from a domestic cat.…”

“…However, no rabies vaccine provided complete protection against MOKV [27], [28], [29], [30], [31], [32]. More evidence that RABV derived vaccines do not protect against MOKV infection is shown by circumstantial evidence of the fatal infections of numerous domestic animals that had been vaccinated against RABV [13], [18], [19], [20], [21]. Given this scenario and the apparent obscurity of MOKV, we argue that much more information is needed to improve our scant understanding of the epidemiology, disease dynamics and the ecology of this virus.…”

“…Some phylogenetic studies have been undertaken on MOKV [18], [20], [21], [33], [34], but these studies were invariably performed on a smaller number of isolates and limited to partial gene sequences. Despite these limitations, these studies provided some evidence of the existence of different virus clusters, delineated according to geographical incidence.…”

Lyssavirus Vaccine with a Chimeric Glycoprotein Protects across Phylogroups

“…The possibility of further terrestrial adaptation and consequent increased risk to humans is of concern. MOKV, a divergent member of phylogroup II, was one of the first non-RABV lyssaviruses to be discovered ( Shope et al., 1970 ), and lack of protection from RABV-based vaccines in animals has been well documented: for example, MOKV has been isolated from rabies-vaccinated domestic cats multiple times ( Nel et al., 2000 ; Sabeta et al., 2010 , 2007 ; von Teichman et al., 1998 ). Although rare cross-reactivity between RABV and MOKV has been observed, the current RABV vaccine is unlikely to provide protection against MOKV ( De Benedictis et al., 2016 ; Hanlon et al., 2005 ).…”