Entomopathogenic fungi are the only insect pathogens able to infect their host by adhesion to the surface and penetration through the cuticle. Although the possibility of fungal infection per os was described almost a century ago, there is an information gap of several decades regarding this topic, which was poorly explored due to the continuous elucidation of cuticular infection processes that lead to insect death by mycosis. Recently, with the advent of next-generation sequencing technologies, the genomes of the main entomopathogenic fungi became available, and many fungal genes potentially useful for oral infection were described. Among the entomopathogenic Hypocreales that have been sequenced, Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Cordycipitaceae) is the main candidate to explore this pathway since it has a major number of shared genes with other non-fungal pathogens that infect orally, such as Bacillus thuringiensis Berliner (Bacillales: Bacillaceae). This finding gives B. bassiana a potential advantage over other entomopathogenic fungi: the possibility to infect through both routes, oral and cuticular. In this review, we explore all known entry gates for entomopathogenic fungi, with emphasis on the infection per os. We also set out the fungal infection process in a more integral approach, as a need to exploit its full potential for insect control, considering all of its virulence factors and the conditions needed to improve its virulence against insect that might offer some resistance to the common infection through the cuticle.

A total of 120 Burkholderia cepacia complex isolates collected during 2004 -2010 from 66 patients in two cystic fibrosis reference centers in Argentina were analyzed. Burkholderia contaminans was the species most frequently recovered (57.6%), followed by Burkholderia cenocepacia (15%), a species distribution not reported so far. The recA-PCR-based techniques applied to the B. contaminans isolates revealed that 85% of the population carried the recA-ST-71 allele. Our results showed the utility of BOX-PCR genotyping in analyzing B. contaminans diversity. This approach allowed us to address clonal transmission during an outbreak and the genetic changes occurring in infecting bacteria over the course of chronic infection. Burkholderia cepacia complex species are capable of causing chronic and often severe respiratory tract infections in cystic fibrosis (CF) patients and other types of infections in immunocompromised patients. Although many CF patients remain infected by these bacteria and yet stay relatively healthy for prolonged periods, others either have a severe decline in their pulmonary status or die shortly after the initial colonization (1). In Argentina, the first reports of B. cepacia complex bacteria infecting CF patients started around 1990. At that time, Burkholderia spp. were recovered sporadically and with a very low prevalence (Ͻ0.1%). The prevalence increased over the last decade from 0.2 to 3.6%, depending on the medical center. In early 2004, an outbreak involving main Argentine CF care centers occurred, and the proportion of patients from whom B. cepacia complex species were recovered ranged from 19 to 36% (2-4). Currently, through strict infection control procedures, the prevalence of Burkholderia spp. in local patients has decreased to approximately 10%. Recent worldwide surveillance studies concerning the distribution of B. cepacia complex species in CF patients have cited B. multivorans and B. cenocepacia as the most frequently recovered species. These species account for approximately 80% of the infected patients, and the prevalence of one or the other is geographically and temporally dependent (5-7). Unlike this worldwide situation, in Argentina a relatively high prevalence of B. contaminans followed by B. cenocepacia has been observed (3, 4). To our knowledge, no other geographical region has been reported in the literature to have such a high occurrence of B. contaminans infecting CF patients. In view of this particular scenario, coupled with the lack of biodiversity information available for B. contaminans species, we decided to study this local population by recA-PCR-based techniques and by repetitive element sequence-based PCR (rep-PCR) approaches. These methods allowed us to address the genetic diversity of B. contaminans isolates recovered during that outbreak along with the genetic changes occurring in the infecting bacteria over the course of a chronic infection.

As part of the innate humoral response to microbial attack, insects activate the expression of antimicrobial peptides (AMPs). Understanding the regulatory mechanisms of this response in the Chagas disease vector Triatoma infestans is important since biological control strategies against pyrethroid-resistant insect populations were recently addressed by using the entomopathogenic fungus Beauveria bassiana. By bioinformatics, gene expression, and silencing techniques in T. infestans nymphs, we achieved sequence and functional characterization of two variants of the limpet transcription factor (Tilimpet) and studied their role as regulators of the AMPs expression, particularly defensins, in fungus-infected insects.We found that Tilimpet variants may act differentially since they have divergent sequences and different relative expression ratios, suggesting that Tilimpet-2 could be the main regulator of the higher expressed defensins and Tilimpet-1 might play a complementary or more general role. Also, the six defensins (Tidef-1 to Tidef-6) exhibited different expression levels in fungus-infected nymphs, consistent with their phylogenetic clustering. This study aims to contribute to a better understanding of T. infestans immune response in which limpet is involved, after challenge by B. bassiana infection.