Genetic Diversity of Pilin From Kazakh Isolates of Moraxella bovoculi

Abstract

I nfectious bovine keratoconjunctivitis (IBK), is a highly contagious and infectious disease of the bovine eye characterized by conjunctivitis and ulcerative keratitis that occurs worldwide (Holzhauer and Visser, 2004;Kneipp, 2021). Infectious keratoconjunctivitis also occurs in other domestic (Motha et al., 2003) and wild (Giacometti et al., 2002) species and is generally considered to be a multifactorial disease. The most commonly isolated pathogen from IBK is Moraxella bovis (M. bovis) (McConnel et al., 2007). The presence of M. bovoculi isolates in most eye samples taken from IBK-affected cattle suggests a role for M. bovoculi in pathogenesis (Angelos, 2010). The frequency of co-isolation of these two species may indicate that M. bovoculi serves as an opportunistic agent in IBK (Loy and Brodersen, 2014). In a recent study using the PCR method, M. bovoculi was detected in 75% of the samples of the total number of samples examined (Zheng et al., 2019). Other data on a positive correlation between the clinical signs of IBK and the presence of M. bovoculi also indirectly support that this organism is involved in the pathogenesis of IBK (Loy and Brodersen, 2014;Schnee et al., 2015).Pilin is known to be one of the key pathogenic factors in M. bovis, as this protein allows moraxella to "stick" to research Article Abstract | Moraxella bovoculi (M. bovoculi) is commonly isolated from clinical cases of infectious bovine keratoconjunctivitis (IBK), however, the exact role of M. bovoculi in this disease remains unclear. Experimental Moraxella bovis (M. bovis) and M. bovoculi vaccines to prevent IBK based on recombinant pathogenic factors have been evaluated as alternatives to whole cell vaccines. Pilin is one candidate antigen for M. bovoculi, and is a key pathogenic factor necessary for attachment of M. bovis to the surface of the eye epithelium. To evaluate pilA diversity amongst Kazakh isolates of M. bovoculi, the pilA gene sequence was determined for 35 isolates of M. bovoculi. Ten genotypes (gNA1-gNA10) were identified which were 96.1% to 99.8% identical. It was found that as a result of the replacement of cytosine with thymine at the 97th position of the gNA8 genotype, a stop codon resulted which, if expressed, would have resulted in a truncated PilA. Phylogenetic analyses of the deduced amino acid sequences of PilA from isolates from Kazakhstan, in comparison with previously defined PilA groups in M. bovoculi, established that 68% of the Kazakh isolates belonged to group A, 8.6% to groups C and F. It was found that despite these isolates originating from geographically close regions, some of the studied isolates had unique amino acid sequences that were assigned to new M. bovoculi PilA groups designated K (2 isolates), L (2 isolates), and M (1 isolate).

Association of different microbes and pathogenic factors in cases of infectious bovine keratoconjunctivitis in cattle from Eastern Kazakhstan

“…Infectious bovine keratoconjunctivitis (IBK) is a contagious ocular disease of cattle characterized by ulcerative keratitis, corneal edema, and conjunctivitis. This disease is the most common eye condition of cattle [1] and occurs worldwide, including in Kazakhstan [2][3][4]. Although corneal ulcerations in cattle may heal with limited corneal scar formation, it is not uncommon for IBK to result in complete or partial loss of vision [5].…”