Resiniferatoxin promotes adult worm expulsion in Trichinella spiralis-infected rats by Th2 immune response modulation.

BACKGROUND: The immune response during T spiralis infection is characterized by an increase in eosinophils and mast cells, as well as Th2 cytokine production, such as interleukin (IL)-4, IL-10 and IL-13, promoting T spiralis expulsion from the host. However, this response damages the host, favouring the parasite survival. In the search for new pharmacological strategies that protect against T spiralis infection, a recent study showed that treatment with resiniferatoxin (RTX) modulates the Th1 cytokines production, reducing muscle parasite burden. OBJECTIVE: To evaluate the effect of RTX treatment on the Th2 cytokines production, the number of eosinophils, mast cells and the intestinal expulsion of T spiralis. METHODS: Serum levels of IL-4, IL-10 and IL-13 were quantified by ELISA; the number of eosinophils, mast cells and the adult worms of T spiralis in the small intestine was quantified. RESULTS: RTX treatment increased serum levels of IL-4, IL-10 and IL-13, and it decreases intestinal eosinophilia, however, favours the mastocytosis, promoting T spiralis intestinal expulsion. CONCLUSIONS: These findings suggest that RTX is capable to modulate the Th2 immune response, promoting T spiralis expulsion, which contributes to the defence against T spiralis infection, placing the RTX as a potential immunomodulatory drug.

Role of esxG and esxH Genes in Drug-Resistant Mycobacterium.

Tuberculosis drug resistance (DR) is a global problem that is not fully elucidated. Previously, overexpression of esxG and esxH genes was reported in a multidrug-resistant (MDR) Mycobacterium tuberculosis isolate compared with a reference H37Rv strain. To evaluate the roles of esxG and esxH in DR, analysis of their regulatory and coding sequences in sensitive and resistant strains was performed, and the expression levels of their transcriptional regulators IdeR, Zur, and MntR were evaluated. esxG and esxH were expressed heterologously using mycobacterial constructs, and the orthologs Msmeg_0620 and Msmeg_0621 were attenuated in Mycobacterium smegmatis by antisense knockdown. We found no differences in the regulatory and coding sequences of esxG and esxH between the sensitive strain and the MDR isolate. Expression analysis of transcriptional regulators showed that ideR was upregulated in isoniazid (INH)-resistant isolates; in addition, growth inhibition of the M. smegmatis strain was observed in the presence of rifampicin (RIF) and INH when esxG and esxH were expressed heterologously, while faster growth in the presence of RIF was observed when the orthologs were attenuated. In conclusion, the expression of esxG and esxH altered the growth of Mycobacterium in the presence of INH and RIF, suggesting a potential association with DR.

Prevalence of Rotavirus Genogroup A and Norovirus Genogroup II in Bassaseachic Falls National Park Surface Waters in Chihuahua, Mexico.

In areas lacking potable water treatment, drinking contaminated water may represent a public health threat. In addition to enteropathogenic bacteria and parasites, fecal contamination in water environments is associated with the transmission of enteric viruses and other causal agents of infectious disease. Rotavirus and norovirus are the main enteric viral agents responsible for diarrheic outbreaks. The aim of the present study was to detect seasonal variation of rotavirus and norovirus in the surface water at Bassaseachic Falls National Park during 2013. Rivers and streams within and nearby this park were sampled once in each season during 2013. Viral concentration was carried out by a handmade filtration equipment, using a commercial electropositive membrane coupled with the virus absortion elution technique (VIRADEL©). Detection of rotavirus and norovirus was performed by SYBR Green reverse transcription-real time polymerase chain reaction (SYBR GREEN© RT-qPCR) analyses. Norovirus genogroup II was detected in samples collected in June and October 2013. In the case of rotavirus, genogroup A was detected in March and June. The presence of rotavirus and norovirus was related to viral acute diarrhea in children less than five years of age, who were inhabiting the sampled areas. This may indicates that the contaminated water was potentially a risk factor for regional diarrheic outbreaks.

Therapeutic Effects of Resiniferatoxin Related with Immunological Responses for Intestinal Inflammation in Trichinellosis.

The immune response against Trichinella spiralis at the intestinal level depends on the CD4+ T cells, which can both suppress or promote the inflammatory response through the synthesis of diverse cytokines. During the intestinal phase, the immune response is mixed (Th1/Th2) with the initial predominance of the Th1 response and the subsequent domination of Th2 response, which favor the development of intestinal pathology. In this context, the glucocorticoids (GC) are the pharmacotherapy for the intestinal inflammatory response in trichinellosis. However, its therapeutic use is limited, since studies have shown that treatment with GC suppresses the host immune system, favoring T. spiralis infection. In the search for novel pharmacological strategies that inhibit the Th1 immune response (proinflammatory) and assist the host against T. spiralis infection, recent studies showed that resiniferatoxin (RTX) had anti-inflammatory activity, which decreased the serum levels of IL-12, INF-γ, IL-1ß, TNF-α, NO, and PGE2, as well the number of eosinophils in the blood, associated with decreased intestinal pathology and muscle parasite burden. These researches demonstrate that RTX is capable to inhibit the production of Th1 cytokines, contributing to the defense against T. spiralis infection, which places it as a new potential drug modulator of the immune response.

Gonotrophic cycle and survivorship of Culex quinquefasciatus (Diptera: Culicidae) using sticky ovitraps in Monterrey, northeastern Mexico.

Mark-release-recapture experiments were conducted to determine the length of the gonotrophic cycle and rate of survivorship of Culex quinquefasciatus Say in Monterrey, northeastern Mexico. A total of 2,352 field-caught Cx. quinquefasciatus females were marked and released at 8-12 h postemergence in 2 field trials. Sticky ovitraps were used to recapture marked gravid females. One hundred and ten (4.6%) marked females were recaptured during a 12-day sampling period. Recapture rates for the 2 individual trials were 6.4% and 3.5%. The length of the gonotrophic cycle, calculated as the average time between the initial blood meal and the time of recapture of gravid females, was 2-3 days. The first blood-fed mosquitoes were recaptured on the 2nd day postrelease. Gravid egg-laying females were most commonly recaptured at 2-3 days postfeeding. Daily survival estimates for the 2 release dates were of 0.871 and 0.883, respectively.

Host-feeding preference of Culex quinquefasciatus in Monterrey, northeastern Mexico.

Studies were conducted to determine the host selection patterns of Culex quinquefasciatus in the municipalities of Guadalupe and Escobedo near Monterrey, northeastern Mexico. Mosquitoes were captured inside and outside houses. Chickens and humans were the most common blood sources for all Cx. quinquefasciatus females, accounting for nearby 70% of blood meals. Human blood was detected by enzyme-linked immunosorbent assay in 36.4% and 28.4% of engorged females resting inside houses in Guadalupe and Escobedo, respectively. The proportions of indoor resting females fed on chicken blood were 38.7% and 56.7%, respectively. The weighted and unweighted human blood index (HBI) values were calculated, by using indoor and outdoor data, from the proportions of humanfed mosquitoes. Weighted means (HBI) estimates for Guadalupe and Escobedo were 23.0% and 15.4%, respectively. The forage ratios (FRs) for humans were <1.0 (with or without chicken populations); consequently, it seems that these mosquitoes feed on humans with less frequency in comparison with chickens, horses, and pigs. The FRs for chickens were the highest of all available hosts (1.7 and 3.2), and they were the most abundant hosts in Escobedo, and the second most abundant in Guadalupe, indicating a selective bias of Cx. quinquefasciatus for chickens (i.e. ornithophagic).